MCQs AND EMQs IN HUMAN PHYSIOLOGY pdf - غير معروف

MCQs and EMQs in

HUMAN

PHYSIOLOGY

edition

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MCQs and EMQs in

HUMAN
PHYSIOLOGY

Ian C Roddie

CBE, DSc, MD, FRCPI

Emeritus Professor of Physiology, The Queen's University of Belfast; former
Head of Medical Education, National Guard King Khalid Hospital, Jeddah,
Saudi Arabia

William FM Wallace

BSc, MD, FRCP, FRCA, FCARCSI, FRCSEd

Emeritus Professor of Applied Physiology, The Queen’s University of Belfast;
former Consultant in Physiology, Belfast City Hospital, Belfast, N. Ireland

A member of the Hodder Headline Group

LONDON

edition

with answers and
explanatory comments

First published in Great Britain in 1971
Second edition 1977
Third edition 1984
Fourth edition 1994
Fifth edition 1997
This sixth edition published in 2004 by
Arnold, a member of the Hodder Headline Group,
338 Euston Road, London NW1 3BH
http://www.arnoldpublishers.com

Distributed in the United States of America by
Oxford University Press Inc.,
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Whilst the advice and information in this book are believed to be true and
accurate at the date of going to press, neither the author[s] nor the publisher
can accept any legal responsibility or liability for any errors or omissions
that may be made. In particular (but without limiting the generality of the
preceding disclaimer) every effort has been made to check drug dosages;
however it is still possible that errors have been missed. Furthermore,
dosage schedules are constantly being revised and new side-effects
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recommended in this book.

British Library Cataloguing in Publication Data
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ISBN 0 340 811919

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Preface

How to use the book

2 CardiovascuIar system

5 Neuromuscular system

9 Reproductive system

l0. General questions

11 Sport and exercise physiology

12 Interpretative questions

CONTENTS

This book has now reached its sixth edition since it was first published over 30 years ago. Our
aim to base the questions on generally accepted aspects of physiology most relevant to clini-
cal practice seems to have been fulfilled – medical, dental and other health care students and
doctors in specialty training in countries around the world have told us of the book’s relevance
and usefulness.

We have tried to cover most of the concepts and knowledge typically asked for in physiol-

ogy examinations and to concentrate on the core knowledge that is essential to pass them. We
believe that students who score consistently well in these questions know enough to face most
examinations in physiology with confidence. By concentrating on the area where yes/no
answers can be given to questions with reasonable certainty, we have had to exclude areas
where knowledge is as yet conjectural and speculative. We have tried to avoid excessive detail
in the way of facts and figures; those which are included are of value in medical practice. Both
conventional and SI units are generally quoted. Comments on the answers are given on the
reverse of each question. We hope that, with the comments, the book will provide a compact
revision tutor, encouraging understanding rather than rote learning.

For most questions the common five-branch MCQ format has been used. The stem and a

single branch constitute a statement to be judged True or False by the reader. Care has been
taken that the statements in any question are not mutually exclusive, so five independent deci-
sions are required to answer each question. This system has the advantage of simplicity and
brevity over most other forms of multiple-choice question. In this edition, a further opportu-
nity has been taken to prune and edit questions for greater compactness, clarity and precision
and to bring in new areas of knowledge which have emerged since the last edition went to
press. We have also tended to expand the comments in an effort to increase the clarity of our
explanations and so add to the educational value of the self-assessment exercise.

The book is divided into sections, each section containing questions related to one of the

main physiological systems of the body. They cover both basic and applied aspects of the sub-
ject. The applied questions are designed so that the answers may be deduced mainly by making
use of basic physiological knowledge and should provide a link with clinical practice. There is
also a section on sports and exercise physiology and one containing ‘Interpretative’ questions
to provide practice in the interpretation of data, diagrams and figures. A new feature in this
edition is the addition of a number of Extended Matching Questions (EMQs) for each section of
the book. EMQs are an alternative form of multiple-choice question where answers have to be
selected from lists of options. They are becoming increasingly popular in undergraduate and
postgraduate examinations.

We thank colleagues for suggesting questions and all who commented on previous editions.

We continue to welcome such comments.

ICR

WFMW

September 2003

PREFACE

1. A stimulus to fill gaps in your knowledge

This book is intended as a revision tutor and should help you to revise your physiology in prep-
aration for examinations. It is particularly aimed at helping you to identify areas where your
knowledge and understanding need to be improved. The statements in this book are presented
so that you can commit yourself in written opinion and can then confirm correct information
and identify errors. The comments should reinforce your knowledge when you are correct and
indicate why you were mistaken if your answer is wrong.

2. Scoring your answers – multiple choice questions

Answer, say, 20 questions (100 decisions), aiming to complete them in about 50 minutes.
In our experience of this type of question (one point tested in each Part), it is best for can-
didates to answer virtually all questions.

Score your answers by giving

⫹1 for a correct response, ⫺1 for an incorrect response and

0 for any omitted. It is suggested that this approach is in line with professional life when
many true/false decisions must be taken – send the patient to hospital? Begin a certain
treatment? Carry out surgery urgently? The penalties for a wrong decision can be consid-
erable!

As a very approximate guide, the following scale would apply to candidates who have not
spent time memorizing particular questions:

50–60

fair

60–70

good

70–90

excellent

90–100

outstanding

3. Scoring your answers – extended matching questions

For these questions it is usual not to subtract marks for wrong answers, since the chance of
randomly getting the correct answer is much less than for multiple-choice questions, where it
is 50%. The same stratification of results (above) can then be applied.

4. Range of options

Please note for the MCQs that all, some, or none of the branches in each question may be true.
Also, for the EMQs a given option may be used more than once, or not at all.

HOW TO USE THIS BOOK

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MCQs

Questions 1–7

1. Extracellular fluid in adults differs from intracellular fluid in that its

Volume is greater.

Tonicity is lower.

Anions are mainly inorganic.

Sodium:potassium molar ratio is higher.

pH is lower.

2. Blood group antigens (agglutinogens) are

Carried on the haemoglobin molecule.

Beta globulins.

Equally immunogenic.

Not present in fetal blood.

Inherited as recessive Mendelian characteristics.

3. Total body water, expressed as a percentage of body weight

Can be measured with an indicator dilution technique using deuterium oxide.

Is smaller on average in women than in men.

Rises following injection of posterior pituitary extracts.

Falls during starvation.

Is less than 80 per cent in young adults.

4. Breakdown of erythrocytes in the body

Occurs when they are 6–8 weeks old.

Takes place in the reticulo-endothelial system.

Yields iron, most of which is excreted in the urine.

Yields bilirubin which is carried by plasma protein to the liver.

Is required for the synthesis of bile salts.

5. A person with group A blood

Has anti-B antibody in the plasma.

May have the genotype AB.

May have a parent with group O blood.

May have children with group A or group O blood only.

Whose partner is also A can only have children of groups A or O.

6. Blood platelets assist in arresting bleeding by

Releasing factors promoting blood clotting.

Adhering together to form plugs when exposed to collagen.

Liberating high concentrations of calcium.

Releasing factors causing vasoconstriction.

Inhibiting ﬁbrinolysis by blocking the conversion of plasminogen to plasmin.

7. Plasma bilirubin

Is a steroid pigment.

Is converted to biliverdin in the liver.

Does not normally cross cerebral capillary walls.

Is freely ﬁltered in the renal glomerulus.

Is sensitive to light.

MCQ

BODY FLUIDS

Body fluids – answers

Answers

False

Cells contain half to two-thirds of the total body fluid.

False

It is the same; if it were lower, osmosis would draw water into the cells.

True

Mainly Cl

⫺

and HCO

⫺

; inside, the main anions are protein and organic phos-

phates.

True

Around 30:1; the intracellular ratio is about 1:10.

False

Intracellular pH is lower due to cellular metabolism.

False

They are part of the red cell membrane.

False

They are glycoproteins.

False

A, B and D antigens are more immunogenic than the others.

False

Fetal blood may elicit immune responses if it enters the maternal circulation.

False

They are Mendelian dominants.

True

O (heavy water) exchanges with water in all body fluid compartments.

True

Women carry relatively more fat than men and fat has a low water content.

True

ADH in the extracts inhibits water excretion by the kidneys.

False

It rises as fat stores are metabolized to provide energy.

True

70 per cent, the percentage in the lean body mass, is about the maximum per cent
possible.

False

The normal erythrocyte lifespan is 16–18 weeks.

True

The RES removes effete RBCs from the circulation.

False

Most of the iron is retained for further use.

True

The protein makes the bilirubin relatively water-soluble.

False

Bile salts are synthesized from sterols in the liver.

True

This appears about the time of birth.

False

This would make them blood group AB.

True

They could inherit an A gene from the other parent to give genotype AO.

False

B or AB are possible depending on the partner’s genes.

True

In this case, neither parent has the B gene.

True

e.g. Thromboplastin, part of the intrinsic pathway.

True

Vascular leaks are sealed by such platelet plugs.

False

High Ca

⫹

levels are not needed for haemostasis; normal levels are adequate.

True

e.g. Serotonin (5-hydroxytryptamine).

False

Serotonin from platelets can release vascular plasminogen activators.

False

It is a porphyrin pigment derived from haem.

False

Bilirubin is derived from biliverdin formed from haem, not the other way about.

True

The ‘blood–brain barrier’ normally prevents bilirubin entering brain tissue.

False

The bilirubin–protein complex is too large to pass the glomerular ﬁlter.

True

Light converts bilirubin to lumirubin which is excreted more rapidly; photo-
therapy may be used in the treatment of haemolytic jaundice in children.

MCQ

Body fluids – questions

Questions 8–13

8. Monocytes

Originate from precursor cells in lymph nodes.

Can increase in number when their parent cells are stimulated by factors released from
activated lymphocytes.

Unlike granulocytes, do not migrate across capillary walls.

Can transform into large multinucleated cells in certain chronic infections.

Manufacture immunoglobulin M.

9. Erythrocytes

Are responsible for the major part of blood viscosity.

Contain the enzyme carbonic anhydrase.

Metabolize glucose to produce CO

and H

Swell to bursting point when suspended in 0.9 per cent (150 mmol/litre) saline.

Have rigid walls.

10. Human plasma albumin

Contributes more to plasma colloid osmotic pressure than globulin.

Filters freely at the renal glomerulus.

Is negatively charged at the normal pH of blood.

Carries carbon dioxide in blood.

Lacks the essential amino acids.

11. Neutrophil granulocytes

Are the most common leukocyte in normal blood.

Contain proteolytic enzymes.

Have a lifespan in the circulation of 3–4 weeks.

Contain actin and myosin microﬁlaments.

Are present in high concentration in pus.

12. Bleeding from a small cut in the skin

Is normally diminished by local vascular spasm.

Ceases within about ﬁve minutes in normal people.

Is prolonged in severe factor VIII (antihaemophilic globulin) deﬁciency.

Is greater from warm skin than from cold skin.

Is reduced if the affected limb is elevated.

13. Antibodies

Are protein molecules.

Are absent from the blood in early fetal life.

Are produced at a greater rate after a ﬁrst, than after a second, exposure to an antigen
six weeks later.

Circulating as free immunoglobulins are produced by B lymphocytes.

With a 1 in 8 titre are more concentrated than ones with a 1 in 4 titre.

MCQ

Body fluids – answers

Answers

False

They originate from stem cells in bone marrow.

True

Activated T cells release GMCSF (granulocyte/macrophage colony stimulating
factor) which stimulates monocyte stem cells to proliferate.

False

After 4–6 days in the circulation, monocytes migrate out to become tissue macro-
phages.

True

The ‘giant cells’ seen in tissues affected by tuberculosis and leprosy.

False

Immunoglobulins are made by ribosomes in lymphocytes.

True

Blood viscosity rises exponentially with the haematocrit.

True

It catalyses the reaction CO

⫹H

⫽H

⫹

⫹HCO

⫺

True

Glycolysis generates the energy needed to maintain electrochemical gradients
across their membranes.

False

This is isotonic with their contents.

False

The walls deform easily to squeeze through capillaries.

10.

True

Its greater mass and lower molecular weight provide more osmotically active par-
ticles.

False

Only a small amount is ﬁltered normally and this is reabsorbed by the tubules.

True

Blood pH is well above albumin’s isoelectric point so negative charges (COO

⫺

)

predominate.

True

As carbamino protein (R-NH

⫹CO

⫽R-NH COOH).

False

It is a ﬁrst class protein containing essential and non-essential amino acids.

11.

True

They comprise 60–70 per cent of circulating leukocytes.

True

Their granules contain such enzymes, which, with toxic oxygen metabolites, can
kill and digest the bacteria they engulf.

False

Less than a day.

True

Responsible for their amoeboid motility.

True

Pus consists largely of dead neutrophils.

12.

True

Due to the effects of tissue damage and serotonin on vascular smooth muscle.

True

This is the upper limit of the normal ‘bleeding time’.

False

Factor VIII increases clotting time, not bleeding time.

True

Warmth dilates skin blood vessels.

True

Intravascular pressure is reduced in an elevated limb.

13.

True

They are made by ribosomes in plasma cells.

True

Immunological tolerance prevents the fetus forming antibodies to its own pro-
teins.

False

The response to the second exposure is greater since the immune system has been
sensitized by the ﬁrst exposure.

True

T lymphocytes are responsible for cell-mediated immunity.

True

Antibody with a 1 in 8 titre is detected at greater dilution than one with a 1 in 4
titre.

MCQ

Body fluids – questions

Questions 14–19

14. Circulating red blood cells

Are about 1 per cent nucleated.

May show an intracellular network pattern if appropriately stained.

Are distributed evenly across the blood stream in large blood vessels.

Travel at slower velocity in venules than in capillaries.

Deform as they pass through the capillaries.

15. Lymphocytes

Constitute 1–2 per cent of circulating white cells.

Are motile.

Can transform into plasma cells.

Decrease in number following removal of the adult thymus gland.

Decrease in number during immunosuppressive drug therapy.

16. The specific gravity (relative density) of

Red cells is less than that of plasma.

Plasma is due more to its protein than to its electrolyte content.

Plasma decreases as extracellular fluid and electrolytes are lost.

Blood is higher on average in women than in men.

Urine can fall below 1.000 in a water diuresis

17. Blood

Makes up about 7 per cent of body weight.

Forms a higher percentage of body weight in fat than in thin people.

Volume can be calculated by multiplying plasma volume by the haematocrit (expressed
as a percentage).

Volume rises after water is drunk.

Expresses serum when it clots.

18. The cell membranes in skeletal muscle

Are impermeable to fat-soluble substances.

Are more permeable to sodium than to potassium ions.

Become more permeable to glucose in the presence of insulin.

Become less permeable to potassium in the presence of insulin.

Show invaginations which connect to a system of intracellular tubules involved in exci-
tation contraction coupling.

19. The osmolality of

A solution determines its freezing point.

Intracellular fluid is about twice that of extracellular fluid.

1.8 per cent sodium chloride is about twice that of normal plasma.

5 per cent dextrose solution is about ﬁve times that of 0.9 per cent saline.

Plasma is due more to its protein than to its electrolyte content.

MCQ

Body fluids – answers

Answers

14.

False

Nucleated red cells are not normally seen in peripheral blood.

True

Reticulocytes, the most immature circulating RBCs, show this pattern when
stained with certain dyes.

False

They form an axial stream away from the vessel wall.

False

The capillary bed has a greater total cross-sectional area than the venular bed.

True

Normal cells, around 7 microns in diameter, become bullet-shaped as they pass
through 5 micron diameter capillaries.

15.

False

About 20 per cent of leukocytes are lymphocytes.

True

They migrate by amoeboid movement to areas of chronic inflammation.

True

As plasma cells they manufacture humoral antibodies.

False

The thymus is atrophied and has little function in the adult.

True

Lymphocytes and immune responses are closely linked.

16.

False

Red cells are heavier and hence sediment on standing.

True

The mass of plasma proteins (70–80 grams/litre) far exceeds that of plasma elec-
trolytes (about 10 grams/litre).

False

It increases; plasma speciﬁc gravity is an index of ECF volume if protein levels
are normal.

False

It is higher in men, who have a higher haematocrit.

False

The speciﬁc gravity of pure water is 1.000; urine is water plus solutes.

17.

True

For example, 5 kg (about 5 litres) in a 70 kg man.

False

Since fat tissue is relatively avascular, the reverse is true.

False

It can be calculated by multiplying plasma volume by 1/1 minus haematocrit
(expressed as a decimal).

True

The water is absorbed into the blood.

True

Serum is plasma minus its clotting factors.

18.

False

The membrane consists largely of lipid.

False

The reverse is true; sodium ions, being more hydrated than potassium ions, are
larger complexes.

True

Thus glucose is stored as muscle glycogen after a meal.

False

They become more permeable; injections of insulin and glucose lower the serum
potassium level.

True

These are called the T system of tubules.

19.

True

Depression of the freezing point is an index of a solution’s osmolality.

False

Their osmolality is the same; osmotic water movements ensure that this is so.

True

Plasma has the tonicity of a normal saline solution (0.9 per cent sodium chloride).

False

They have the same number of particles.

False

Proteins account for only 1 per cent of plasma osmolality.

MCQ

Body fluids – questions

Questions 20-25

20. The pH

Of arterial blood normally ranges from 7.2 to 7.6.

Units express [H

⫹

] in moles/litre.

Of blood is directly proportional to the P

Of blood is directly proportional to [HCO

⫺

Of urine is usually less than 7.

21. Cerebrospinal fluid

Is an ultraﬁltrate of plasma.

Is the main source of the brain’s nutrition.

Has the same pH as arterial blood.

Has a higher glucose concentration than has plasma.

Has a higher calcium concentration than has plasma.

22. Antigens

Are usually proteins or polypeptide molecules.

Can only be recognized by immune system cells previously exposed to that antigen.

Are normally absorbed from the gut via lymphatics and carried to mesenteric lymph
nodes.

Induce a smaller immune response when protein synthesis is suppressed.

Are taken up by antigen-presenting macrophages which activate the immune system.

23. Blood eosinophils

Have agranular cytoplasm.

Are about a quarter of all leukocytes.

Are relatively abundant in the mucosa of the respiratory, urinary and alimentary tracts.

Release cytokines.

Increase in number in viral infections.

24. Normal blood clotting requires

Inactivation of heparin.

Inactivation of plasmin (ﬁbrinolysin).

Calcium ions.

An adequate intake of vitamin K.

An adequate intake of vitamin C.

25. Antibodies (agglutinins) of the A and B red cell antigens (agglutinogens)

Are present in fetal plasma.

Cause haemolysis of RBCs containing the A and B antigens when added to a suspension
of red cells in saline.

Do not normally cross the placental barrier.

Have a molecular weight in excess of 500 000.

Are monovalent.

MCQ

Body fluids – answers

Answers

20.

False

The range is normally between 7.35 and 7.45.

False

They express it as the negative logarithm of the [H

⫹

] in moles/litre.

False

raises [H

⫹

] and hence lowers pH.

True

[HCO

⫺

] lowers [H

⫹

] by buffering and hence raises pH.

True

The normal diet leaves acidic, rather than alkaline, residues.

21.

False

It is secreted actively by the choroid plexuses.

False

Brain nutrition is delivered mainly by cerebral blood flow.

False

It is around 7.3 compared with 7.4 in blood.

False

It is about two-thirds that of plasma.

False

About half; protein-bound calcium is negligible in CSF.

22.

True

Large carbohydrate molecules may also be antigenic.

False

The ability to recognize foreign antigens is innate and does not depend on pre-
vious exposure to them.

False

Antigens, being proteins or carbohydrates, are not normally absorbed; they are
digested in the gut.

True

Antibodies are proteins synthesized by ribosomes in activated lymphocytes.

True

Antigens can also act directly on receptors on lymphocyte membranes.

23.

False

They have eosinophilic granules (eosinophilic granulocytes).

False

Only 1–4 per cent of white cells are eosinophils.

True

They are involved in mucosal immunity.

True

Interleukin 4 and platelet activating factor (PAF).

False

Their number increases in parasitic infections and allergic conditions.

24.

False

The anticoagulant effects of heparin are overwhelmed.

False

Blood clots in spite of the ﬁbrinolytic system.

True

Removal of calcium ions prevents clotting.

True

Vitamin K is needed by the liver for synthesis of prothrombin and other factors.

False

The spontaneous bleeding from the gums etc. seen in scurvy is due to capillary
abnormality, not a clotting defect.

25.

False

They form shortly after birth, possibly in response to A and B antigens carried
into the body by invading bacteria.

False

They cause agglutination (clumping) of A, B and AB cells.

True

Unlike Rh antibodies which have a smaller molecular size.

True

Around 1 000 000.

False

They are divalent and hence cause red cells to adhere to one another during
agglutination.

MCQ

Body fluids – questions

Questions 26-31

26. Lymph

Contains plasma proteins.

Vessels are involved in the absorption of amino acids from the intestine.

Production increases during muscular activity.

Does not normally contain cells.

Flow is aided by contraction of adjacent skeletal muscles.

27. Blood platelets

Are formed in the bone marrow.

Are normally more numerous than white cells.

Have a small single-lobed nucleus.

Increase in number after injury and surgery.

Alter shape when in contact with collagen.

28. The conversion of fibrinogen to fibrin

Is effected by prothrombin.

Involves the disruption of certain peptide linkages by a proteolytic enzyme.

Is followed by polymerization of ﬁbrin monomers.

Is inhibited by heparin.

Is reversed by plasmin (ﬁbrinolysin).

29. An appropriate dilution indicator for measuring

Total body water is sucrose.

Plasma volume is radioactive sodium.

Extracellular fluid volume is inulin.

Intracellular fluid volume directly is heavy water (deuterium oxide).

Total body potassium is radioactive potassium.

30. Thirst can be

Produced by a rise in plasma tonicity.

Produced by stimulation of certain areas in the hypothalamus.

Produced by a fall in blood volume.

Associated with decreased secretion of ADH.

Relieved by water intake before the water has been absorbed from the gut.

31. Intravenous infusion of

Two litres of normal saline restores blood volume in a patient who suddenly lost two
litres of blood.

Bicarbonate is appropriate for patients being treated for cardiac and respiratory arrest.

Potassium-free fluids are appropriate for a patient with severe vomiting.

Isotonic glucose will expand both intracellular and extracellular fluid compartments.

Hypertonic saline will raise intracellular osmolality.

MCQ

Body fluids – answers

Answers

26.

True

Derived from plasma proteins leaked from capillaries into the tissues; it returns
these to the blood.

False

Lymph vessels are involved in the uptake and transport of absorbed fat.

True

Increased capillary pressure due to muscle vasodilatation increases tissue fluid
formation.

False

It contains lymphocytes derived from lymph nodes.

True

In addition, intrinsic rhythmic contractions in lymphatics help to propel lymph.

27.

True

They are formed from megalokaryocytes.

True

By a factor of 20 or more.

False

No nucleus – but the cytoplasm contains electron dense granules, lysosomes and
mitochondria.

True

This increases the tendency of blood to clot.

True

They put out pseudopodia and adhere to the collagen and to one another.

28.

False

It is effected by thrombin; prothrombin is the inactive precursor of thrombin.

True

Thrombin breaks off the solubilizing end groups.

True

Polymerized ﬁbrin monomers form the strands of the clot meshwork.

True

This is a rapidly acting anticoagulant.

False

Plasmin does not convert ﬁbrin back to ﬁbrinogen, it degrades both ﬁbrin and
ﬁbrinogen to products which can inhibit thrombin.

29.

False

Sucrose does not cross the cell membrane freely to equilibrate with ICF.

False

Sodium ions migrate easily from plasma to equilibrate with interstitial fluid.

True

Inulin crosses capillary walls freely but does not enter cells.

False

ICF volume is not measured directly; it is calculated by measuring ECF volume
and total body water and subtracting the former from the latter.

True

Radioactive K

⫹

equilibrates with the body pool of non-radioactive K

⫹

; both iso-

topes are treated similarly in the body.

30.

True

Stimulation of osmoreceptors by the increased tonicity generates thirst sensation.

True

The supraoptic nucleus of the hypothalamus contains osmoreceptors.

True

This can happen, even though blood tonicity is unchanged; volume receptors
may be involved.

False

ADH secretion is increased.

True

Flushing out the mouth with water can provide temporary relief from thirst.

31.

False

Some of the saline escapes from the circulation to the interstitial fluid.

True

It corrects the acidosis caused by accumulation of lactic acid and CO

in the tis-

sues.

False

Alimentary secretions are rich in potassium.

True

Glucose is metabolized, leaving the water to be distributed in both compartments.

True

Hypertonic extracellular fluid will draw water osmotically from the cells.

MCQ

Body fluids – questions

Questions 32–37

32. Excessive tissue fluid (oedema) in the legs may

Be associated with a raised extracellular fluid volume.

Result from hepatic disease.

Result from blockage of pelvic lymphatics.

Increase local interstitial fluid pressure.

Result from a high arterial blood pressure in the absence of heart failure.

33. Haemolytic disease of the newborn

Affects mainly babies of Rh-positive mothers.

Occurs mainly in babies who lack D agglutinogen.

Causes jaundice which clears rapidly after birth.

Can be treated by transfusing the affected baby with Rh-positive blood.

Can be prevented by injecting the mother with anti-D agglutinins just after delivery.

34. The appearance of centrifuged blood may suggest that

Anaemia is present if there is more plasma than packed cells.

The plasma lipid level is high.

The patient has jaundice.

Haemolysis has occurred.

The patient has leukaemia.

35. Patients with moderate to severe anaemia have a reduced

Cardiac output.

Incidence of vascular bruits.

2:3-diphosphoglycerate blood level.

Arterial P

Capacity to raise oxygen consumption in exercise.

36. Iron deficiency

Frequently follows persistent loss of blood from the body.

Is more common in men than in women.

May cause anaemia by inhibiting the rate of multiplication of RBC stem cells.

May cause large pale erythrocytes to appear in peripheral blood.

Anaemia should normally be treated by injections of iron

37. Severe reactions are likely after transfusion of blood group

A to a group B person.

O to a group AB person.

A to a group O person.

A to a group AB person.

O Rh- negative to a group AB Rh-positive person.

MCQ

Body fluids – answers

Answers

32.

True

Oedema is an increase in the interstitial component of ECF.

True

Albumin deﬁciency reduces plasma colloid osmotic pressure.

True

Protein accumulates in interstitial fluid and reduces the colloid osmotic pressure
gradient across the capillary wall.

True

This contributes to a new pressure equilibrium.

False

Arteriolar constriction in hypertension raises arterial, but not capillary, pressure.

33.

False

It affects babies of Rh-negative mothers when the child’s red cell membranes
carry the D antigen.

False

It occurs in Rh-positive babies.

False

The jaundice deepens rapidly after birth as bilirubin is no longer excreted by the
maternal liver.

False

This would be attacked by maternal Rh antibodies in the infant’s blood; Rh-
negative blood is given.

True

These destroy fetal Rh-positive cells in the maternal circulation before such cells
can sensitize her to D antigen.

34.

False

If the normal percentage of plasma in centrifuged blood is about 55 per cent.

True

If the plasma is cloudy or even milky.

True

If the plasma is yellow.

True

If the plasma is red.

True

If the buffy coat is greatly thickened.

35.

False

Output rises to compensate for the blood’s reduced O

carrying capacity.

False

Bruits are common since increased flow velocity and decreased blood viscosity
increase the likelihood of turbulent flow.

False

2:3-DPG is increased, shifting the dissociation curve to the right so that blood
gives up its oxygen more easily.

False

Arterial P

is normal; it is O

content which is reduced.

True

Due to the reduced capacity to deliver O

to the muscles.

36.

True

Especially if dietary intake of iron is limited.

False

It is more common in women due to menstrual blood loss.

False

It causes anaemia by limiting the rate of haemoglobin synthesis.

False

In iron deﬁciency anaemia, RBCs are small and pale due to lack of haemoglobin.

False

Oral iron is avidly absorbed in iron deﬁciency states.

37.

True

The recipients have anti-A antibody.

False

Group O people are ‘universal donors’.

True

The recipients have anti-A antibody.

False

Group AB persons, ‘universal recipients’, lack anti-A and anti-B antibodies.

False

The recipients lack anti-A, anti-B and anti-Rh antibodies.

MCQ

Body fluids – questions

Questions 38–43

38. The haematocrit (packed cell volume)

May be obtained by centrifugation of blood.

May be calculated by multiplying the mean cell volume by the red cell count.

Rises in a patient who sustains widespread burns.

Rises following injections of aldosterone.

Rises in macrocytic megaloblastic anaemias such as pernicious (B

deﬁciency) anaemia.

39. Red cell formation is increased

By giving vitamin B

injections to healthy people on a normal diet.

In blood donors one week after a blood donation.

In patients with haemolytic anaemia.

By giving injections of erythropoietin to nephrectomized patients.

In patients who have a raised blood reticulocyte count.

40. Vitamin B

deficiency may

Result from disease of the terminal part of the ileum.

Result in anaemia with small RBCs well ﬁlled with haemoglobin.

Cause wasting (atrophy) of the gastric mucosa.

Cause a reduction in the circulating platelet level.

Cause pathological changes in the central nervous system.

41. A raised blood pH and bicarbonate level is consistent with

Metabolic acidosis.

Partly compensated respiratory alkalosis.

A reduced P

Chronic renal failure with a raised P

A history of persistent vomiting of gastric contents.

42. A patient with partly compensated respiratory acidosis

Must have a raised P

May have a reduced hydrogen ion concentration [H

⫹

Must have a raised bicarbonate concentration [HCO

⫺

May have evidence of renal compensation.

May have respiratory failure due to hypoventilation

43. A patient with an uncompensated respiratory alkalosis may have

Been exposed to living at high altitudes.

A reduced [H

]:[HCO

⫺

] ratio.

Neuromuscular hyperexcitability.

An arterial pH of 7.3.

A blood [H

⫹

] of 30 nmol/litre.

MCQ

Body fluids – answers

Answers

38.

True

Since red cells are heavier than plasma.

True

This gives a slightly lower value than centrifugation which traps a little plasma
between cells.

True

Due to loss of plasma and interstitial fluid.

False

It falls as extracellular fluid and hence plasma volume increases.

False

Though individual RBCs are large, total red cell mass is decreased.

39.

False

Healthy normal people do not beneﬁt from vitamin B

supplements.

True

The RBC deﬁcit is corrected by bone marrow stimulation by erythropoietin.

True

The reduced oxygen carrying capacity of the blood causes release of erythropoie-
tin which stimulates RBC stem cells in the bone marrow.

True

The anaemia seen in nephrectomized patients is due largely to lack of erythro-
poietin.

True

A raised reticulocyte count is evidence of a hyperactive bone marrow.

40.

True

The B

/intrinsic factor complex is absorbed in the terminal ileum.

False

Lack of B

results in a macrocytic hyperchromic anaemia.

False

Gastric mucosa atrophy is a cause, not an effect, of B

lack; gastric mucosa nor-

mally produces the ‘intrinsic factor’ required for B

absorption.

True

is used in the DNA synthesis required by platelet precursor cells.

True

Maintenance of myelin in neural sheaths also depends on vitamin B

41.

False

It is consistent with a metabolic alkalosis.

False

A partly compensated acidosis has a low pH.

False

is normally raised in metabolic alkalosis as a compensatory mechanism.

False

All these values are reduced in chronic renal failure.

True

Pyloric obstruction causes a metabolic alkalosis.

42.

True

This is the hallmark of a respiratory acidosis.

False

⫹

] is raised in uncompensated acidosis.

True

The raised [HCO

⫺

] is compensating partly for the raised P

True

The raised [HCO

⫺

], compensating the raised P

is generated by the kidneys.

True

This leads to retention of carbon dioxide.

43.

False

Living at high altitudes induces partial compensation, i.e. fall in [HCO

⫺

]

True

This is consistent with alkalosis.

True

Alkalosis favours the development of tetany by increasing the binding power of
plasma protein for ionic calcium.

False

This is an acidotic pH.

True

The normal level is 40 nmol/litre.

MCQ

Body fluids – questions

Questions 44–49

44. In investigating a patient’s acid-base status

Venous rather than arterial blood should be studied.

Blood samples may be stored for up to 12 hours at room temperature before analysis.

pH can be calculated if [HCO

⫺

] and P

are known.

Raised urinary ammonium salts suggest renal compensation for respiratory acidosis.

An early fall in [HCO

⫺

] suggests that the acid-base disturbance is respiratory in origin.

45. Respiratory alkalosis differs from metabolic alkalosis in that the

Likelihood of tetany is less.

Urine is alkaline.

Arterial blood [HCO

⫺

] is normal or low.

Arterial blood P

is reduced.

Reduction in cerebral blood flow is greater.

46. Rejection of a transplanted organ is made less likely by

Treatment which reduces the blood lymphocyte count.

Keeping the recipient in a germ-free environment.

Irradiation of the transplanted organ with X-rays.

Drugs which interfere with mitosis.

Transplanting between identical twins.

47. Reduction in the neutrophil granulocyte count may be

Caused by drugs suppressing bone marrow activity.

A consequence of tissue damage.

Associated with painful throat ulcers.

Associated with widespread purulent infections.

Caused by high levels of circulating glucocorticoids

48. A fall in plasma sodium concentration

May result from excessive production of ADH.

Decreases intracellular fluid volume.

May occur in people engaged in hard physical work in humid tropical climates.

Reduces plasma osmolality.

Is likely to cause thirst.

49. Sodium retention

Occurs for several days after major surgery.

Occurs in response to secretion of aldosterone, but not cortisol.

Expands the extracellular fluid volume.

Expands the blood volume.

Increases the severity of oedema.

MCQ

Body fluids – answers

Answers

44.

False

Only arterial blood is precisely regulated for [H

⫹

False

Analysis should be prompt; acid-base status is affected by blood cell metabolism.

True

pH is a function of their ratio.

True

Ammonia is secreted to buffer the hydrogen ions being excreted as the kidneys
manufacture bicarbonate.

False

A primary respiratory acid–base problem leads initially to an altered P

45.

False

Both kinds of alkalosis may result in tetany.

False

It is likely to be alkaline in both.

True

[HCO

⫺

] is raised in metabolic alkalosis but falls to compensate for the low P

in respiratory alkalosis.

True

is reduced in respiratory alkalosis but rises to compensate for the high

⫺

] in metabolic alkalosis.

True

The greater fall in P

in respiratory alkalosis causes more cerebral vasoconstric-

tion.

46.

True

T lymphocytes are responsible for tissue rejection.

False

This environment may be necessary because of suppression of the recipient’s
immune responses; it has no bearing on the rejection process.

False

This would not affect the transplant antigens.

True

These suppress the multiplication of lymphocytic stem cells.

True

Identical twins have identical antigens and do not reject each other’s tissues.

47.

True

Granulocytes are formed in the bone marrow.

False

Production of neutrophils increases following tissue damage.

True

Neutrophils are not available to kill bacterial invaders.

False

There will not be much pus since pus consists mainly of dead neutrophils.

False

These suppress lymphocytes and eosinophils.

48.

True

Due to excessive reabsorption of water from the collecting ducts of the nephron.

False

Water is drawn into cells from the hypotonic extracellular fluid; water intoxica-
tion may occur.

True

People sweating heavily may replace their water, but not their salt, deﬁcit; they
tend to get muscle cramps unless they supplement their salt intake.

True

Sodium ions are responsible for nearly half of plasma osmolality.

False

The hypothalamic osmoreceptors responsible for thirst respond to hypertonicity,
not hypotonicity of the ECF.

49.

True

This is part of the metabolic response to trauma.

False

Both have mineralocorticoid effects.

True

Sodium chloride is the ‘skeleton’ of the ECF; chloride and water are retained with
the sodium.

True

Plasma is part of extracellular volume.

True

Oedema fluid is excess interstitial fluid.

MCQ

Body fluids – questions

Questions 50-55

50. Sodium depletion differs from sodium retention in that it causes a

reduction in

Central venous pressure.

Renin production.

The speciﬁc gravity of the blood.

Intracellular fluid volume.

Total body mass.

51. Sodium depletion differs from water depletion in that

Cardiovascular changes are less pronounced.

Intracellular fluid volume is less affected.

The haematocrit increases.

Thirst is more severe.

Antidiuretic hormone levels are higher.

52. Potassium depletion

Can be detected by analysis of a biopsied sample of muscle.

Can result from loss of gastrointestinal secretions.

Causes increased activity of intestinal smooth muscle.

Exacerbates pre-existing acidosis.

Increases T wave amplitude in the electrocardiogram.

53. A high blood potassium level (hyperkalaemia)

Occurs in acute renal failure.

Follows severe crush injuries to the limbs.

May diminish cardiac performance and cause death.

Increases skeletal muscle strength.

May be reduced by intravenous infusion of insulin and glucose.

54. Deficiency of factor VIII (antihaemophilic globulin)

Increases the bleeding time.

Is due to an abnormal gene on the Y chromosome.

To 75 per cent of its normal value results in excessive bleeding after tooth extraction.

Causes small (petechial) haemorrhages into the skin to cause purpura.

Affects the extrinsic, rather than the intrinsic, pathway for blood coagulation.

55. A raised level of calcium in the blood (hypercalcaemia)

May occur when parathyroid activity decreases.

May occur when the plasma protein level falls.

May occur in chronic renal failure.

Causes increased excitability of nerve and muscle.

Increases the risk of stone formation in the urinary tract.

MCQ

Body fluids – answers

Answers

50.

True

Blood volume parallels body sodium levels; it expands with sodium retention and
shrinks with sodium depletion.

False

A reduced blood volume stimulates release of renin.

False

It is increased in sodium depletion due to an increased haematocrit.

False

If anything, ICF volume expands osmotically in sodium depletion.

True

Due to the loss of extracellular fluid in sodium depletion.

51.

False

Blood volume is more reduced with sodium depletion; cardiovascular changes are
more pronounced.

True

Extracellular volume is a function of body sodium content.

False

It increases in both cases.

False

Hypertonicity is the main stimulus causing thirst.

False

Here also, hypertonicity is the main stimulus for ADH secretion.

52.

True

Since most body potassium is intracellular.

True

Gastrointestinal secretions are rich in potassium.

False

Activity decreases and intestinal paralysis (paralytic ileus) may occur.

False

⫹

competes with H

⫹

for excretion in the renal tubules; a low [K

⫹

] favours renal

excretion of H

⫹

ions and this would reduce the severity of acidosis.

False

The amplitude of the T waves decreases.

53.

True

Due to inability to excrete K

⫹

ingested and released from cell breakdown in the

body.

True

Potassium is released from the damaged muscle ﬁbres.

True

Abnormal rhythms and heart failure may result.

False

Both hypo- and hyperkalaemia cause skeletal muscle weakness.

True

This facilitates entry of potassium into cells.

54.

False

Clotting time is increased, but bleeding time is determined by platelets and by
vascular contraction.

False

It is due to a recessive abnormality of the X chromosome.

False

Abnormal bleeding does not occur until the level falls below 50 per cent.

False

Purpura is caused by capillary or platelet disorders.

False

It affects the intrinsic pathway.

55.

False

This reduces blood calcium.

False

This lowers the protein-bound, and hence the total, calcium level.

False

In chronic renal failure PO

retention raises blood PO

levels; Ca

⫹

levels fall to

maintain a constant [Ca

⫹

] [PO

⫺

] product.

False

It depresses excitability.

True

More calcium is ﬁltered and this increases the urinary [Ca

⫹

] [PO

⫺

] solubility

product.

MCQ

Body fluids – questions

Questions 56-57

56. Intravenous infusion of one litre of

Normal (isotonic) saline increases the ECF more than the ICF volume.

10 per cent dextrose provides sufﬁcient energy for a sedentary adult for one day.

A suspension of lipids provides 2–3 times the energy of a suspension of carbohydrates
with the same concentration.

Isotonic (5 per cent) dextrose raises total body water by 1–5 per cent in the average
adult.

An amino acid solution provides between 3–4 times the energy of a carbohydrate solu-
tion with the same concentration.

57. In patients with the acquired immune deficiency syndrome (AIDS)

Neutrophils are more affected than lymphocytes.

Total white cell count is a better indicator of progression than any subset of white cells.

Host DNA is incorporated into the human immunodeﬁciency (HIV) virus.

Occurrence in infancy results from transmission of infection rather than inheritance.

There is increased risk of malignant tumours.

MCQ

Body fluids – answers

Answers

56.

True

Sodium and chloride remain mainly extracellular.

False

It provides less than a quarter of the daily energy requirement.

True

A gram of fat when oxidized liberates 2–3 times the energy liberated by a gram
of carbohydrate.

True

Total body water (about 40 litres) increases to about 41 litres (2.5 per cent
increase).

False

Amino acids and carbohydrates provide similar energy per unit weight but amino
acids are useful for maintaining body tissue proteins.

57.

False

Lymphocytes are more involved than neutrophils with immunity.

False

The CD4 (or T

) count is a major indicator and falls markedly as AIDS progresses.

False

Viral reverse transcriptase incorporates viral RNA into host DNA.

True

In contrast to genetic immune disorders such as X-linked hypogammaglobulinae-
mia.

True

The normal immune system suppresses such tumours.

MCQ

EMQs

Questions 58–67

EMQ Question 58

For each case of disordered haemostasis A–E, select the most appropriate option from the fol-
lowing list of ﬁndings.

1. Capillary abnormality.

2. Deﬁciency of factor VIII.

3. Increased ﬁbrinogen level.

4. Deﬁciency of prothrombin.

5. Deﬁciency of vitamin K.

6. Excessive heparin activity.

7. Massive blood transfusion.

8. Platelet count 90

⫻10

per litre.

9. Platelet count 20

⫻10

per litre.

A 15-year-old child is admitted to hospital with recent onset of widespread purpura
(pin-head areas of haemorrhage into the skin). Laboratory investigations reveal an
abnormality which accounts for the bleeding tendency.

A 50-year-old man is receiving anticoagulant therapy (warfarin, a vitamin K antagonist)
after heart valve replacement. He is admitted to hospital with haematuria (blood in the
urine) and his INR (international normalized ratio, a measure of the prothrombin clot-
ting time in relation to the normal time) is found to be 4.2.

A 90-year-old women has blotchy purple areas about 5 cm diameter on her hands and
arms. They are not uncomfortable and she has no health complaints.

A 70-year-old man is operated on for aneurysm (swelling) of his aorta. Severe bleeding
requires infusion of forty units of blood. His recovery is complicated by a bleeding ten-
dency and he is found to have a very low level of ﬁbrinogen. His treatment includes
administration of heparin.

A 10-year-old child with no known medical problems has been admitted to hospital for
persistent bleeding after tooth extraction. Haemostasis had been achieved initially after
the extraction but subsequently prolonged oozing from the tooth socket began.

EMQ

BODY FLUIDS

Body fluids – answers

Answers for 58

Option 9

Platelet count 20

⫻10

per litre. Widespread purpura is due to failure of

platelet plugging of capillaries and may be due to a low platelet count or to capillary
abnormality. An abnormal laboratory test to account for this would be a low platelet
count. Although both those given are below normal, only values below 20–40

⫻10

per

litre account for serious bleeding.

Option 4

Deﬁciency of prothrombin. The action of warfarin, a vitamin K antagonist,

is to impair formation of several coagulation factors, notably prothrombin. There are a
number of cardiological indications for the use of warfarin, including heart valve replace-
ment. The value quoted is above the usual recommended range and the prolonged pro-
thrombin time due to a low level of prothrombin would account for the bleeding.

Option 1

Capillary abnormality. With advancing age, capillaries like tissues generally

become less resilient in the face of stress such as a relatively high internal pressure. This
leads randomly to patchy areas of bleeding such as those described. Apart from their
appearance they cause no problems.

Option 7

Massive blood transfusion. Massive blood transfusion may lead to wide-

spread activation of the coagulation mechanism – diffuse intravascular coagulopathy. This
in turn causes so much deposition of ﬁbrin that the circulating ﬁbrinogen level falls to
levels which result in a bleeding tendency. Paradoxically heparin, by preventing the
abnormal coagulation, allows the ﬁbrinogen level to rise and can relieve the condition.

Option 2

Deﬁciency of factor VIII. This condition (haemophilia) does not interfere

with initial haemostasis due to vascular closure, so the bleeding time is normal as in this
case. However, when the vascular spasm wears off, failure to clot is revealed as a persis-
tent ooze of blood. Treatment is by supplying the missing factor VIII.

EMQ

Body fluids – questions

EMQ Question 59

For each case of disturbed acid–base balance A–E, select the most appropriate option from the
following list of results of arterial blood analysis.

HCO

(kPa)

(mmol/l.)

7.15

7.4

7.25

7.55

7.2

100 mmHg

⫽13.3 kPa

A 60-year-old woman who suffers from long standing chronic bronchitis has just been
admitted to hospital because her condition deteriorated when she developed a chest
infection. No treatment had been given before the blood sample was taken.

A 50-year-old man with long-standing chronic bronchitis has been in hospital for sev-
eral days for treatment of an exacerbation. He is receiving oxygen therapy but his con-
dition is deteriorating.

A 50-year-old woman with long-standing renal disease has been admitted with deteri-
oration of her condition, including marked drowsiness. She is noticed to be hyperventi-
lating.

A 25-year-old man is taking part in a mountain climbing expedition in the Himalayas
and the medical ofﬁcer of the team is carrying out physiological measurements. The
subject has been through the usual protocol for acclimatization to high altitude.

A 30-year-old man has been admitted to hospital suffering from abdominal pain and
general malaise. He has long-standing upper abdominal pain for which he has been
treating himself for some years with quite large amounts of sodium bicarbonate which
rapidly relieves the pain. He has begun to get muscle spasms in his hands and feet.

EMQ

Body fluids – answers

Answers for 59

Option 3

This patient has features suggesting respiratory failure – drowsiness and

cyanosis in someone with chronic obstructive airways disease. So we are looking for signs
of a respiratory acidosis – low pH due to high carbon dioxide levels and a reduced oxygen
level to account for the cyanosis. Only Option 3 has these three features. In someone with
a long-standing respiratory acidosis the bicarbonate is usually raised as in this case (for
comparison, results in Option 2 are all average normal).

Option 6

This patient is very similar to the one above except that he has been receiv-

ing oxygen therapy for his hypoxic hypoxia. Deterioration on oxygen suggests the pos-
sibility that complete relief of the hypoxia has resulted in respiratory depression with a
rising carbon dioxide level and worsening respiratory acidosis. Results in Option 6 conﬁrm
this with the very high oxygen pressure which can be produced by breathing oxygen
together with a high carbon dioxide level and a dangerously low pH. Correct therapy is to
give controlled oxygen at, for example, 24–28 per cent and monitor the blood gases so
that the oxygen level is above dangerous levels but the carbon dioxide does not rise dan-
gerously.

Option 1

This patient has the symptoms of severe renal failure, a condition which

leads to a non-respiratory (or metabolic) acidosis. This is conﬁrmed by the very low bicar-
bonate level and the very low pH. Such a condition leads to respiratory compensation by
hyperventilation to lower the carbon dioxide level as shown. The hyperventilation also
raises the oxygen level towards that in the atmosphere.

Option 4

High altitudes lead to hyperventilation triggered by the carotid bodies in

response to hypoxic hypoxia. The hyperventilation improves the oxygen level (which is
still below that at sea level) but produces a respiratory alkalosis due to washout of carbon
dioxide. With acclimatization the kidney responds by lowering the bicarbonate level by
reducing tubular secretion of the now scarce hydrogen ions.

Option 5

This is now a rather rare cause of metabolic alkalosis – ingestion of large

amounts of sodium bicarbonate which relieves ulcer pain by temporarily buffering the
gastric acid. However the bicarbonate is absorbed and can lead to a metabolic alkalosis.
Alkalosis increases the binding of available calcium ions in the blood by plasma proteins
and can lead to tetany, which usually starts in adults with ‘carpo-pedal’ spasm. Metabolic
alkalosis is compensated by depression of respiration, allowing the carbon dioxide level
to rise and balance the increased bicarbonate level. The oxygen pressure tends to fall with
the hypoventilation.

EMQ

Body fluids – questions

EMQ Question 60

For each case of fluid balance disturbance A–E, select the most appropriate option from the
following list.

1. Increased total body water.

2. Decreased total body water.

3. Increased extracellular fluid.

4. Decreased extracellular fluid.

5. Increased interstitial fluid.

6. Decreased interstitial fluid.

7. Increased blood volume.

8. Decreased blood volume.

9. Increased plasma volume.

10. Decreased plasma volume.

A 20-year-old mentally disturbed patient has refused all food and drink for several
days. Urine volume has fallen to around 100 ml in ﬁve hours. Plasma osmolality has
risen to 320 mosmol per litre (previously 290 mosmol per litre).

A 50-year-old man has suffered from vomiting and diarrhoea for several days. His
peripheries are cold and he has a heart rate of 120 per minute and an arterial blood
pressure of 90/65.

A 50-year-old woman is suffering from weakness and mild confusion. She is found to
have a plasma sodium level of 125 mmol/litre (normal about 140 mmol/litre) and has a
raised level of vasopressin (antidiuretic hormone).

An 80-year-old woman has been admitted to hospital after vomiting blood. Following
transfusion of several pints of blood she has become breathless and is found to have an
increased jugular venous pressure.

A 40-year-old man has been admitted to hospital with full thickness burns of 40 per
cent of his body surface. Next day his blood pressure has fallen. A blood test shows a
haematocrit of 54 per cent.

EMQ

Body fluids – answers

Answers for 60

Option 2

Decreased total body water. In the absence of any water intake, a person

loses a minimum of around 1500 ml per day (500 ml insensible loss from the lungs,
500 ml insensible loss from the skin and 500 ml as the minimum amount of water which
can dissolve excreted solid waste products in the urine). A urine volume of 100 ml in ﬁve
hours conﬁrms this condition. After several days there will be a water deﬁcit of around
four to ﬁve litres or 10 per cent of total body water, so the osmolality has risen by about
10 per cent. The water deﬁcit is distributed between intracellular and extracellular fluid
and oral water would correct the deﬁcit.

Option 4

Decreased extracellular fluid. The patient has lost a considerable volume of

intestinal secretions. This fluid is isotonic and rich in sodium and chloride, the main extra-
cellular ions. His main depletion is of extracellular fluid and this is conﬁrmed by signs of
severe peripheral circulatory failure evidenced by a low arterial blood pressure despite
vasoconstriction (cold peripheries) and a rapid heart rate. He urgently needs replenishment
of his extracellular fluid by intravenous infusion of isotonic (normal) saline. Although
Option 8 accounts for the peripheral circulatory failure, Option 4 is more appropriate as it
includes the underlying mechanism and points to the appropriate treatment.

Option l

Increased total body water. Inappropriately raised secretion of antidiuretic

hormone causes excessive reabsorption of water as fluid passes through the collecting
ducts. This dilutes all body fluids as indicated by the low sodium level (osmolality would
be correspondingly reduced). The waterlogging of the body cells impairs function and this
effect in the brain is manifested by confusion. Restricted water intake would improve the
condition.

Option 7

Increased blood volume. Replacement of blood loss is urgent in the elderly,

but over-transfusion can increase the blood volume above normal. In the elderly there is
an increased risk of heart failure and increasing the blood volume can precipitate this so
that the heart cannot adequately clear the venous return. The ﬁlling pressure of the two
sides of the heart increases, causing pulmonary oedema and breathlessness plus increased
systemic venous pressure. Diuretic therapy would reduce blood volume by causing excre-
tion of salt and water, thereby lowering extracellular fluid volume.

Option 10

Decreased plasma volume. By damaging capillaries, burns cause increased

loss of fluid and proteins from the circulation. In addition large amounts of interstitial
fluid are lost through the damaged skin. Both effects lower plasma volume, raising the
haematocrit. Low blood volume can lead to peripheral circulatory failure. The standard
treatment is to infuse large quantities of normal saline, in proportion to the area of seri-
ously burnt skin.

EMQ

Body fluids – questions

EMQ Question 61

For each blood transfusion problem A–E, select the most appropriate option from the follow-
ing list.

1. ABO incompatibility.

2. Rhesus incompatibility.

3. Major incompatibility.

4. Minor incompatibility.

5. Multiple repeated transfusions.

6. Massive blood transfusion.

7. Use of stored blood.

8. Use of fresh blood.

A patient has been given three units of blood during a surgical operation. Just after the
operation the patient is at risk of inadequate tissue oxygenation despite satisfactory
arterial blood pressure, haemoglobin and arterial blood oxygen saturation levels.

A patient has been given two units of blood on the day before a planned surgical oper-
ation. Towards the end of the transfusion the patient was noted to have mild fever, and
the next morning slight jaundice was noted in the conjunctivae.

A patient admitted with vomiting of blood shows signs of circulatory failure and is
given a unit of blood quite rapidly. As the transfusion is nearly completed it is discov-
ered that there has been confusion between two patients with exactly the same ﬁrst and
second names and the patient with the transfusion appears much more unwell than at
the start of the transfusion. In fact the group B patient was given group A blood.

During emergency surgery for a dissected aortic aneurysm, a condition notorious for
severe bleeding during operation, a patient is transfused with 20 units of blood. Despite
restoration of a normal blood volume this patient is at risk of hypothermia, tissue
hypoxia and coagulation problems.

A patient with failure of bone marrow function causing aplastic anaemia is admitted for
transfusion as the haemoglobin level has fallen to an unacceptable level. The blood
bank report difﬁculty in ﬁnding suitable red cells due to problems with some of the
‘minor’ blood groups, M and Kell.

EMQ Question 62

For each case of anaemia A–E, select the most appropriate option from the following list.

1. Iron deﬁciency anaemia.

2. Pernicious anaemia.

3. Microcytic anaemia.

4. Macrocytic anaemia.

5. Normocytic anaemia.

6. Bone marrow disease.

7. Compensatory rise in cardiac output.

8. Decreased blood viscosity.

9. Haemolytic anaemia.

10. Increased bone marrow activity.

Normal under the microscope. The mean red cell volume is normal at 90 cubic microns.

A patient with long-standing indigestion has noticed increasing lack of energy and tir-
edness when walking uphill. On questioning he has noticed that the bowel motions are
unusually dark from time to time. Due to the indigestion the patient takes a bland diet
without much meat or vegetables.

A patient with a blood haemoglobin concentration of 60 grams per litre complains of
recent palpitations (an abnormal awareness of the heart beat, often rather fast). When at
rest, the pulse is 110 per minute and the blood pressure 140/60 mmHg.

A woman of 75 has noticed unusual lack of energy recently and feels she is paler than
usual. Her haemoglobin level is 110 grams per litre and the red cell count is depressed
beyond that expected with the fall in haemoglobin. The circulating level of vitamin B

is very low, but the folate level is normal.

A patient with moderate anaemia is found to have a bruit (abnormal murmur) when a
stethoscope is used to listen over each of the carotid arteries in the neck. The doctor is
inclined to attribute the murmur to a physical effect of the anaemia on the blood rather
than to an abnormality of the carotid arteries.

EMQ

Body fluids – answers

Answers for 61

Option 7

Use of stored blood. This blood has the characteristic property of stored

blood – a low level of 2:3-DPG. Hence the blood oxygen dissociation curve is shifted to
the left, and the blood does not give up adequate oxygen at tissue oxygen tensions.

Option 4

Minor incompatibility. There has been a mild antibody rejection of the

donor red cells. A relatively small number of these have been broken down (lysed) to
release bilirubin which causes the jaundice. The immune response also releases products,
including interleukin-1, which cause the fever.

Option 3

Major incompatibility. This type of mistake carries a high risk of death

because the recipient’s naturally occurring anti-A antibody (agglutinin) rapidly destroys
the transfused group A red cells, releasing huge amounts of deadly toxins.

Option 6

Massive blood transfusion. A massive blood transfusion is deﬁned as one

where the volume of blood transfused equals or exceeds the patient’s original blood
volume. Stored blood carries the problem mentioned in (A) but because large volumes of
blood must be given very rapidly there is not time to heat them to body temperature from
their initial low temperature, so the patient’s core temperature drops (hypothermia). This
compounds the shift in the blood oxygen dissociation curve and also slows the coagula-
tion reactions.

Option 5

Multiple repeated transfusions. Such patients require regular blood trans-

fusions on repeated occasions, so their immune system builds up antibodies to minor
blood group antigens such as M, N, Kell and Duffy.

Answers for 62

Option 5

Normocytic anaemia. The haemoglobin concentration is about half normal,

indicating moderate anaemia. Since the red cells look normal and mean cell volume is also
normal this is a normocytic anaemia. It could be due to bone marrow disease, lack of
erythropoietin or other chronic disease.

Option 1

Iron deﬁciency anaemia. This patient has symptoms of anaemia, along with

a suggestion of repeated bleeding into the bowel and a diet likely to be low in iron. The
most likely explanation is anaemia due to iron deﬁciency. This is likely to be a microcytic
anaemia, but no conﬁrmatory details of the presence of small pale red cells are given in
this case.

Option 7

Compensatory rise in cardiac output. This patient has severe anaemia. In

order to provide adequate oxygen for the tissues, the low oxygen content per litre must
be compensated by increased flow. This patient shows the features – fast pulse, high pulse
pressure – of an increased resting cardiac output (hyperdynamic circulation).

Option 2

Pernicious anaemia. This patient has moderately severe anaemia. Because

the red cell count is disproportionately low, the cells must be larger than normal – macro-
cytic. This is explained by the low level of vitamin B

and the normal folate excludes

another major macrocytic anaemia. The B

deﬁciency at this age is usually due to failure

of the stomach to produce intrinsic factor – pernicious anaemia. The term pernicious was
used because before the discovery of vitamin B

there was no treatment and the condi-

tion got worse and worse until the patient died from an extremely low level of haemo-
globin.

Option 8

Decreased blood viscosity. A bruit or murmur in the circulation indicates tur-

bulent flow. Turbulent flow is much more likely as the viscosity of blood decreases. Since
most of the blood viscosity is due to the haematocrit, moderate anaemia could reduce the
viscosity by around half. The increased velocity of flow due to the increased cardiac
output mentioned in (C) would also increase the chance of turbulence.

EMQ

Body fluids – questions

EMQ Question 63

For each lipid-related topic A–E, select the most appropriate option from the following list.

1. Coronary artery disease risk factor.

2. Source of energy.

3. Cell membrane solubility.

4. Cell membrane structure.

5. Metabolic energy per unit mass.

6. Derived from cholesterol.

7. Body lipid stores.

8. Lipase.

9. Carbohydrate hormones.

10. Protein hormones.

When explorers were crossing Antarctica trailing all their food in a hand sleigh there
was an advantage in taking a high proportion of fat rather than carbohydrate.

Oestradiol, testosterone and aldosterone share a property which is not shared by insulin
and vasopressin.

In life-threatening acute inflammation of the pancreas (pancreatitis) considerable tissue
damage is produced by a chemical which is detected in the bloodstream in large
amounts.

In patients who have had a heart attack due to blockage of the blood supply of the
myocardium, drugs may be given to lower the blood cholesterol level.

The interior of muscle ﬁbres contains many glycogen granules and lipid droplets.

EMQ Question 64

For each of the descriptions A–E, select the most appropriate option from the following list.

1. Neutrophil polymorphonuclear

2. Platelet.

granulocyte.

3. Lymphocyte.

4. Thrombocytopoenia.

5. Leukaemia.

Responsible for ingesting invading bacteria.

The blood cell most affected by AIDS.

A condition where abnormal white cells invade the bone marrow.

The smallest cellular element in the blood.

Uniquely capable of becoming sticky.

EMQ Question 65

For each of the descriptions related to body fluids A–E, select the most appropriate option from
the following list.

1. Osmolality.

2. Plasma albumin.

3. Glucose.

4. Sodium.

5. Plasma globulin.

Responsible for most of the colloid osmotic pressure of the plasma.

Responsible for fluid shifts between intracellular and extracellular fluid.

Provides about half of osmotically active particles in extracellular fluid.

Mainly responsible for opposing the leak of fluid out of capillaries.

Determines the freezing point of a solution.

EMQ

Body fluids – answers

Answers for 63

Option 5

Metabolic energy per unit mass. Fat liberates just over twice the metabolic

energy per unit mass that is liberated by metabolism of carbohydrates. The two substrates
are both used by the body to provide energy especially in strenuous exercise. So by drag-
ging relatively large amounts of fat the explorers were minimizing the load on their sleigh
and maximizing the energy they obtained from their food.

Option 6

Derived from cholesterol. Oestradiol, testosterone and aldosterone are all

derived in the body from cholesterol. Despite being a risk factor for arterial disease when
present in excess in the blood, cholesterol is a precursor of vital hormones and is synthe-
sized in the body. Insulin is a protein hormone and vasopressin a polypeptide hormone.

Option 8

Lipase. In acute pancreatitis large amounts of lipase escape into the blood

and this leads to widespread fat necrosis as part of the life-threatening state when the pan-
creatic hormones enter the bloodstream.

Option 1

Coronary artery disease risk factor. Excessive lipids in the blood, including

cholesterol, are a risk factor for coronary atheroma. The lipid proﬁle may also be improved
by moderate exercise and avoidance of obesity.

Option 2

Source of energy. During prolonged exercise energy is derived in approxi-

mately equal amounts from carbohydrate and fat. The glycogen granules in particular are
a major source of energy. They become more prominent with physical training and are
depleted after prolonged fasting exercise.

Answers for 64

Option 1

Neutrophil polymorphonuclear granulocyte. These are the commonest of the

white cell types. In an area of serious prolonged infection the ‘neutrophils’ ingest bacte-
ria, eventually die and accumulate as pus.

Option 3

Lymphocyte. The lymphocytes are responsible for immunity, so a disease

which damages their function leads to immune deﬁciency.

Option 5

Leukaemia. Leukaemia is a cancerous multiplication of abnormal white cells

which replace normal bone marrow cells, suppressing normal formation of white cells, red
cells and other marrow-derived cells.

Option 2

Platelet. Platelets are about half the diameter of red cells, which in turn are

smaller than white cells. Lack of platelets is called thrombocytopoenia.

Option 2

Platelet. Areas of endothelial damage expose collagen to which platelets are

attracted. They adhere to the collagen and become sticky for other platelets so that a plate-
let plug develops to close the gap and prevent loss of blood.

Answers for 65

Option 2

Plasma albumin. Colloid osmotic pressure is due to protein molecules which

cannot readily cross the capillary wall; albumin constitutes the larger portion of the
plasma protein mass, its molecules are smaller than globulin so it exerts much more
osmotic pressure.

Option 1

Osmolality. Water passes across the cell wall by osmotic forces due to the

sum of the effects of all dissolved particles – the osmolality.

Option 4

Sodium. Sodium has a concentration around 135 mmol per litre and pro-

vides nearly half of the total osmolality of around 285 mosmol per kg.

Option 2

Plasma albumin. Because most particles are in equilibrium across the capil-

lary wall they do not contribute to the osmotic force opposing fluid leak. The proteins pro-
vide an opposing force and albumin is the commonest protein particle.

Option 1

Osmolality. Osmolality can be measured by noting the freezing point of the

solution being tested.

EMQ

Body fluids – questions

EMQ Question 66

For each of the intravenous fluids A–E, select the most appropriate option from the following
list of infusions.

1. 50 per cent glucose.

2. 1.8 per cent saline.

3. 5 per cent glucose (dextrose).

4. Normal (0.9 per cent) saline (sodium

5. 8.4 per cent sodium bicarbonate.

chloride).

An isotonic solution which expands mainly the extracellular fluid volume.

An isotonic solution which expands both intra- and extracellular fluid volumes.

A major nutrient used in intravenous nutrition.

A hypertonic fluid with about twice the osmolality of plasma.

A fluid occasionally used to treat severe acidosis.

EMQ Question 67

For each of the body fluid disturbances A–E, select the most appropriate option from the fol-
lowing list of abnormalities.

1. Hyper-osmolality.

2. Hypo-osmolality.

3. Hyponatraemia.

4. Hyperkalaemia.

5. Raised haematocrit.

Excessive retention of water by the kidneys.

Excessive loss of plasma and extracellular fluid as a result of severe burns.

Likely to be present if the blood glucose level is 30 (normal 5–8) mmol/litre.

Produced by drinking excessive amounts of water.

Likely to cause swelling of brain cells.

EMQ

Body fluids – answers

Answers for 66

Option 4

Normal saline. Normal saline has the same tonicity (osmolality) as plasma

and extracellular fluid. Sodium doesn’t enter intracellular fluid appreciably. The chloride
and water remain with the sodium in the extracellular space.

Option 3

5 per cent glucose. 5 per cent glucose (dextrose) is also isotonic. It has the

same number of particles as 0.9 per cent saline. Saline dissociates so the average particle
molecular weight is about 30. Dextrose has a molecular weight of 180 and does not dis-
sociate so about six times the mass of dextrose is required for isotonicity.

Option 1

50 per cent glucose. A litre of 50 per cent glucose contains 500 grams of

glucose, yielding about 2000 kilocalories (about 9 megajoules, MJ), around the resting
daily requirement of an adult.

Option 2

1.8 per cent saline. This is twice the osmolality of normal saline – around

600 as compared with around 300 mosmoles per kg.

Option 5

8.4 per cent sodium bicarbonate. This concentrated bicarbonate solution has

a high buffering capacity for hydrogen ions. However correcting acid–base balance is a
complex procedure rarely beneﬁting from such drastic measures.

Answers for 67

Option 2

Hypo-osmolality. Excessive retention of water dilutes all the body fluids

leading to hypo-osmolality. Water crosses the cell membrane until equilibrium is attained.
Inappropriately high levels of antidiuretic hormone could do this.

Option 5

Raised haematocrit. As fluid is lost, plasma volume declines, so the red

blood cells become an increasing proportion of blood volume.

Option 1

Hyper-osmolality. The high glucose raises the osmolality proportionately, so

a rise of 25 mmol/litre in the extracellular glucose level would raise the osmolality from
285 to 310 mosmol/kg, an appreciable rise. This would draw fluid from cells, including
brain cells, disturbing function.

Option 2

Hypo-osmolality. Drinking excessive amounts of water has the same effect

as excessive retention by the kidney. However healthy people promptly excrete the excess
fluid.

Option 2

Hypo-osmolality. Excess water is drawn into brain cells by osmosis. This also

disturbs brain function.

EMQ

CARDIOVASCULAR SYSTEM

MCQs

Questions 68–72

68. Coronary blood flow to the left ventricle increases during

Early systole.

Myocardial hypoxia.

Hypothermia.

Stimulation of sympathetic nerves to the heart.

Arterial hypertension.

69. Local metabolic activity is the chief factor determining the rate of blood

flow to the

Heart.

Skin.

Skeletal muscle.

Lung.

Kidney.

70. The pressure

Drop along large veins is similar to that along large arteries.

Drop across the hepatic portal bed is similar to that across the splenic vascular bed.

In the hepatic portal vein exceeds that in the inferior vena cava.

Drop across the vascular bed in the foot is greater when a subject is in the vertical than
when he is in the horizontal position.

In foot veins is lower when walking than when standing still.

71. The second heart sound differs from the first heart sound in that it is

Related to turbulence set up by valve closure.

Longer lasting than the ﬁrst sound.

Higher in frequency.

Occasionally split.

Heard when the ventricles are relaxing.

72. Pulmonary vascular resistance is

Less than one-third that offered by the systemic circuit.

Decreased when alveolar oxygen pressure falls.

Expressed in units of volume flow per unit time per unit pressure gradient.

Decreased during exercise.

Regulated reflexly by sympathetic vasoconstrictor nerves.

MCQ

Cardiovascular system – answers

Answers

68.

False

It falls; coronary vessels are compressed by the contracting myocardium.

True

A fall in P

has a potent vasodilator effect on coronary vessels. Adenosine

released from hypoxic myocardium is also a potent vasodilator.

False

The fall in metabolic rate and cardiac output in hypothermia reduce cardiac work
and lead to a reduction in coronary blood flow.

True

Sympathetic stimulation increases the rate and force of contraction; the resulting
increase in the rate of production of vasodilator metabolites dilates coronary ves-
sels.

True

Myocardial work and metabolism are increased in hypertension.

69.

True

There is a close relationship between the work of the heart and coronary flow.

False

Skin blood flow is geared mainly to thermoregulation and normally exceeds that
needed for skin’s modest metabolic requirements.

True

Local blood flow is largely determined by the vasoactive metabolites such as
rising P

, H

⫹

concentration and falling P

. The changes produced by vaso-

motornerves are small compared with those produced by metabolites.

False

The entire cardiac output must pass through the lungs regardless of the local
metabolic needs of the pulmonary tissues. It is greatly in excess of the lungs’
metabolic needs.

False

As in skin, renal blood flow (about one quarter of total cardiac output) greatly
exceeds local metabolic needs. The blood is sent to the kidneys for processing.

70.

True

About 10 mmHg or less; both offer little resistance to flow.

False

The drop across the splenic vascular bed (about 60 mmHg) is much larger; the
hepatic portal bed offers little resistance to flow.

True

Otherwise blood would not flow through the portal bed.

False

Changing from the horizontal to the vertical position increases arterial and
venous pressures equally.

True

The muscle pump in the leg decreases venous pressure.

71.

False

This applies to both heart sounds.

False

It is about 20 per cent shorter.

True

About 50 Hz compared with 35 Hz for the ﬁrst sound.

False

Both may be split due to asynchronous valve closure.

True

The ﬁrst sound is due to ventricular systole; the second occurs during ventricu-
lar relaxation when the aortic valves snap shut as ventricular pressure falls below
aortic.

72.

True

The pressure head needed to drive cardiac output through the pulmonary circuit
(about 15 mmHg) is much less than that needed in the systemic circuit (about
90 mmHg).

False

The reverse is true; low alveolar P

may cause pulmonary hypertension.

False

These are conductance units, the reciprocal of resistance units.

True

Thus there is little rise in pulmonary arterial pressure during exercise despite the
increased flow rate. Release of nitric oxide from the pulmonary vascular endo-
thelium may account for the vasodilatation.

False

Pulmonary vascular resistance is controlled by local rather than by nervous
mechanisms.

MCQ

Cardiovascular system – questions

Questions 73–78

73. Ventricular filling

Depends mainly on atrial contraction.

Begins during isometric ventricular relaxation.

Gives rise to a third heart sound in some healthy people.

Can occur only when atrial pressure is greater than atmospheric pressure.

Is most rapid in the ﬁrst half of diastole.

74. Veins

Contain most of the blood volume.

Have a sympathetic vasoconstrictor innervation.

Receive nutrition from vasa vasorum arising from their lumen.

Respond to distension by contraction of their smooth muscle.

Undergo smooth muscle hypertrophy when exposed to high pressure through an arterio-
venous ﬁstula.

75. In the heart

The left atrial wall is about three times thicker than the right atrial wall.

Systolic contraction normally begins in the left atrium.

Excitation spreads directly from atrial muscle cells to ventricular muscle cells.

Atrial and ventricular muscle contracts simultaneously in systole.

The contracting ventricles shorten from apex to base.

76. Isometric (static) exercise differs from isotonic (dynamic) exercise in that

it causes a greater increase in

Venous return.

Pressure in the veins draining the exercising muscle.

Muscle blood flow.

Mean arterial pressure.

Cardiac work for the same increase in cardiac output.

77. The net loss of fluid from capillaries in the legs is increased by

Arteriolar dilation.

Change from the recumbent to the standing position.

Lymphatic obstruction.

Leg exercise.

Plasma albumin depletion.

78. When measuring blood pressure by the auscultatory method

The sounds that are heard are generated in the heart.

The cuff pressure at which the ﬁrst sounds are heard indicate systolic pressure.

The cuff pressure at which the loudest sounds are heard indicate diastolic pressure.

Systolic pressure estimations tend to be lower than those made by the palpatory
method.

Wider cuffs are required for larger arms.

MCQ

Cardiovascular system – answers

Answers

73.

False

Atrial contraction accounts for only about 20 per cent of ﬁlling at rest.

False

During this phase the AV valves are closed and ventricular volume is constant.

True

This low-pitched sound is sometimes heard in early diastole.

False

Filling occurs when atrial pressure exceeds ventricular pressure.

True

Due to entry of blood accumulated in the atria during ventricular systole.

74.

True

Around three-quarters; veins are referred to as ‘capacitance’ vessels.

True

These modulate venous capacity.

False

Their vasa arise from neighbouring arteries.

True

This ‘myogenic’ response helps to limit the degree of distension.

True

Another functional adaptation to resist distension.

75.

False

Their wall thickness is similar since the workload of the two atria is similar.

False

It begins at the sinuatrial node in the right atrium.

False

Excitation can only pass from atria to ventricles via specialized conducting tissue
in the AV bundle.

False

Delay of excitation in the AV bundle makes atrial precede ventricular contraction.

True

Due to the spiral arrangement of some muscle ﬁbres; circular ﬁbres reduce ven-
tricular circumference.

76.

False

The muscle pump is more effective in dynamic than in static exercise.

True

In dynamic exercise, the muscle pump increases venous return and so decreases
venous pressure in dependent veins.

False

The increase is less since inflow is obstructed by the sustained compression
exerted by the contracting muscle.

True

There is relatively little fall in total peripheral resistance with static exercise.

True

The rise in arterial pressure with static exercise increases cardiac work since car-
diac output has to be ejected against a higher aortic pressure.

77.

True

This increases capillary hydrostatic pressure.

True

In the standing position, capillary pressure increases by the hydrostatic equiva-
lent of the column of blood below the heart.

False

Lymphatic obstruction allows tissue fluid to accumulate; the rise in interstitial
pressure reduces the capillary transmural hydrostatic pressure gradient.

True

Capillary pressure rises during the exercise hyperaemia.

True

Hypoproteinaemia decreases the transmural colloid osmotic pressure gradient.

78.

False

Korotkoff sounds are produced locally by the turbulence of blood being forced
past the narrow segment of a partially occluded artery.

True

The sharp taps of Phase 1 are generated as the systolic pressure peaks force blood
under the cuff.

False

Sudden muffling (Phase 4) or disappearance (Phase 5) of the sounds indicate the
diastolic pressure point.

False

They are usually higher since palpation may fail to detect the ﬁrst tiny pulses.

True

Otherwise the full cuff pressure may not be transmitted to the artery.

MCQ

Cardiovascular system – questions

Questions 79–84

79. The absolute refractory period in the ventricles

Is the period when the ventricles are completely inexcitable.

Corresponds to the period of ventricular depolarization.

Corresponds approximately to the period of ventricular contraction.

Is shorter than the corresponding period in atrial muscle.

Decreases during sympathetic stimulation of the heart.

80. Vascular resistance

Increases by 50 per cent when the vascular radius is halved.

Is related to the thickness of the wall of the vessel.

Is related to the vessel’s length.

Is affected by blood viscosity.

Is greater in the capillary bed than in the arteriolar bed.

81. Sympathetic drive to the heart is increased

In exercise.

In excitement.

In hypotension.

When parasympathetic drive is decreased.

During a vasovagal attack.

82. In an adult subject standing quietly at rest, venous pressure in the

Foot is approximately equal to arterial pressure at heart level.

Thorax decreases when the subject inhales.

Hand is subatmospheric when the hand is raised above the head.

Venous sinuses of the skull are subatmospheric.

Superior vena cava is an index of cardiac ﬁlling pressure.

83. Hyperaemia in skeletal muscle during exercise is normally associated with

Release of sympathetic vasoconstrictor tone in the exercising muscles.

Capillary dilation due to relaxation of capillary smooth muscle.

A fall in arterial pressure.

Reflex vasoconstriction in other vascular beds.

An increase in cardiac output.

84. Sinuatrial node cells are

Found in both atria.

Innervated by the vagus.

Unable to generate impulses when completely denervated.

Connected to the AV node by ﬁne bundles of Purkinje tissue.

Able to generate impulses because their membrane potential is unstable.

MCQ

Cardiovascular system – answers

Answers

79.

True

This is the deﬁnition.

True

Depolarized cells cannot be excited.

True

This prevents tetanic contraction of the heart.

False

It is longer, as is the duration of its depolarization.

True

Shortening the refractory period permits higher heart rates.

80.

False

By more than 90 per cent; resistance is related to the fourth power of the radius.

False

Vascular resistance is not related to wall thickness.

True

It is directly proportional to length.

True

Resistance is related to Viscosity

⫻Length/Radius

False

Total arteriolar resistance exceeds total capillary resistance though the reverse is
true for single vessels.

81.

True

␤-adrenergic blocking drugs reduce exercise tachycardia.

True

The tachycardia during excitement is also reduced by

␤-blocking drugs.

True

A reflex response to decreased stretch of arterial baroreceptors.

False

The two systems can function independently.

False

Parasympathetic drive slows the heart during a vasovagal attack; sympathetic
drive may stimulate the heart during recovery.

82.

True

It is about 90 mmHg, due to the column of blood (about 1 metre) between the
heart and the foot.

True

The negative intrathoracic pressure during inhalation is transmitted to the veins.

False

Limb veins collapse above heart level. Negative pressure cannot be transmitted
along a collapsed tube so venous pressure is atmospheric in the raised hand.

True

The sinuses are held open by their meningeal attachments and cannot collapse.

True

A central venous pressure line is usually placed here.

83.

False

Exercise hyperaemia occurs normally in sympathectomized muscles.

False

True capillaries have no smooth muscle; they dilate passively with the rise in
capillary pressure due to active arteriolar dilation.

False

Arterial pressure usually rises.

True

Vasoconstriction in kidneys, gut and skin prevent excessive falls in total periph-
eral resistance.

True

This, together with the reflex constriction above, compensate for the fall in mus-
cular vascular resistance and thus prevent arterial pressure falling during exer-
cise.

84.

False

The SA node is in the right atrium near its junction with the superior vena cava.

True

Vagal activity slows the rate of impulse generation and thus the heart rate.

False

The SA node has intrinsic rhythmicity and can generate impulses independently.

False

Purkinje tissue is conﬁned to the ventricles; atrial ﬁbres conduct impulses from
the SA to the AV node.

True

Impulse generation is due to spontaneous diastolic depolarization of the cells.

MCQ

Cardiovascular system – questions

Questions 85–91

85. The first heart sound corresponds in time with

Closure of the aortic and pulmonary valves.

The P wave of the electrocardiogram.

A rise in atrial pressure.

A rise in ventricular pressure.

The A wave in central venous pressure.

86. Increased sympathetic drive to the heart increases the

Rate of diastolic depolarization in sinuatrial node cells.

Coronary blood flow.

Rate of conduction in Purkinje tissue.

Slope of the Frank–Starling (work versus stretch) curve of the heart.

Ejection fraction of the left ventricle.

87. The velocity of blood flow

In capillaries is low because they offer high resistance to flow.

In veins is greater than in venules.

Can fall to zero in the ascending aorta during diastole.

Is greater towards the centre of large blood vessels than at the periphery.

In the circulation falls as the haematocrit falls.

88. The strength of contraction of left ventricular muscle increases when

End-diastolic ventricular ﬁlling pressure rises.

Serum potassium levels rise.

Blood calcium levels fall.

Strenuous exercise is undertaken.

Peripheral resistance is increased as in hypertension.

89. During isometric ventricular contraction

The entry and exit valves of the ventricle are closed.

Pressure in the aorta rises.

Pressure in the atria falls.

Left coronary blood flow falls.

The rate of rise in pressure is greater in the right than in the left ventricle.

90. In the electrocardiogram, the

QRS complex follows the onset of ventricular contraction.

T wave is due to repolarization of the ventricles.

PR interval corresponds with atrial depolarization.

RT interval is related to ventricular action potential duration.

R-R interval normally varies during the respiratory cycle.

91. Cardiac output

Is normally expressed as the output of one ventricle in litres/minute.

May not increase when heart rate rises.

Usually rises when a person lies down.

Rises in a hot environment.

Does not increase in exercise following denervation of the heart.

MCQ

Cardiovascular system – answers

Answers

85.

False

It is synchronous with mitral and tricuspid closure.

False

It corresponds with the QRS complex.

True

The mitral and tricuspid valves bulge back into the atria.

True

This closes the mitral and tricuspid valves.

False

It corresponds with the C wave; the A wave is due to atrial contraction which pre-
cedes the ﬁrst heart sound.

86.

True

This increases the rate of impulse generation and hence heart rate.

True

The increase in myocardial metabolism generates vasodilator metabolites.

True

Rapid spread of excitation in the ventricles results in more forceful contractions
as the ventricular ﬁbres are activated nearly simultaneously.

True

This enhances the force of contraction at any given ﬁlling pressure.

True

Due to the increased force of contraction.

87.

False

It is low because the capillary bed has a large total cross-sectional area.

True

The venous bed has a smaller total cross-sectional area than the venular bed.

True

There is a brief period of retrograde flow as the aortic valve closes.

True

Axial flow occurs in large vessels; near the walls, flow velocity is zero.

False

It rises due to the compensatory increase in cardiac output.

88.

True

As seen in the Frank–Starling left ventricular function curve.

False

High K

⫹

levels decrease cardiac contractility.

False

Calcium channel blockers decrease cardiac contractility.

True

Due to increased sympathetic drive to the ventricles and increased venous return.

True

Initially by increased ventricular ﬁlling: later by ventricular hypertrophy.

89.

True

Hence no blood leaves the ventricles.

False

Pressure in the aorta falls as run-off of blood to the tissues continues.

False

It rises as ventricular pressure causes the AV valves to bulge into the atria.

True

The blood vessels are squeezed by the contracting myocardium.

False

The greater force of contraction in the left ventricle gives a greater rate of rise of
pressure.

90.

False

The electrical event precedes the mechanical event.

True

This electrical event corresponds with ventricular relaxation.

False

It corresponds to the interval between atrial and ventricular depolarization due
to delay of the impulse in the AV bundle.

True

R indicates the beginning, and T the end, of the ventricular action potential.

True

Due to the heart rate changes associated with respiratory sinus arrhythmia.

91.

True

The output from the left and right ventricle is the same.

True

It depends on what happens to stroke volume.

True

Lying down normally increases the ﬁlling pressure of the heart.

True

To meet the needs of increased metabolism and increased skin blood flow.

False

The output does increase due to changes in the ﬁlling pressure, level of circulat-
ing hormones, etc.

MCQ

Cardiovascular system – questions

Questions 92–97

92. Arterioles

Have a smaller wall:lumen ratio than have arteries.

Play a major role in regulating arterial blood pressure.

Play a major role in regulating local blood flow.

Offer more resistance to flow than capillaries.

Have a larger total cross-sectional area than do the capillaries.

93. The Purkinje tissue cells in the heart

Conduct impulses faster than some neurones.

Are larger than ventricular myocardial cells.

Lead to contraction of the base before the apex of the heart.

Are responsible for the short duration of the QRS complex.

Are responsible for the conﬁguration of the QRS complex.

94. In the brachial artery

Pulse waves travel at the same velocity as blood.

Pulse pressure falls with decreasing elasticity of the wall.

Pressure rises markedly when the artery is occluded distally.

Pressure falls when the arm is raised above head level.

Pulse pressures have a smaller amplitude than aortic pulse pressures.

95. The tendency for blood flow to be turbulent increases when there is a

decrease in blood

Vessel diameter.

Density.

Flow velocity.

Viscosity.

Haemoglobin level.

96. Arterioles offer more resistance to flow than other vessels since they have

Thicker muscular walls.

Richer sympathetic innervation.

Smaller internal diameters.

A smaller total cross-sectional area.

A greater pressure drop along their length.

97. In the denervated heart, left ventricular stroke work increases when

The end-diastolic length of the ventricular ﬁbres increases.

Peripheral resistance rises.

Blood volume falls.

Right ventricular output increases.

The veins constrict.

MCQ

Cardiovascular system – answers

Answers

92.

False

In arterioles the ratio is much greater, at about 1:1.

True

They provide most of the peripheral resistance.

True

Local flow varies directly with the fourth power of their radii.

True

The drop in pressure across arterioles is greater than that across capillaries.

False

It is smaller, so blood flow velocity is higher in arterioles.

93.

True

They conduct at around 4 metres/second. Small diameter nerve ﬁbres conduct
impulses at about 1 metre per second.

True

This facilitates rapid conduction.

False

Purkinje ﬁbres travel to the apex before proceeding to the base of the heart.

True

They spread depolarization rapidly over the entire ventricular myocardium.

True

Damage to the cells (as in bundle-branch block) changes the pattern of spread of
ventricular depolarization, and hence the shape of the QRS complex.

94.

False

Pulse waves travel at about ten times the blood velocity.

False

It rises; arterial elasticity normally damps the pulse pressure.

False

Blood flows off rapidly via collaterals so that little pressure change occurs.

True

By the hydrostatic equivalent of the column of blood between it and the heart.

False

Brachial arterial pulse pressures are greater due to the superimposition of waves
reflected from the end of the arterial tree.

95.

False

The tendency is directly proportional to vessel diameter.

False

The tendency is directly proportional to fluid density.

False

The tendency is directly proportional to velocity.

True

The tendency is inversely proportional to viscosity.

True

In anaemia, the increase in velocity and decrease in viscosity of blood in the
hyperdynamic circulation promote turbulence; bruits may be heard over periph-
eral arteries.

96.

False

Wall thickness is not a factor determining resistance.

False

But it suggests that the resistance they offer may be varied by change in nerve
activity.

False

Capillaries have even smaller internal diameters.

False

The aorta has a much smaller total cross-sectional area.

True

The pressure drop across the arteriolar bed is larger than in other beds indicating
that arterioles are responsible for most of the circulation’s vascular resistance.

97.

True

As stated in the Frank–Starling Law.

True

This impedes ventricular outflow, thus increasing end-diastolic ﬁbre length.

False

This reduces cardiac ﬁlling pressure and hence end-diastolic ﬁbre length.

True

This tends to increase left ventricular ﬁlling pressure and end-diastolic ﬁbre
length.

True

This also raises cardiac ﬁlling pressure.

MCQ

Cardiovascular system – questions

Questions 98–103

98. With increasing distance from the heart, arterial

Walls contain relatively more smooth muscle than elastic tissue.

Flow has a greater tendency to be turbulent.

Mean pressure tends to rise slightly.

Pulse pressure tends to increase slightly.

falls appreciably.

99. In the estimation of cardiac output by an indicator dilution technique, the

Indicator must mix evenly with the entire blood volume.

Primary dilution curve may be followed by a secondary rise in indicator concentration.

Duration of the dilution curve shortens as cardiac output rises.

Mean indicator concentration under the curve increases as cardiac output rises.

Injection and monitoring devices may be placed in the pulmonary artery.

100. In the estimation of cardiac output using the Fick principle

Pulmonary blood flow is measured.

The P

of arterial and mixed venous blood are measured.

Oxygen uptake is estimated from alveolar P

measurements.

Pulmonary arterial blood is sampled to measure the oxygen in mixed venous blood.

Pulmonary venous blood is sampled to measure the oxygen in arterial blood.

101. Intravenous infusions of adrenaline and noradrenaline have similar

effects on

Skeletal muscle blood flow.

Renal blood flow.

Skin blood flow.

Diastolic arterial pressure.

Heart rate.

102. When the heart suddenly stops beating (cardiac asystole)

The physical signs are similar to those of ventricular ﬁbrillation.

Consciousness is lost after 1–2 minutes.

Cardiac compression should be applied at a rate of 10–15 per minute.

Artiﬁcial ventilation of the lungs should be given.

Electric shocks across the thorax should be applied.

103. Vasovagal fainting or syncope

Causes loss of consciousness.

Is associated with tachycardia.

Is associated with skeletal muscle vasodilation.

Is more likely to occur when standing than when lying down.

Is more likely to occur in a cold than in a hot environment.

MCQ

Cardiovascular system – answers

Answers

98.

True

The relative amount of smooth muscle increases but that of elastic tissue falls.

False

With the decreasing vessel diameter and flow velocity, the tendency decreases.

False

It falls slightly; blood will only flow down a pressure gradient.

True

Distal arterial pulse pressure is increased by the superimposition of waves
reflected back from the end of the arterial tree.

False

Blood cannot release its oxygen until it reaches the exchange vessels.

99.

False

Complete mixing with the blood is required for estimation of blood volume.

True

The secondary peak is due to recirculation of indicator.

True

Due to the more rapid passage of indicator past the sampling site.

False

It falls as the indicator is diluted in a bigger volume.

True

Pulmonary artery blood flow equals cardiac output.

100.

True

Pulmonary blood flow

⫽right ventricular output⫽cardiac output.

False

The O

content of arterial and mixed venous blood are measured.

False

To measure O

consumption, the subject breathes from a spirometer ﬁlled with

oxygen with a CO

absorber in the circuit; an open circuit method may also be

used.

True

The pulmonary artery is relatively easy to catheterize and the venous blood it
contains is thoroughly mixed.

False

Pulmonary veins are difﬁcult to catheterize. Blood from any artery may be used
since the O

content of peripheral arterial blood is the same as that in the pulmo-

nary vein.

101.

False

Adrenaline increases, and noradrenaline reduces skeletal muscle blood flow.

True

Both decrease renal blood flow.

True

Both cause cutaneous vasoconstriction.

False

Noradrenaline raises diastolic pressure; adrenaline lowers it.

False

Adrenaline increases heart rate; noradrenaline raises mean arterial pressure and
causes reflex cardiac slowing.

102.

True

In both cases there is no useful cardiac output.

False

Consciousness is lost within about ﬁve seconds.

False

60–80 compressions/minute are needed to maintain flow to the brain.

True

This is needed to maintain oxygenation of the brain.

False

This treatment (applied with a deﬁbrillator) is given for ventricular ﬁbrillation.

103.

True

Due to cerebral ischaemia caused by the abrupt fall in arterial pressure.

False

Increased vagal activity slows the heart and reduces cardiac output.

True

This vasodilation reduces peripheral resistance.

True

Because of gravity, pressure in cerebral arteries is lower when standing than
when lying down.

False

The skin vasoconstriction in cold environments raises peripheral resistance.

MCQ

Cardiovascular system – questions

Questions 104–109

104. Systemic hypertension may be caused by

Hypoxia due to chronic respiratory failure.

Excessive secretion of aldosterone.

Excessive secretion of adrenocorticotrophic hormone (ACTH).

Myocardial thickening (hypertrophy) of the left ventricle.

The rapid cardiac action of ventricular fibrillation.

105. Peripheral differs from central circulatory failure in that

Hypovolaemia is unusual.

It leads to underperfusion of the tissues.

Cardiac output is usually normal.

Central venous pressure is low.

Ventricular function is usually normal.

106. In atrial fibrillation

The electrocardiogram shows no evidence of atrial activity.

Ventricular rate is lower than atrial rate.

Respiratory sinus arrhythmia can usually be seen.

The ventricular rate is irregular.

The QRS complexes have an abnormal conﬁguration.

107. Severe systemic hypertension may result in

An increase in the number of myocardial cells in the left ventricle.

Increased QRS voltage in certain leads.

Increased coronary blood flow.

Pulmonary oedema.

Impaired vision.

108. Auscultation of the heart can provide evidence of

The direction of turbulent flow causing a murmur.

Aortic stenosis, if there is a loud pre-systolic murmur in the aortic valve area.

Mitral incompetence, if a systolic murmur is heard in the axilla.

Ventricular septal defect, if a loud diastolic murmur is heard.

Mitral stenosis, if an early diastolic and pre-systolic murmurs are heard.

109. The electrocardiogram shows

Irregular P waves in atrial flutter.

Regular QRS complexes in atrial ﬁbrillation.

Regular QRS complexes in complete heart block.

High voltage R waves over the right ventricle in right ventricular hypertrophy.

An irregular saw-tooth appearance in ventricular ﬁbrillation.

MCQ

Cardiovascular system – answers

Answers

104.

False

This constricts blood vessels in the lungs causing pulmonary hypertension but
dilates systemic vessels.

True

Salt and water retention by the kidneys expands ECF and hence blood volume
and cardiac output.

True

The resulting secretion of cortisol also causes salt and water retention.

False

This is a consequence of hypertension, not a cause.

False

This ineffective pumping in ventricular ﬁbrillation causes severe hypotension.

105.

False

Hypovolaemia due to severe haemorrhage is a common cause of peripheral cir-
culatory failure; blood volume may be normal in central circulatory failure.

False

Both types of failure lead to underperfusion of the tissues.

False

It is usually reduced in both types of failure.

True

It is usually raised in central circulatory failure.

True

Reduced ventricular function is the cause of central circulatory failure.

106.

False

Small rapid waves indicate the atrial ﬁbrillation.

True

Atrial rate is higher than ventricular rate as some impulses are ﬁltered out by the
atrioventricular node.

False

Sinus arrhythmia indicates normal sinus rhythm.

True

Due to the irregularity of the impulses passing through the AV node.

False

QRS complexes are normal since the pattern of ventricular depolarization is
normal.

107.

False

The cells increase in size (hypertrophy), not in number (hyperplasia).

True

Due to the left ventricular hypertrophy.

True

Due to increased left ventricular work.

True

Due to left ventricular failure.

True

Due to damage to retinal blood vessels.

108.

True

The direction in which the murmur is conducted indicates the direction of flow.

False

The characteristic murmur is a systolic murmur conducted to the neck vessels.

True

This is the direction of flow of the regurgitant blood.

False

The murmur occurs during ventricular contraction and is therefore systolic.

True

Mitral flow is greatest in early diastole but rises again during atrial systole.

109.

False

In atrial flutter, P waves have a high but regular frequency (about 300/minute).

False

Ventricular beats are irregular in rate and strength since impulses pass through
the AV node in a random fashion.

True

The beats generated by ventricular pacemakers have slow but regular frequency.

True

The increased muscle bulk generates enhanced voltages during depolarization.

True

Due to chaotic electrical activity in the ventricles.

MCQ

Cardiovascular system – questions

Questions 110–115

110. The jugular venous

Pulse is not visible in normal healthy people.

Pulse has greater amplitude in patients with tricuspid incompetence.

Pulse can vary widely in amplitude in patients with complete heart block.

Pressure is raised in patients with right ventricular failure.

Pressure is commonly raised in patients with mediastinal tumours.

111. In heart failure

The resting cardiac output may be higher than normal.

The arteriovenous oxygen difference during exercise is less than in normal people.

There is sodium retention.

Oedema occurs in dependent parts of the body.

Pulmonary oedema occurs when pulmonary capillary pressure doubles.

112. Respiratory failure (low arterial P

; raised arterial P

CO2

) leads to

Raised pulmonary artery pressure (pulmonary hypertension).

Right ventricular failure.

Low voltage P waves in the electrocardiogram.

Decreased cerebral blood flow.

Warm hands and feet.

113. Pain due to poor coronary blood flow (angina) may be relieved by

Cutting the sympathetic nerve trunks supplying the heart.

Correcting anaemia if present.

Providing the patient with a cold environment.

␤-adrenoceptor stimulating drugs.

Drugs causing peripheral vasodilation.

114. Narrowing of the lumen of major arteries supplying the leg is associated

with

Pain in the calf during exercise which is relieved by rest.

Growth of collateral vessels.

Reduction in the duration of reactive hyperaemias in the calf.

Delayed healing of cuts in leg skin.

Reduced arterial pulse amplitude at the ankle.

115. Arterial pulse contours that have

Sharp peaks indicate rapid left ventricular ejection.

Greatly increased pulse pressures are seen in patients with mitral incompetence.

Slowly rising systolic phases are seen in patients with aortic stenosis.

Varying beat-to-beat amplitude is seen in patients with atrial ﬁbrillation.

Rapid run-offs and low diastolic pressure suggest high peripheral resistance.

MCQ

Cardiovascular system – answers

Answers

110.

False

It can be seen in healthy people when they lie almost flat.

True

Systolic regurgitation of right ventricular blood can cause giant waves.

True

Periodic giant waves are seen when atrial and ventricular systoles coincide.

True

This is an important sign in right ventricular failure; venous pulsation is present.

True

The jugular veins are distended due to venous obstruction but there is little or no
pulsation.

111.

True

In high output failures; however, the ability to raise cardiac output in exercise is
impaired in all types of failure.

False

With inadequate output, desaturation of blood in the tissues increases.

True

This increases extracellular fluid and hence blood volume.

True

The back pressure in veins raises capillary hydrostatic pressure and results in
oedema in dependent parts where venous pressure is already raised due to grav-
ity.

False

When pulmonary capillary pressure (about 5 mmHg) doubles, it is still less than
plasma oncotic pressure (25 mmHg) so fluid does not accumulate in the alveoli.

112.

True

Hypoxia causes generalized pulmonary vasoconstriction.

True

Pulmonary hypertension can lead to right ventricular failure (‘cor pulmonale’).

False

Atrial hypertrophy in cor pulmonale results in prominent P waves.

False

dilates cerebral blood vessels.

True

is a vasodilator and ‘cor pulmonale’ is a ‘high output’ failure.

113.

True

Pain sensory ﬁbres from the heart travel with the sympathetic nerves.

True

In anaemia, the capacity of the blood to deliver oxygen is decreased but cardiac
work increases due to the rise in cardiac output.

False

Cold vasoconstriction raises arterial pressure and so increases myocardial work.

False

These increase heart rate and force and so increase myocardial work

True

By reducing arterial pressure, vasodilator drugs such as nitrates reduce myocar-
dial work.

114.

True

This is ‘intermittent claudication’; pain metabolites accumulate in muscle during
exercise in ischaemic limbs and stimulate local pain receptors.

True

When the major arteries are obstructed, collateral vessels open up to help main-
tain blood flow to the ischaemic tissues.

False

Though the hyperaemias have smaller peak values, their durations are longer.

True

Cuts and ulcers are slow to heal because the supply of nutrients is impaired.

True

Pulses may be absent with severe narrowing.

115.

True

As seen in strenuous exercise.

False

This is typical of aortic incompetence.

True

Due to slow expulsion of blood from the ventricle past the stenosed valve.

True

The variable ﬁlling of the ventricle results in variable stroke output.

False

They suggest a low peripheral resistance.

MCQ

Cardiovascular system – questions

Questions 116–120

116. Murmurs (or bruits) may be detected by auscultation over

Vessels in which there is turbulence.

Large arteries in healthy adults.

Dilations (aneurysms) in arteries.

Constrictions (stenoses) in arteries.

The heart in healthy young adults in early diastole.

117. Factors ensuring that ventricular muscle has an adequate oxygen supply

include the

Good functional anastomoses that exist between adjacent coronary arteries.

Structural arrangements that prevent vascular compression during systole.

High oxygen extraction rate from blood circulating through the myocardium.

Sympathetic vasodilator nerve supply to ventricular muscle.

Fall in coronary vascular resistance during exercise.

118. When the AV bundle is completely interrupted, as in complete heart

block, the

Atrial beat becomes irregular.

PR interval shows beat-to-beat variability.

Ventricular ﬁlling shows beat-to-beat variability.

QRS complex shows beat-to-beat variability.

Ventricular rate falls below 50 beats/minute.

119. Aortic valve incompetence may cause

Increase in arterial pulse pressure.

Systolic murmurs in the aortic valve area.

Hypertrophy of left ventricular muscle.

Decreased myocardial blood flow.

Left ventricular failure.

120. Ventricular extrasystoles

Are usually associated with a normal QRS complex.

From the same focus have similar QRS complexes.

Usually occur following a compensatory pause.

May fail to produce a pulse at the wrist.

Indicate serious heart disease.

MCQ

Cardiovascular system – answers

Answers

116.

True

Turbulent vibrations generate sound waves.

False

Flow is laminar rather than turbulent in normal large arteries.

True

Turbulence is set up as blood flows into the dilated segment.

True

Turbulence is set up as blood squirts through the constricted segment.

True

Rapid ventricular ﬁlling in early diastole can cause turbulence in healthy young
adults and generate a sound (the third heart sound).

117.

False

Coronary arteries are functional ‘end arteries’ and have few anastomotic connec-
tions; sudden occlusion of an artery usually leads to local muscle death.

False

Coronary vessels are compressed by the contracting myocardium in systole.

True

The extraction rate is about 75 per cent.

False

Reflex vasodilatation is not important in regulating coronary blood flow.

True

The rise in metabolic activity in the exercising heart provides the vasodilator
metabolites which adapt coronary flow to supply myocardial oxygen needs.

118.

False

The atria continue to beat regularly at normal sinus rate.

True

In complete block, atria and ventricles beat independently at different rates.

True

Due to loss of the normal sequence of the atrial and ventricular contractions.

False

There is usually a single ventricular pacemaker giving an abnormal but regular
QRS complex.

True

The ventricular intrinsic rate of beating is 30–40/minute.

119.

True

Diastolic pressure is abnormally low due to regurgitation of aortic blood into the
left ventricle in diastole.

False

Blood regurgitating in diastole causes diastolic turbulence.

True

The greater stroke volume needed to compensate for regurgitating blood increases
ventricular workload.

False

Flow increases as ventricular work increases.

True

A persistent increase in ventricular workload can lead to ventricular failure.

120.

False

Extrasystoles are associated with a prolonged abnormal QRS complex; the
impulse pathway from the ectopic focus over the myocardium is abnormal and
slow.

True

If the focus is the same, the pathway for ventricular excitation will be the same.

False

They are followed by a compensatory pause; the next normal beat may reach the
ventricles when they are refractory – a beat is lost.

True

If they occur early in diastole, poor ventricular ﬁlling results in weak contrac-
tions and small pulses.

False

They occur occasionally in many normal hearts.

MCQ

Cardiovascular system – questions

Questions 121–126

121. Pulmonary embolism (blood clots impacting in lung blood vessels)

usually decreases

Pulmonary vascular resistance.

Left atrial pressure.

Right atrial pressure.

Ventilation to perfusion ratios in the affected lung.

in pulmonary venous blood.

122. Hardening of the arterial walls tends to raise

Arterial compliance.

Systolic arterial pressure.

Diastolic arterial pressure.

Peripheral resistance.

Arterial pulse wave velocity.

123. The ‘A’ wave of venous pulsation in the neck is

Caused by atrial systole.

Seen just after the carotid artery pulse.

Exaggerated in atrial ﬁbrillation.

Exaggerated in tricuspid stenosis.

Exaggerated periodically in complete heart block.

124. Left ventricular failure tends to cause an increase in

Left atrial pressure.

Left ventricular ejection fraction.

Pulmonary capillary pressure.

Lung compliance.

Pulmonary oedema when the patient stands up.

125. In otherwise healthy people, local tissue death follows obstruction of

An internal carotid artery.

A renal artery.

A femoral artery.

A retinal artery.

The hepatic portal vein.

126. In the measurement of forearm blood flow by venous occlusion

plethysmography

A continuous record is made of forearm volume.

A collecting cuff is applied to the wrist.

It is assumed that venous outflow is arrested by the collecting cuff during measurement.

The collecting cuff pressure should be greater than diastolic but less than systolic arte-
rial pressure.

The forearm must be kept below heart level during the measurements.

MCQ

Cardiovascular system – answers

Answers

121.

False

Vascular obstruction tends to increase pulmonary vascular resistance and cause
pulmonary hypertension.

True

Due to the fall in pulmonary blood flow, atrial pressure tends to fall.

False

The obstruction tends to dam back blood in the right heart.

False

It rises since pulmonary capillary perfusion falls.

False

Blood that traverses pulmonary capillaries is adequately oxygenated; cyanosis in
patients with pulmonary embolism is usually peripheral cyanosis due to low car-
diac output.

122.

False

Compliance, the change of arterial volume per unit pressure change, decreases.

True

Systolic ejection causes greater pressure rise when arteries are less distensible.

False

Poor elastic recoil in diastole allows diastolic pressure to fall further.

False

Stiffness of the wall is not a factor determining vascular resistance.

True

Vibrations travel faster in stiff than in lax structures.

123.

True

The pressure wave due to atrial contraction passes up freely into the neck.

False

Atrial systole precedes the ventricular systole that generates the carotid pulse.

False

It is absent – there is no effective atrial systole in atrial ﬁbrillation.

True

Right atrial contraction is more forceful to overcome valvular resistance.

True

If the atrial and ventricular systoles coincide, the A and C waves merge to give a
giant wave.

124.

True

Due to inadequate emptying of the left ventricle in systole.

False

Stroke volume falls; end-diastolic volume rises.

True

The rise may cause pulmonary oedema if pressure exceeds the colloid osmotic
pressure of the plasma proteins.

False

It falls; congestion of pulmonary vessels with blood makes the lungs stiffer.

False

The decrease in venous return on standing up may relieve pulmonary congestion
and hence dyspnoea.

125.

False

Flow through the circle of Willis normally maintains the viability of the tissue.

True

There is no signiﬁcant collateral circulation.

False

Normally there is adequate collateral circulation. However, if there is advanced
arterial disease, sudden obstruction may cause gangrene.

True

The collateral circulation is not good enough to prevent this.

False

The liver has a dual blood supply; the hepatic artery flow can maintain viability.

126.

True

Plethysmography means volume measurement.

False

It is applied to the upper arm.

True

When this is the case, the volume increase equals arterial inflow.

False

It must be below diastolic so as not to interfere with arterial inflow.

False

Below heart level, the veins ﬁll with blood and are unable to accommodate more
during venous occlusion; the forearm must be above heart level.

MCQ

CARDIOVASCULAR SYSTEM

EMQs

Questions 127–138

EMQ Question 127

For each of the clinical descriptions (A–E) select the most appropriate options from the follow-
ing list of circulatory changes.

1. Increased cerebral vascular resistance. 2. Decreased cerebral vascular resistance.
3. Increased coronary resistance.

4. Decreased coronary resistance.

5. Increased splanchnic resistance.

6. Decreased splanchnic resistance.

7. Increased vascular resistance in skin.

8. Decreased vascular resistance in skin.

9. Increased renal vascular resistance.

10. Decreased renal vascular resistance.

11. Increased regional perfusion pressure. 12. Decreased regional perfusion pressure.

A patient with a head injury receives artiﬁcial hyperventilation to reduce cerebral
oedema.

It has been found that gastric mucosal intracellular acidosis as an indicator of local
stagnant hypoxia is useful in assessing splanchnic blood flow in peripheral circulatory
failure.

Patients with myocardial infarction show electrocardiological improvement after treat-
ment to convert plasminogen into plasmin within six hours of heart attack.

A patient suffering from chronic respiratory failure with carbon dioxide retention has
headaches and is found to have papilloedema.

An elderly patient suffering from diarrhoea and vomiting for several days cannot sit or
stand without developing loss of consciousness (syncope).

EMQ

Cardiovascular system – answers

Answers for 127

Option 1

Increased cerebral vascular resistance. Hyperventilation leads to constriction

of cerebral vessels due to washout of carbon dioxide from the body. This leads to
decreased cerebral capillary pressure and a reduction in cerebral interstitial fluid volume,
thereby reducing the oedema generated by head injury.

Option 5

Increased splanchnic resistance. In circulatory failure, blood pressure is sup-

ported by increased peripheral vascular resistance induced by the baroreceptor reflex, par-
ticularly in the splanchnic circulation. Splanchnic vasoconstriction occurs early in the
condition. The resultant stagnant hypoxia in the alimentary mucosa is thus a sensitive
index of the early stages of circulatory failure before more severe effects such as hypo-
tension are obvious.

Option 4

Decreased coronary resistance. Myocardial infarction results from complete

or almost complete cessation of perfusion of a region of cardiac muscle due to blocking,
often by thrombosis, of a coronary artery or arteries. This reduces flow by a massive
increase in resistance and a considerable mass of myocardium is threatened by stagnant
hypoxia due to poor flow (ischaemia). Activation of circulating plasminogen to plasmin
allows breakdown of blood clot (thrombolysis) and decreases regional coronary resistance
to a level which allows recovery of ischaemic areas.

Option 2

Decreased cerebral vascular resistance. Carbon dioxide is an important

determinant of cerebral blood flow by its local vasodilator action (in underperfused areas
carbon dioxide accumulates and this leads to vasodilation and restoration of normal per-
fusion). When there is a raised level of carbon dioxide in arterial blood there is general-
ized cerebral vasodilation and this leads to increased formation of tissue fluid (oedema).
The resultant increased intracranial pressure leads to headaches and papilloedema, imitat-
ing the effects of an intracranial tumour or abscess.

Option 12

Decreased regional perfusion pressure. With persistent diarrhoea and vomit-

ing, extracellular fluid volume can fall severely. The reduced plasma volume leads to
hypotension, especially in the elderly whose compensatory mechanisms are blunted.
Sitting and standing trap circulating fluid in the feet causing a severe fall in arterial blood
pressure. This decreases cerebral perfusion pressure to a point at which a local decrease in
vascular resistance cannot compensate and loss of consciousness (syncope) occurs from
cerebral ischaemia (inadequate blood flow).

EMQ

Cardiovascular system – questions

EMQ Question 128

For each of the clinical scenarios A–E, select the most appropriate option from the cardiovas-
cular parameters listed below.

Heart rate (per min)

Stroke volume (ml)

Pulse pressure (mmHg)

120

180

110

140

100

240

A 30-year-old man has been admitted to hospital for minor elective surgery. He is a
long-distance runner of national standard. His cardiac shadow is enlarged on chest X-
ray and there is concern about his very slow pulse.

A 50-year-old woman has been admitted to hospital for thyroid surgery and is found to
have signs of severe uncontrolled hyperthyroidism. Her peripheries are warm and moist
and her pulse is rapid and bounding.

A 40-year-old woman trains regularly for physical ﬁtness but has been concerned
recently about chest discomfort, fearing coronary artery disease. She undertakes cardio-
logical assessment during progressive exercise on a treadmill and the results correspond
to the ﬁnal stage of severity, rarely reached by the patients assessed. At this stage her
systolic arterial pressure was 180 mmHg.

A 40-year-old woman reports recent episodes of threatened loss of consciousness during
exercise and such an episode occurs during treadmill testing in hospital.

A 70-year-old man has been admitted to hospital after he collapsed at home and found
he could not sit up without feeling he was about to faint. He suffers from epigastric
pain treated by a proton pump inhibitor and has recently noticed his bowel motions are
loose and very dark. On admission he is pale and sweating with cold peripheries and his
systolic arterial pressure is 80 mmHg even with the foot of the bed raised.

EMQ

Cardiovascular system – answers

Answers for 128

Option 4

These results are typical of a high level athlete – a normal resting cardiac

output of 5.6 litres per minute with a very slow pulse rate compensating for a huge rest-
ing stroke volume. Such people have relatively large powerful hearts which contrast dra-
matically with the large weak hearts of patients with cardiac failure, some of whom may
suffer from a pathologically slow heart rate which exacerbates their condition.

Option 5

Hyperthyroidism leads to a hyperdynamic circulation at rest – rapid strong

pulse associated with a high pulse pressure and an increased cardiac output (7 litres per
minute in her case). This is required for the increased metabolic rate due to the overactive
thyroid. The increased metabolic rate also generates excess heat, hence the sweating.

Option 3

This woman is typical of patients with chest pain not due to coronary artery

disease. In association with regular training she is very ﬁt and can exercise to the maxi-
mal level used in the treadmill cardiac stress test. At this stage she shows typical ﬁndings
of a cardiac output of about 20 litres per minute and arterial blood pressure 180/70 (high
systolic due to powerful ejection by the left ventricle and rapidly falling pressure due to
very low peripheral resistance). She has achieved the maximal predicted heart rate (220
minus age in years).

Option 6

Syncope or pre-syncope during exercise can be due to an abnormal ineffec-

tive rapid cardiac rhythm (tachycardia). As with the previous case the maximal expected
rate is 180 and a rate of 240 does not allow adequate ﬁlling for a useful stroke volume.
Such a low cardiac output (3.6 litres per minute) would lead to loss of consciousness
during mild to moderate exercise.

Option 2

This patient gives a history suggesting peptic ulcer treated by a drug which

raises gastric pH to relieve the pain. The history is strongly suggestive of chronic loss of
blood in the faeces (melaena). With an arterial blood pressure of 80/60 he cannot sustain
adequate cerebral blood flow in the upright posture. This is because of the reduced venous
return experienced by everyone in the upright position. Raising the foot of the bed max-
imizes venous return. He is suffering from peripheral circulatory failure due to severe
blood loss and blood transfusion is urgently indicated.

EMQ

Cardiovascular system – questions

EMQ Question 129

For each of the physiological characteristics A–E, select the most appropriate option from the
types of blood vessels listed below.

1. Veins.

2. Arteries.

3. Arterioles.

4. Venules.

5. Arteria-venous anastomoses.

The major source of peripheral resistance.

Are important in temperature regulation.

Their walls contain relatively more elastic tissue than other blood vessels.

Their valves prevent retrograde flow.

Have the greatest wall thickness to lumen ratio in blood vessels.

EMQ Question 130

For each of the valvular functions A–E, select the most appropriate option from the valves
listed below.

1. Mitral valve

2. Tricuspid valve.

3. Aortic valve.

4. Foramen ovale valve.

5. Pulmonary valve.

Preventing regurgitation of right ventricle inflow.

Preventing regurgitation of left ventricular outflow.

Preventing regurgitation of left ventricular inflow.

Preventing regurgitation of right ventricular outflow.

Preventing flow from the left to the right atrium after birth.

EMQ Question 131

For each of the physiological responses A–E, select the most appropriate option from the effec-
tor mechanisms listed below.

1. Vasodilator metabolites.

2. Autoregulatory responses.

3. Vasodilator nerves.

4. Vasoconstrictor nerves

5. Endothelium derived relaxing factor (EDRF).

Minimizing blood flow changes in response to changes in perfusion pressure.

Increasing local blood flow by a decrease in their activity.

Release of noradrenaline.

Baroreceptor reflex responses.

Reactive hyperaemia responses.

EMQ

Cardiovascular system – answers

Answers for 129

Option 3

Arterioles. Arterioles are the main source of peripheral resistance in the cir-

culation since the fall in blood pressure across arteriolar vessels is greater than in any
other vascular segment.

Option 5

Arterio-venous anastomoses. The AV anastomoses in the extremities such as

the ﬁngers and toes open up when body temperature rises and the resulting increase in
blood flow raises skin temperature so that there is greater heat loss from the skin.

Option 2

Arteries. The arteries, especially those near the heart, are highly elastic. This

tissue is stretched during systole and the energy so stored is fed back during diastole to
maintain the diastolic pressure. Thus the elastic tissue dampens the large pressure gra-
dients generated by the ventricles into the smaller pressure pulses seen in the arterial
system.

Option 1

Veins. These valves aid return of blood to the heart. When veins are com-

pressed by surrounding muscles or other organs, the valves do not allow retrograde flow
of blood, the blood in the veins is forced forward towards the heart.

Option 3

Arterioles. The walls of arterioles are relatively thick relative to their lumen

because of the comparatively high smooth muscle component. This muscle is controlled
by vasoactive substances and vasomotor nerves to regulate local blood flow.

Answers for 130

Option 2

Tricuspid valve. This valve closes when right ventricular pressure exceeds

right atrial pressure and so prevents regurgitation of blood into the atrium when the right
ventricle contracts.

Option 3

This valve, situated in the mouth of the aorta, closes during diastole when

aortic pressure exceeds left ventricular pressure. Incompetence of this valve allows reflux
of blood from the aorta back into the ventricle and increases the work of the heart to
maintain the same cardiac output.

Option 1

Mitral valve. This valve closes when left ventricular pressure exceeds left

atrial pressure and so prevents regurgitation of blood into the atria when the ventricle
contracts. When disease results in valve incompetence, a systolic murmur may be heard
over the heart.

Option 5

Pulmonary valve. This valve, situated in the mouth of the pulmonary artery,

closes during diastole when pulmonary artery pressure exceeds right ventricular pressure.

Option 4

Foramen ovale valve. This valve closes the foramen ovale in the inter-atrial

septum when return of blood in the pulmonary veins raises left atrial pressure above right
atrial pressure.

Answers for 131

Option 2

Autoregulatory responses. When the perfusion pressure rises, the stretching

of the smooth muscle in the walls of blood vessels causes it to contract and so minimize
the increase in blood flow that would otherwise occur.

Option 4

Vasoconstrictor nerves. These sympathetic nerves are normally active to

exert a steady vasoconstrictor ‘tone’. When their activity is decreased, the smooth muscle
in the walls of the blood vessels relaxes to cause an increase in local blood flow.

Option 4

Vasoconstrictor nerves. The neurotransmitter for sympathetic vasoconstric-

tor nerves is noradrenaline

Option 4

Vasoconstrictor nerves. When arterial pressure falls, it is countered by a

reflex increase in vasoconstrictor tone that raises peripheral resistance.

Option 1

Vasodilator metabolites. The increase in local blood flow after circulatory

arrest (reactive hyperaemia) is due to the accumulation of products of metabolism caus-
ing vasodilation during the arrest period.

EMQ

Cardiovascular system – questions

EMQ Question 132

For each of the reflex systems A–E, select the most appropriate option from the types of recep-
tors listed below.

1. Arterial stretch receptors.

2. Arterial chemoreceptors.

3. Pulmonary stretch receptors.

4. Atrial stretch receptors.

5. Coronary artery chemoreceptors.

The reflex regulation of blood pressure.

The reflex regulation of ventilation.

The reflex regulation of blood volume.

System causing reflex hypotension, bradycardia and apnoea.

The Hering–Breuer reflex.

EMQ Question 133

For each of the physiological characteristics A–E, select the most appropriate option from the
special circulations listed below.

1. Coronary blood flow.

2. Skeletal muscle blood flow.

3. Splanchnic blood flow.

4. Cerebral blood flow.

5. Skin blood flow.

Increases during sweating.

Greater during diastole than during systole.

Passes through a portal circulation.

Affected mainly by the P

level in the blood.

Increases during fainting.

EMQ Question 134

For each of the cardiac phenomena A–E, select the most appropriate option from the features
of the electrocardiogram listed below.

1. The T wave.

2. The P wave.

3. The P–R interval.

4. Depression of the ST segment.

5. A flat record.

Cardiac arrest.

Repolarization of the ventricles.

Inadequate blood flow to ventricular muscle.

The delay in impulse conduction in the AV node.

Spread of the cardiac impulse over the atria.

EMQ Question 135

For each of the physiological changes A–E, select the most appropriate option from the pos-
sible precipitating causes listed below.

1. Fainting.

2. Severe haemorrhage.

3. Severe exercise.

4. Late pregnancy.

5. Hypothermia.

6. Lying down.

A fall in the haematocrit.

A decrease in heart rate.

A decrease in oxygen consumption.

A reduction in venous capacity.

An increased right atrial pressure.

EMQ

Cardiovascular system – answers

Answers for 132

Option 1

Arterial stretch receptors. Stretch of these receptors by a rise in blood pres-

sure results in a reflex reduction in heart rate and vasoconstrictor tone to limit the rise in
pressure.

Option 2

Arterial chemoreceptors. A fall in P

or pH or a rise in P

stimulates the

arterial chemoreceptors to cause a reflex increase in pulmonary ventilation. The main
stimulation effect of CO

on breathing is via the respiratory centre in the medulla oblon-

gata but the stimulatory effect of hypoxia is via the arterial chemoreceptors only.

Option 4

Atrial stretch receptors. Stretch of atrial stretch receptors results in a fall in

blood pressure and an increase in urinary output.

Option 5

Coronary artery chemoreceptors. C ﬁbres close to the walls of coronary ves-

sels are stimulated by certain circulating substances such as serotonin and veratridine, to
cause hypotension, bradycardia and perhaps apnoea (the Bezold–Jarisch reflex).

Option 3

Pulmonary stretch receptors. When pulmonary stretch receptors are

stretched during inspiration, they send impulses to the brain via the vagus nerves that
inhibit the inspiratory centre in the medulla oblongata.

Answers for 133

Option 5

Skin blood flow. Skin blood flow increases during sweating due to an active

sympathetic cholinergic mechanism.

Option 1

Coronary blood flow. Coronary blood flow is decreased during systole

because of compression of the vessels by the contracting ventricular myocardium.

Option 3

Splanchnic blood flow. Splanchnic blood flow passes through two capillary

beds in one circuit of the circulation, ﬁrstly through the capillaries in the alimentary tract
and then through a portal capillary bed in the liver.

Option 4

Cerebral blood flow. Cerebral blood flow is little affected by cardiovascular

reflexes. However it is very sensitive to changes in the P

of the perfusing blood.

Option 2

Skeletal muscle blood flow. Vasodilatation in skeletal muscle during fainting

causes a large fall in peripheral resistance and is one of the factors leading to the fall in
arterial pressure that results in the faint.

Answers for 134

Option 5

A flat record. During asystole no ECG complexes can be detected.

Option 1

The T wave. The T wave marks the end of the ventricular depolarization that

gives rise to systole.

Option 4

Depression of the ST segment. Depression of the ST segment is a sign of

ischaemia during cardiac treadmill testing.

Option 3

The P–R interval. This delay allows the atria to contract before the ventri-

cles contract.

Option 2

The P wave. Abnormalities in the P waves indicate atrial dysfunction.

Answers for 135

Option 4

Late pregnancy. The relative increase in plasma volume in late pregnancy

results in a low haematocrit.

Option 1

Fainting. The vagal element of the vaso-vagal faint can cause severe brady-

cardia.

Option 5

Hypothermia. The decrease in the metabolic rate in hypothermia reduces

oxygen consumption.

Option 2

Severe haemorrhage. The intense reflex venoconstriction in severe haemor-

rhage may make it difﬁcult to insert catheters for introducing intravenous fluids.

Option 6

Lying down. Due to the increase in venous return to the heart.

EMQ

Cardiovascular system – questions

EMQ Question 136

For each of the features of the capillary circulation A–E, select the most appropriate option
from the possible locations and precipitating causes listed below.

1. In the brain.

2. In Vitamin C deﬁciency.

3. In exercising muscle.

4. After haemorrhage.

5. In the spleen.

High permeability.

Low permeability.

High fragility.

Net outflow of fluid.

Net inflow of fluid.

EMQ Question 137

For each of the functional characteristics of heart muscle A–E, select the most appropriate
option from the types of heart muscle listed below.

1. The sinoatrial node.

2. The Purkinje system.

3. The AV node.

4. Atrial muscle.

5. Ventricular muscle.

The fastest conduction rate in the heart.

The slowest conduction rate in the heart.

The fastest pacemaker in the heart.

Associated with the P wave of the electrocardiogram.

The longest action potentials.

EMQ Question 138

For each of the circulatory features A–E, select the most appropriate option from the special
circulations listed below.

1. Hypothalamic circulation.

2. Coronary circulation.

3. Pulmonary circulation.

4. Fetal circulation.

5. Cerebral circulation.

A low-pressure circulation.

A portal capillary system.

Functional end arteries.

A ductus arteriosus.

An elaborate anastomotic system.

EMQ

Cardiovascular system – answers

Answers for 136

Option 5

In the spleen. Splenic capillaries, because of the large slits between adjacent

endothelial cells, are freely permeable to most solutes.

Option 1

In the brain. Because of the ‘blood–brain barrier’, cerebral capillaries are

much less permeable than capillaries elsewhere in the body so that tissue fluid in the brain
differs in composition from that of plasma.

Option 2

In Vitamin C deﬁciency. Capillary (petechial) haemorrhages are a feature of

scurvy caused by Vitamin C deﬁciency.

Option 3

In exercising muscle. Because the arteriolar vasodilation raises capillary

pressure.

Option 4

After haemorrhage. Because arteriolar constriction decreased capillary pres-

sure.

Answers for 137

Option 2

The Purkinje system. The modiﬁed heart muscle ﬁbres in the Purkinje system

can conduct the impulse at about 8 metres/second.

Option 3

The AV node. The slow conduction of the impulse through the AV node

allows the atrial muscle to contract before ventricular contraction begins.

Option 1

The sinoatrial node. The sinoatrial node normally generates impulse faster

than any other cardiac pacemaker and so in responsible for the normal heart rate.

Option 4

Atrial muscle. The P wave results from the spread of excitation from the

sinoatrial node over the atria.

Option 5

The longest action potentials. Ventricular muscle action potentials are much

longer than those in atrial muscle.

Answers for 138

Option 3

Pulmonary circulation. Pressure in the pulmonary circuit is much lower than

that in the systemic circuit since it offers much less resistance to flow.

Option 1

Hypothalamic circulation. The capillary bed in the hypothalamus is con-

nected by blood vessels to a second capillary bed in the anterior pituitary gland. This
allows hormones secreted in the hypothalamus to be carried to the pituitary where they
lead to the release of certain pituitary gland hormones.

Option 2

Coronary circulation. Coronary arteries, though they are connected by anas-

tomotic vessels act as functional end arteries so that when one is blocked the ventricular
muscle served by that artery dies.

Option 4

Fetal circulation. During fetal life, blood returning from the placenta to the

right atrium bypasses the pulmonary circuit by (i) passing through the foramen ovale; and
(ii) being diverted from the proximal part of the pulmonary artery via the ductus arterio-
sus to the aorta.

Option 5

Cerebral circulation. The circle of Willis is a vascular arrangement at the

base of the brain into which all the main arteries to the brain connect so that if one artery
should block, the brain can still be supplied by the other arteries in this anastomotic
arrangement.

EMQ

RESPIRATORY SYSTEM

MCQs

Questions 139–144

139. In a person breathing normally at rest with an environmental tempera-

ture of 25°C, the partial pressure of

in alveolar air is about twice that in room air.

Water vapour in alveolar air is less than half the alveolar P

level.

Water vapour in alveolar air is greater than that in room air even at 100 per cent
humidity.

in expired air is greater than in alveolar air.

in mixed venous blood is greater than in alveolar air.

140. As blood passes through systemic capillaries

pH rises.

HCO

⫺

ions pass from red cells to plasma.

⫺

ion concentration in red cells falls.

Its oxygen dissociation curve shifts to the right.

Its ability to deliver oxygen to the tissues is enhanced.

141. The respiratory centre

Is in the hypothalamus.

Sends impulses to inspiratory muscles during quiet breathing.

Sends impulses to expiratory muscles during quiet breathing.

Is involved in the swallowing reflex.

Is involved in the vomiting reflex.

142. The carotid bodies

Are stretch receptors in the walls of the internal carotid arteries.

Have a blood flow per unit volume similar to that in the brain.

Are influenced more by blood P

than by its oxygen content.

Generate more afferent impulses when blood H

⫹

ion concentration rises.

And the aortic bodies are mainly responsible for the increased ventilation in hypoxia.

143. Pulmonary surfactant increases

The surface tension of the fluid lining alveolar walls.

Lung compliance.

In effectiveness as the lungs are inflated.

In amount when pulmonary blood flow is interrupted.

In amount in fetal lungs during the last month of pregnancy.

144. As people age, there is usually a decrease in their

Ratio of lung residual volume to vital capacity.

Percentage of vital capacity expelled in one second.

Lung volume level at which small airways start to close during expiration.

Lung elasticity.

Resting arterial blood P

MCQ

Respiratory system – answers

Answers

139.

False

Room air P

(0.2 mmHg; 0.03 kPa) is negligible compared with alveolar air P

(40 mmHg; 5.3 kPa).

False

Alveolar H

O vapour pressure at 37

C is 47 mmHg (6.3 kPa).

True

Alveolar air is saturated with water vapour at 37˚C. At 25˚C saturated vapour
pressure is 24 mmHg (3.2 kPa), about half that at 37˚C.

True

Expired air is alveolar air plus dead space air.

True

This is necessary for CO

excretion by diffusion.

140.

False

It falls, due largely to CO

uptake.

True

Incoming CO

is converted to HCO

⫺

(carbonic anhydrase in RBCs catalyses the

reaction CO

⫹H

⫽H

⫹

⫹HCO

⫺

; HCO

⫺

migrates out as its concentration rises.

False

It rises as Cl

⫺

moves in to replace departing HCO

⫺

in the ‘chloride shift’.

True

Due largely to the rise in blood P

True

Due to the shift of the oxygen dissociation curve.

141.

False

It is in the medulla oblongata.

True

Causing expansion of the thorax cage.

False

Expiration at rest is passive.

True

It is inhibited during swallowing so preventing aspiration of food.

True

Expiratory, including abdominal muscle contraction with the oesophagus relaxed
and the glottis closed helps expel gastric contents in vomiting.

142.

False

The stretch receptors in internal carotid arteries are carotid sinus baroreceptors;
the carotid bodies are separate structures nearby.

False

They have the greatest flow rate/unit volume yet described in the body.

True

They are not excited in anaemia where P

is normal but O

content is low.

True

Acidosis stimulates ventilation.

True

When carotid and aortic bodies are denervated, hypoxia depresses respiration.

143.

False

It decreases surface tension.

True

It permits the lungs to be more easily inflated.

False

The decreasing effect as lungs inflate helps prevent overinflation.

False

It decreases; this may lead to local collapse of the lung.

True

Premature babies may have breathing problems due to surfactant deﬁciency.

144.

False

Residual volume increases and vital capacity decreases.

True

This gradually falls with normal ageing.

False

The ‘closing volume’ increases with age.

True

This increases residual and closing volumes.

True

There is, however, little change in oxygen saturation.

MCQ

Respiratory system – questions

Questions 145–151

145. During inspiration

Intrapleural pressure is lowest at mid-inspiration.

Intrapulmonary pressure is lowest around mid-inspiration.

Intraoesophageal pressure is lowest at mid-inspiration.

The rate of air flow is greatest at end-inspiration.

The lung volume/intrapleural pressure relationship is the same as in expiration.

146. Carbon dioxide

Is carried as carboxyhaemoglobin on the haemoglobin molecule.

Uptake by the blood increases its oxygen-binding power.

Uptake by the blood leads to similar increases in H

⫹

and HCO

⫺

ion concentrations.

Stimulates ventilation when breathed at a concentration of 20 per cent.

Content is greater than oxygen content in arterial blood.

147. In normal lungs

The rate of alveolar ventilation at rest exceeds the rate of alveolar capillary perfusion.

The ventilation/perfusion (V/P) ratio exceeds 1.0 during maximal exercise.

The V/P ratio is higher at the apex than at the base of the lungs when a person is
standing.

Oxygen transfer can be explained by passive diffusion.

Dead space increases during inspiration.

148. Alveolar ventilation is increased by breathing

21 per cent O

and 79 per cent N

17 per cent O

and 83 per cent N

2 per cent CO

and 98 per cent O

10 per cent CO

and 90 per cent O

A gas mixture which raises arterial P

by 10 per cent.

149. Bronchial smooth muscle contracts in response to

Bronchial mucosal irritation.

Local beta adrenoceptor stimulation.

A fall in bronchial P

Inhalation of cold air.

Circulating noradrenaline.

150. In early inspiration there is a fall in

Intrapulmonary pressure.

Intrathoracic pressure.

Intra-abdominal pressure.

Dead space P

Pressure in the superior vena cava.

151. Compliance of the lungs is greater

When they are expanded above their normal tidal volume range.

In adults than in infants.

Than the compliance of the lungs and thorax together.

When they are ﬁlled with normal saline than when they are ﬁlled with air.

In standing than in recumbent subjects.

MCQ

Respiratory system – answers

Answers

145.

False

It is lowest at the end of inspiration.

True

After mid-inspiration, intrapulmonary pressure rises as air is drawn into the
lungs.

False

Its pattern is similar to that of intrapleural pressure.

False

It is greatest at mid-inspiration; it depends on the mouth:alveoli pressure gradient.

False

Volume changes lag behind pressure changes to give a hysteresis loop.

146.

False

It is carried as carbaminohaemoglobin; carboxyhaemoglobin is the combination
of haemoglobin with carbon monoxide.

False

It decreases as the oxygen dissociation curve is shifted to the right.

False

HCO

⫺

ions increase more; H

⫹

ions are largely buffered by haemoglobin.

False

Breathing 20 per cent CO

causes respiratory depression; stimulation of respira-

tion by CO

is maximal when breathed at concentrations of around 5 per cent.

True

content in arterial blood is about 500 ml/l; O

content is about 200 ml/l.

147.

False

Alveolar ventilation at rest is about 4 l/min; perfusion is about 5 l/min.

True

In maximal exercise, alveolar ventilation may rise to about 80 l/min whereas
alveolar perfusion (cardiac output) rises to about 25 l/min.

True

Perfusion decreases from base to apex; ventilation does also but to a lesser extent.

True

There is no evidence of O

secretion in the lungs.

True

The trachea and bronchi expand as the lungs expand.

148.

False

This is the normal composition of air.

False

The O

level must fall to around 15 per cent before breathing is stimulated.

True

The stimulating effect of high P

is little affected by high P

levels.

False

This level of carbon dioxide depresses breathing.

True

This is enough to double the volume breathed per minute.

149.

True

Via a reflex with a parasympathetic efferent pathway.

False

This leads to relaxation.

True

This tends to limit local overventilation.

True

This is minimized normally by the warming of air in the upper airways.

False

This causes relaxation via beta receptors.

150.

True

This creates a pressure gradient between mouth and lungs.

True

Due to an increase in the dimensions of the thoracic cage.

False

It rises due to descent of the diaphragm.

False

It rises as inspired air replaces alveolar air.

True

It falls as intrathoracic pressure falls.

151.

False

Compliance is maximal in the tidal volume range.

True

Compliance is extremely small in infants.

True

It is nearly twice as great.

True

There are no surface tension forces to overcome in fluid-ﬁlled lungs.

True

Lungs are less stiff when their blood content falls.

MCQ

Respiratory system – questions

Questions 152–158

152. At a high altitude where atmospheric pressure is halved, there is an

increase in

Pulmonary ventilation.

Alveolar H

O vapour pressure.

Arterial P

Arterial pH.

Cerebral blood flow.

153. During inspiration

Venous return to the heart is increased.

More energy is expended than during expiration.

Lung expansion is assisted by surface tension forces in the alveoli.

Lung expansion begins when intrapleural pressure falls below atmospheric.

Lung expansion ends when intrapulmonary pressure falls to atmospheric.

154. The residual volume is

The gas remaining in the lungs at the end of a full expiration.

Greater on average in men than in women.

3–4 litres on average in young adults.

Measured directly using a spirometer.

Smaller in old than in young people.

155. A rise in arterial P

CO2

leads to an increase in

Ventilation due to stimulation of peripheral chemoreceptors.

Ventilation due to stimulation of central chemoreceptors.

Arterial pressure.

Cerebral blood flow.

The plasma bicarbonate level.

156. Ventilation is increased during

Periods when cerebrospinal fluid pH is reduced.

Chronic renal failure.

Periods when plasma bicarbonate level is raised.

Deep sleep.

Exercise because of the ensuing fall in arterial P

157. Voluntarily hyperventilation increases the

Negative charge on the plasma proteins.

Level of ionized calcium in blood.

Alveolar P

three-fold when ventilation is increased three-fold.

Arterial blood oxygen saturation by 10–15 per cent when ventilation is increased by
10–15 per cent.

The renal excretion of bicarbonate.

158. If the carotid and aortic chemoreceptors are denervated

Increasing alveolar P

by 25 per cent fails to stimulate ventilation.

Halving the alveolar P

fails to stimulate ventilation.

The resting ventilation rate is depressed by more than 40 per cent.

Ventilation does not increase during exercise.

The ability to adapt to life at high altitude is impaired.

MCQ

Respiratory system – answers

Answers

152.

True

Due to stimulation of chemoreceptors by oxygen lack.

False

This remains at the saturated pressure at body temperature.

False

The fall in arterial P

stimulates the carotid bodies to increase ventilation.

True

Hyperventilation causes respiratory alkalosis.

False

The fall in P

causes cerebral vasoconstriction.

153.

True

By decreasing intrathoracic venous pressure.

True

Expiration is assisted by the elastic recoil of the lungs and thoracic cage.

False

Surface tension is a force to be overcome in inspiration.

False

Expansion begins when intrapulmonary pressure falls below atmospheric.

True

There is no pressure gradient at this point to drive air.

154.

True

This is its deﬁnition.

True

Men, on average, have bigger thoracic cages than women.

False

It is around 1–1.5 litres

False

Residual air cannot be exhaled; it is measured indirectly by a dilution technique.

False

It increases with age since the elastic recoil of the lungs decreases with age.

155.

True

Via the carotid and aortic bodies.

True

The central effect predominates.

True

Reflex vasoconstriction and cardiac stimulation predominate over the direct
vasodilator effects of CO

True

The cerebral vessels are little affected by sympathetic reflexes so the direct vaso-
dilator effect of CO

predominates.

True

To compensate for the respiratory acidosis.

156.

True

acts centrally by reducing the pH of CSF.

True

Because of the ensuing metabolic acidosis.

False

The metabolic alkalosis depresses ventilation.

False

Ventilation falls during deep sleep.

False

Arterial P

is well maintained in exercise.

157.

True

It makes it more negative by raising blood pH.

False

It decreases as protein binding of calcium increases.

False

Alveolar P

cannot exceed the P

of the air being breathed (160 mmHg, 21 kPa).

False

The blood is normally almost fully saturated (95–98 per cent).

True

To compensate for the respiratory alkalosis.

158.

False

Raised P

can still stimulate breathing by acting on central chemoreceptors.

True

In fact, hypoxia depresses ventilation by its action on the respiratory centre.

False

Normal ventilation is driven mainly by the effect of CO

on central chemorecep-

tors.

False

Central and other peripheral effects increase respiratory drive in exercise.

True

The individual is unable to increase ventilation in response to hypoxia.

MCQ

Respiratory system – questions

Questions 159–165

159. Pulmonary

Arterial mean pressure is about one-sixth systemic mean arterial pressure.

Blood flow/minute is similar to systemic blood flow/minute.

Vascular resistance is about 50 per cent that of systemic vascular resistance.

Vascular capacity is similar to systemic vascular capacity.

Arterial pressure increases by about 50 per cent when cardiac output rises by 50 per
cent.

160. Carbon dioxide is carried in the blood in

Combination with the haemoglobin molecule.

Combination with plasma proteins.

Physical solution in plasma.

Greater quantity in red blood cells than in plasma.

Greater quantity as HCO

⫺

ions than as other forms.

161. A shift of the oxygen dissociation curve of blood to the right

Occurs in the pulmonary capillaries.

Occurs if blood temperature rises.

Favours oxygen delivery to the tissues.

Favours oxygen uptake from the lungs by alveolar capillary blood.

Increases the P

(the P

value giving 50 per cent blood oxygen saturation).

162. The work of breathing increases when

Lung compliance increases.

The subject exercises.

The rate of breathing increases even though the minute volume stays constant.

The subject lies down.

Functional residual capacity increases.

163. The compliance of the lungs and chest wall is

Expressed as volume change per unit change in pressure.

Minimal during quiet breathing.

Increased by the surface tension of the fluid lining the alveoli.

Increased by surfactant.

Changed by parallel displacement of the line relating lung volume to distending pres-
sure.

164. Respiratory dead space

Saturates inspired air with water vapour before it reaches the alveoli.

Removes all particles from inspired air before it reaches the alveoli.

Decreases when blood catecholamine levels rise.

Decreases during a deep inspiration.

Decreases during a cough.

165. Vital capacity is

The volume of air expired from full inspiration to full expiration.

Reduced as one grows older.

Greater in men than in women of the same age and height.

Related more to total body mass than to lean body mass.

The sum of the inspiratory and expiratory reserve volumes.

MCQ

Respiratory system – answers

Answers

159.

True

About 15 compared with 90 mmHg in the systemic circuit.

True

Otherwise blood would accumulate in one or other bed.

False

From (A) and (B) above, it is only about 17 per cent of systemic resistance.

False

Its capacity is about one-third of systemic capacity.

False

Pulmonary vascular resistance falls when cardiac output rises, due possibly to
endothelial release of nitric oxide.

160.

True

Attached to amino groups as carbaminohaemoglobin (Hb-NH.COOH).

True

Attached to amino groups as carbaminoprotein (Pr-NHCOOH).

True

It is the CO

in solution that exerts the P

and is diffusible.

False

Plasma carries the greater quantity, mainly as bicarbonate.

True

Bicarbonate accounts for 80–90 per cent of the total CO

in blood.

161.

False

It occurs in the systemic capillaries.

True

This occurs when tissue metabolic activity increases.

True

More oxygen is released at any given P

False

Less oxygen is taken up at any given P

True

For example, a rise in temperature raises the P

162.

False

Compliant lungs are easier to inflate.

True

Since the rate and depth of ventilation are increased.

True

The work of breathing is minimal around the normal rate of breathing.

True

The increase in pulmonary blood volume increases lung stiffness and abdominal
pressure on the diaphragm rises.

True

Lung compliance falls at higher lung volumes.

163.

True

The normal value is about 0.1 litre/cm H

O (1 litre/kPa).

False

It is maximal over this range of chest movement.

False

The surface tension of alveolar fluid decreases compliance.

True

This decreases the surface tension.

False

The slope of this line indicates compliance and is unchanged by a parallel shift.

164.

True

This prevents drying of the alveolar surface.

False

Particles less than about two microns can reach the alveoli.

False

Catecholamines relax airway muscle and constrict mucosal vessels.

False

Expansion of the lungs expands airways as well as alveoli.

True

This allows air to be expelled at high airway velocity.

165.

True

This is how it is usually measured.

True

It falls on average by about a litre between age 20 and age 70.

True

By half to one litre.

False

It is related closely to lean body mass.

False

The tidal volume must be added.

MCQ

Respiratory system – questions

Questions 166–171

166. In pulmonary capillary blood

Carbonic anhydrase in erythrocytes catalyses the formation of H

⫹

and HCO

⫺

Hydrogen ions dissociate from haemoglobin.

The rise in P

is of greater magnitude than the fall in P

The oxygen content is linearly related to alveolar P

The pH is lower than in blood in the pulmonary artery.

167. Oxygen debt is

The amount of O

consumed after cessation of exercise.

Incurred because the pulmonary capillary walls limit O

uptake during exercise.

Possible since skeletal muscle can function temporarily without oxygen.

Associated with a rise in blood lactate.

Associated with metabolic acidosis.

168. The CO

dissociation curve for whole blood shows that

Its shape is sigmoid.

Blood saturates with CO

when P

exceeds normal alveolar levels.

Blood contains some CO

even when the P

is zero.

Oxygenation of the blood drives CO

out of the blood.

Adding CO

to the blood drives O

out of the blood.

169. The oxygen content of mixed venous blood is

Measured using blood sampled from the right atrium.

Increased during generalized muscular exercise.

Increased in a warm environment.

Increased in cyanide poisoning.

Decreased in circulatory failure.

170. Bronchial asthma is likely to be relieved by

Stimulation of cholinergic receptors.

Stimulation of beta adrenoceptors.

Histamine aerosols.

Drugs which stabilize mast cell membranes.

Glucocorticoids.

171. Air in the pleural cavity (pneumothorax)

Allows intrapleural pressure to rise to atmospheric pressure.

Causes the underlying lung to collapse by compressing it.

Increases the functional residual capacity.

Leads to a slight outward movement of the chest wall.

Reduces vital capacity.

MCQ

Respiratory system – answers

Answers

166.

False

It catalyses the conversion of H

to CO

and H

True

Oxygenation of haemoglobin favours this dissociation.

True

rises by at least 40 mmHg whereas P

falls by only 6 mmHg.

False

It follows the sigmoid oxygen dissociation curve.

False

It is higher due to the diffusion of CO

out of the blood to the alveoli.

167.

False

It is the amount of O

in excess of resting needs consumed after exercise stops.

False

uptake across pulmonary capillary walls is not usually diffusion limited.

True

The O

debt incurred during anaerobic metabolism is repaid later.

True

This is generated during anaerobic metabolism.

True

Due to the lactic acid, blood HCO

⫺

falls as the lactic acid is buffered.

168.

False

The curves start and ﬁnish differently. The CO

curve has a steep initial slope

which gradually decreases, but there is no plateau. It is the O

curve which is sig-

moid in shape.

False

Content continues to rise as P

rises above normal alveolar levels.

False

content is zero when P

is zero.

True

Oxyhaemoglobin is a stronger acid than reduced haemoglobin; the liberated
H

⫹.

ions drive the reaction H

⫹

⫹HCO

⫺

→ H

→ CO

⫹H

False

This is shown by the oxygen dissociation curve, not the carbon dioxide dissoci-
ation curve.

169.

False

For adequate mixing, pulmonary artery blood is needed.

False

It falls due to increased oxygen extraction by the active muscles.

True

Due to large volumes of well oxygenated blood returning from skin.

True

Cyanide blocks uptake of oxygen by tissue enzyme systems.

True

Oxygen extraction is increased in stagnant hypoxia.

170.

False

This causes bronchoconstriction.

True

This causes relaxation of bronchial muscle.

False

Histamine is a bronchoconstrictor.

True

The chromoglycate drugs are thought to work like this and reduce release of
bronchoconstrictor agents from mast cells.

True

These suppress bronchoconstrictor and inflammatory mechanisms.

171.

True

Air flows in since the pressure in the cavity is normally subatmospheric.

False

Except in tension pneumothorax, pleural pressure does not exceed intrapulmo-
nary pressure (atmospheric); collapse is due to elastic recoil of the lungs.

False

It decreases as the lung collapses.

True

The elastic recoil of the lung is no longer applied to the chest wall.

True

The lungs cannot be fully inflated.

MCQ

Respiratory system – questions

Questions 172–177

172. A patient with chronic respiratory failure

Shows an enhanced respiratory sensitivity to inhaled carbon dioxide.

Shows little or no respiratory response to hypoxia.

Is likely to have a low blood bicarbonate level.

Responds well when given 100 per cent oxygen to breathe.

Must have been breathing oxygen-enriched air if alveolar P

is 150 mmHg (20 kPa).

173. Loss of pulmonary elastic tissue in ‘emphysema’ reduces

Physiological dead space.

Anatomical dead space.

Residual volume.

Vital capacity.

The percentage of the vital capacity expired in one second.

174. Complete obstruction of a major bronchus usually results in

Collapse of the alveoli supplied by the bronchus.

A rise in local intrapleural pressure.

An increase in physiological dead space.

An increase in blood flow to the lung tissue supplied by the bronchus.

Cyanosis.

175. A shift of the oxygen dissociation curve of blood to the left

Decreases the O

content of blood at a given P

Impairs O

delivery to the tissues at the normal tissue P

Occurs in blood perfusing cold extremities.

Occurs in blood stored for several weeks.

Is characteristic of fetal blood when compared with adult blood.

176. Obstructive airways disease (COPD) is similar to restrictive lung disease

(RLD) in that it reduces

Vital capacity (VC).

The forced expiratory volume in one second (FEV

The ratio FEV

/VC.

Residual volume.

Peak expiratory flow rate to the same degree.

177. A diver breathing air at a depth of 30 metres under water

Is exposed to a pressure of about four times that at the surface.

Has a raised pressure of nitrogen in the alveoli.

Has a four-fold increase in the oxygen content of blood.

Has a four-fold increase in alveolar water vapour pressure.

Expends less energy than normal on the work of breathing.

MCQ

Respiratory system – answers

Answers

172.

False

There is increased tolerance of high P

levels.

False

Sensitivity to low P

remains and is important in maintaining ventilation.

False

HCO

⫺

levels rise to compensate for the raised P

in respiratory acidosis.

False

This could arrest ventilation by removing hypoxic drive; 24–28 per cent O

would

do.

True

When breathing air, P

⫹P

equal about 140 mmHg (19 kPa).

173.

False

It increases as the walls between alveoli break down to form large sacs.

True

Destruction of elastic ﬁbres holding airways open allows them to narrow.

False

It is increased as airways close more readily than usual during expiration.

True

It decreases as the residual volume increases.

True

Thus it is a typical obstructive airways disease.

174.

True

This ‘atelectasis’ is due to absorption of trapped air.

False

Local collapse of the lung lowers local intrapleural pressure.

False

Since the affected lung is collapsed it does not count as dead space.

False

Local hypoxia in the unventilated segment causes local vasoconstriction.

False

Vasoconstriction in the collapsed segment prevents deoxygenated blood passing
through to the systemic circulation.

175.

False

It increases content, especially at tissue P

True

The blood does not release its oxygen adequately.

True

Cold shifts the curve to the left and may reduce O

delivery to cold tissues.

True

Such blood when transfused may not release its O

content adequately.

True

Fetal blood can thus take up O

at the low P

levels seen in the placenta but fetal

tissue P

has to be low to permit its release.

176.

True

In COPD by air trapping and in RLD by reducing total lung volume.

True

In COPD by slowing flow and in RLD by restricting volume.

False

Only COPD which slows flow reduces it.

False

It rises in COPD and falls in RLD.

False

COPD typically causes marked reduction, RLD typically has little effect.

177.

True

10 metres of water

⫽approximately one atmosphere.

True

Total alveolar pressure

⫽four atmospheres.

False

Haemoglobin is already saturated with O

at sea level and cannot take up more;

the amount of dissolved oxygen increases raising total O

content by less than 10

per cent.

False

This depends on temperature alone.

False

More energy is needed to move air made more viscous by compression.

MCQ

Respiratory system – questions

Questions 178–183

178. Cyanosis

May be caused by high levels of carboxyhaemoglobin in the blood.

May be caused by high levels of methaemoglobin in the blood.

Is seen in ﬁngers of hands immersed in iced water.

Occurs more easily in anaemic than in polycythaemic patients.

Is severe in cyanide poisoning.

179. A patient with carbon dioxide retention is likely to have

Metabolic acidosis.

Alkaline urine.

Cool extremities.

Raised cerebral blood flow.

Raised plasma bicarbonate.

180. Surgical removal of one lung reduces the

FEV

by about 10 per cent.

Percentage saturation of arterial blood with oxygen.

Exercise tolerance.

Residual volume.

Ventilation/perfusion ratio by about 50 per cent.

181. Coughing

Is reflexly initiated by irritation of the alveoli.

Is associated with relaxation of airways smooth muscle.

Depends on contraction of the diaphragm for expulsion of air.

Differs from sneezing in that the glottis is initially closed.

Is depressed during anaesthesia.

182. The severity of an obstructive airways disease is indicated by the degree

of change in the

Total ventilation/perfusion ratio.

Peak expiratory flow rate.

Respiratory quotient.

Tidal volume.

Work of breathing.

183. A 50 per cent fall in the ventilation/perfusion ratio in one lung would

Lower systemic arterial oxygen content.

Have effects similar to those of a direct right to left atrial shunt.

Increase the physiological dead space.

Lower systemic arterial carbon dioxide content.

Be compensated (with respect to oxygen uptake) by a high ratio in the other lung.

MCQ

Respiratory system – answers

Answers

178.

False

Carboxyhaemoglobin is pink and gives the skin a pinkish colour.

True

This blue pigment is a rare cause of central cyanosis.

False

The ﬁngers are red; cold inhibits oxygen dissociation and reduces metabolism.

False

Cyanosis occurs when arterial blood contains more than 5 g/dl reduced haemo-
globin; low haemoglobin values in anaemia make it difﬁcult to reach this level.

False

Cyanide poisons the enzymes involved in O

uptake by the tissues; in cyanide

poisoning the blood remains fully oxygenated and the skin is pink.

179.

False

retention causes respiratory acidosis.

False

In respiratory acidosis there is increased secretion of H

⫹

ions in urine.

False

Carbon dioxide dilates peripheral blood vessels.

True

The vasodilator effect of high P

on cerebral vessels may lead to cerebral

oedema and headaches.

True

The kidney manufactures bicarbonate to compensate the respiratory acidosis.

180.

False

It reduces it by at least half.

False

A single lung can maintain normal oxygenation at rest.

True

Maximum ventilation and maximum oxygen uptake are reduced.

True

It leads to a restrictive lung disease pattern.

False

The ratio is little affected.

181.

False

It is initiated by irritation of the trachea and bronchi.

False

Contraction narrows airways and increases velocity of flow.

False

It depends on expiratory muscles, particularly abdominal muscles.

True

Thus it is more explosive than sneezing.

True

This may lead to retention of mucous secretions.

182.

False

It may well be normal.

True

It is a sensitive indicator.

False

RQ is related to the mixture of substrates being metabolized.

False

This also may be normal.

True

This is related to the increased airway resistance.

183.

True

It constitutes a physiological shunt.

True

This would be an anatomical shunt.

False

Physiological dead space is relatively overventilated.

False

It would tend to raise it.

False

Increased ventilation cannot increase oxygen saturation; compensation for
carbon dioxide retention can occur.

MCQ

Respiratory system – questions

Questions 184–187

184. In the forced expiratory volume (FEV

) measurement, an adult patient

With normal lungs should expire 95 per cent of vital capacity (VC) in 1 second.

With restrictive disease may expire a greater than predicted per cent of VC in the ﬁrst
second.

Who is female would be expected to expire a greater per cent of VC in 1 second than a
male of the same age.

With obstructive disease may take more than 5 second to complete the expiration.

With normal lungs should achieve a peak flow rate of at least 200 litres/minute.

185. The hypoxia in chronic respiratory failure

May cause central cyanosis.

May cause peripheral cyanosis.

Leads to increased formation of erythropoietin.

Raises pulmonary vascular resistance.

May lead to right heart failure.

186. ‘Blue Bloaters’ (patients with chronic obstructive pulmonary disease

showing marked cyanosis and oedema) differ from ‘Pink Puffers’
(patients with chronic obstructive pulmonary disease showing dyspnoea
but not cyanosis) by having a lower

Forced expiratory volume in one second.

Peak expiratory flow rate.

Arterial blood pH.

Sensitivity to carbon dioxide.

Pulmonary arterial pressure.

187. The total amount of O

carried by the circulation to the tissues/min.

(oxygen delivery or total available oxygen)

Normally equals the rate of O

consumption by the body/min.

Is normally more than 95 per cent combined with haemoglobin.

Must fall by about half if haemoglobin concentration is halved.

Is more closely related to P

than to percentage saturation of the blood with O

Must double if body oxygen consumption doubles.

MCQ

Respiratory system – answers

Answers

184.

False

The normal is about 85 per cent at age 20, falling to about 70 per cent at age
60–70.

True

The airways are not obstructed and vital capacity volume is reduced.

True

Females have, on average, smaller vital capacities than males.

True

This is typical of moderately severe obstructive airways disease.

True

200 litres/min is a low ﬁgure; most subjects, other than small elderly females,
should do better.

185.

True

Reduced V/P ratios allow deoxygenated blood to be shunted to the left side of the
heart.

False

The peripheral circulation in chronic respiratory failure is usually adequate.

True

This in turn leads to the secondary polycythaemia typical of the condition.

True

Hypoxia constricts pulmonary vessels and may cause pulmonary hypertension.

True

Persistent pulmonary hypertension can lead to right heart failure.

186.

False

This is not a differentiating feature.

False

This tends to parallel the FEV

True

They have a respiratory acidosis due to CO

retention.

True

They do not respond adequately to their high P

False

Pulmonary hypertension in ‘Blue Bloaters’ leads to heart failure and oedema.

187.

False

At rest, O

consumption (about 250 ml/min) is about 25 per cent of the total

available.

True

All but 3 of the 200 ml/l is combined with haemoglobin, the rest is dissolved.

False

In anaemic hypoxia, cardiac output rises to compensate for the reduced oxygen
content per litre of blood.

False

If P

falls by 25 per cent from normal, there is relatively little change in the

blood oxygen content.

False

The extraction ratio rises as oxygen consumption rises, e.g. during exercise.

MCQ

RESPIRATORY SYSTEM

EMQs

Questions 188–194

EMQ Question 188

For each description of respiratory pressures A–E, select the most appropriate option from the
following list.

1. Intrapleural pressure.

2. Intra-abdominal pressure.

3. Intra-alveolar pressure.

4. Intra-oesophageal pressure.

5. Atmospheric pressure.

Intra-alveolar pressure at end-inspiration and end-expiration.

Shows transient rises and falls during the respiratory cycle peaking at mid-expiration
and mid-inspiration respectively.

Approximates to intrapleural pressure.

Rises markedly during the vomiting reflex.

Determines the pressure gradient for inspiration and expiration.

EMQ Question 189

For each person described below A–E, select the most appropriate set of arterial blood gas
results (pH and bicarbonate are included) from the following list.

Bicarbonate

Normal

Reduced

Normal

Reduced

Increased

Normal

Reduced

Increased

Reduced

Increased

Reduced

Increased

Reduced

Increased

Reduced

Normal

Increased

Reduced

A healthy 25-year-old has climbed from sea level to a height of 1000 metres (about
3000 feet), feels ﬁne and is enjoying the view.

A 40-year-old known diabetic on insulin has been admitted to hospital, semi-conscious
with ketoacidosis and is breathing deeply.

A healthy 30-year-old is on a high-altitude adventure holiday with initially several days
at moderate altitude where ventilation is deﬁnitely increased. Later, while climbing at
4500 metres (about 15 000 feet) severe headache, retching and inability to continue
climbing develop.

A 55-year-old patient with long-standing cough and sputum has been admitted with
signs of serious chest infection and a general bluish colour. Initial treatment has
included treatment with oxygen through a facemask.

A 30-year-old is admitted to hospital with signs of serious renal damage. The patient is
drowsy and is breathing deeply.

EMQ

Respiratory system – answers

Answers for 188

Option 5

Atmospheric pressure. Intra-alveolar pressure returns to atmospheric pres-

sure at the end of each inspiratory and expiratory phase.

Option 3

Intra-alveolar pressure. This dips transiently during inspiration and rises to

a similar extent during expiration.

Option 4

Intra-oesophageal pressure. Since the oesophagus and the intrapleural

spaces are normally closed cavities within the chest, intra-oesophageal pressure normally
approximates to intrapleural pressure.

Option 2

Intra-abdominal pressure. During vomiting this rises markedly to compress

the gut while the way out through the lower oesophageal (cardiac) sphincter is open due
to relaxation of oesophageal smooth muscle.

Option 3

Intra-alveolar pressure. The difference between this and atmospheric pres-

sure constitutes the pressure gradient which determines the flow of air into or out of the
lungs.

Answers for 189

Option 2

reduced, others normal. At 1000 metres, atmospheric pressure and hence

ambient oxygen pressure fall by about 10 per cent. This reduces alveolar and hence arte-
rial P

by slightly more, since alveolar water vapour pressure and P

do not change.

However, due to the plateau of the oxygen dissociation curve, arterial saturation falls only
slightly. Bodily function is unaffected, with no change in ventilation, so carbon dioxide,
pH and bicarbonate do not change.

Option 6

All reduced, apart from Po

, which is increased. The ketoacidosis is due to

abnormal accumulation of highly acidic metabolites. Hence the pH is reduced. Bicarbonate
ions have buffered most of the surplus hydrogen ions to minimize the fall in pH, hence
bicarbonate is reduced. The acidosis stimulates ventilation. This reduces P

and also

limits pH fall; the increased ventilation also increases P

, though as in (A) the effect on

saturation is minute.

Option 8

pH increased, others reduced. In this case, serious ‘hypoxic hypoxia’ leads

to increased ventilation reflexly via the carotid and aortic bodies. Increased ventilation
improves P

, but it remains well below normal, causing general tissue hypoxia. The

increased ventilation acts mainly by lowering P

, allowing oxygen to replace some of

the carbon dioxide in the alveoli. However, lowered P

causes a respiratory alkalosis so

pH rises. To compensate for the respiratory alkalosis, the renal tubules reduce secretion of
hydrogen ions and lower blood bicarbonate level. However, all these compensations
merely reduce the abnormalities. The combination of tissue hypoxia, decreased cerebral
blood flow (due to the low P

), and alkalosis seriously disturb bodily function. Some

people tolerate this quite well, but others, like this person, feel wretched and are at risk of
serious and even fatal complications.

Option 5

pH reduced, others increased. The 55-year-old has inadequate ventilation

related to chronic respiratory disease. The inadequate ventilation is shown by the bluish
colour (cyanosis) due to excessive desaturated haemoglobin. This is another variety of
‘hypoxic hypoxia’. The inadequate ventilation also raises the P

, causing a respiratory

acidosis. As with (C), but in the opposite direction, the renal tubules raise the blood bicar-
bonate level. The increased P

can only be explained by the administration of oxygen.

Before this the oxygen level would have been reduced. Such patients require careful mon-
itoring of their blood gases and control of the administered oxygen.

Option 6

All reduced, apart from P

, which is increased. Here the renal damage

impairs hydrogen ion excretion in the urine and addition of bicarbonate to the blood. Just
like (B) this patient has a metabolic acidosis. The respiratory compensation and its effects
are explained in the same way.

EMQ

Respiratory system – questions

EMQ Question 190

For each person A–E, select the most appropriate set of results for respiratory function tests
from the following list, where VC

⫽vital capacity; FEV

1.0

⫽forced expiratory volume in one

second; RV

⫽residual volume all litres; PEFR⫽peak expiratory flow rate in litres per second.

FEV

1.0

FEV

1.0

/VC

Per cent

PEFR

5.0

4.0

1.5

600

3.0

2.1

1.2

350

4.5

5.0

1.2

200

4.0

2.0

2.5

120

3.0

2.4

0.8

620

4.0

3.4

1.2

450

A woman of 19 years who had occasional asthma as a child but is now free of symp-
toms.

A man of 32 who is having respiratory function testing as part of a routine health
check.

A woman of 77 who is acting as a normal control in a research project.

When this patient comes to discuss the results of respiratory testing, the doctor apolo-
gizes that there seems to have been a mistake as the results do not make sense.

A man of 45 with a long history of chronic obstructive pulmonary disease (COPD).

EMQ Question 191

For each item A–E related to control of ventilation, select the most appropriate option from the
list below.

1. Voluntary hyperventilation.

2. Reflex hyperventilation.

3. Hypoventilation.

4. Ventilation controlled from the medulla

5. Ventilation controlled from above

oblongata.

the medulla oblongata.

6. Ventilation associated with dyspnoea.

An athlete’s ventilation may increase from a normal value of 6 litres per minute to over
100 litres per minute while running a race.

A student breathes a mixture of 5 per cent carbon dioxide and ﬁnds that, without
apparent effort, the breathing is much deeper than normal.

Another student is asked to breathe rapidly and deeply for three minutes. Towards the
end of the time there is a strong wish to reduce the breathing and there is a feeling of
lightness and discomfort in the head.

In normal people breathing continues steadily during sleep.

In people with COPD the lungs are over-inflated and it may be harder to breathe in than
breathe out.

EMQ

Respiratory system – answers

Answers for 190

Option 6

This is a normal vital capacity for a young female where volumes are smaller

than in males. FEV1

1.0

is 85 per cent of VC which is normal in young people; RV is also

in keeping. PEFR is also normal for a female. Option 2 would be the next best option but
note the comments in (C).

Option 1

These are all normal values for an average male of this age.

Option 2

These are normal values for a woman of this age. VC is smaller in females

and falls with age. FEV

1.0

/FVC also falls with age and this is normal at her age. RV tends

to rise with age, although the value is quite small it is a higher proportion of total lung
capacity (VC

⫹RV) here than in Option 1. This is a normal PEFR for a woman of this age.

Option 3

This is a nonsense result. FEV

1.0

cannot be greater than VC; they may have

been reversed, which would correspond with the percentage of 90. However, these results
would not then correspond with the low PEFR.

Option 4

These results are typical of fairly severe COPD. FEV

1.0

is only half the vital

capacity, RV is considerably increased and PEFR is much reduced. The changes would be
those expected in someone whose predicted normal results correspond to Option 1. If this
man had developed restrictive disease, then Option 5 would be appropriate parallel reduc-
tions in all volumes including RV, but a well preserved and even increased PEFR as the
airways are not affected by restrictive disease.

Answers to 191

Option 4

Ventilation controlled from above the medulla oblongata. The commonest sit-

uation for this huge minute volume is strenuous exercise in a normal person. This is not
a reflex from a fall in arterial oxygen levels, which remain normal, but is controlled from
higher levels where circulatory and respiratory activities are coordinated with muscular
activity. This activity is sometimes identiﬁed with ‘the exercise centre’ though this is more
a function of the brain than a localized area.

Option 2

Reflex hyperventilation. The increased ventilation is reflexly produced via

chemoreceptors in the region of the medulla oblongata. These respond to the huge rise in
hydrogen ions produced centrally from the rise in carbon dioxide level.

Option 1

Voluntary hyperventilation. The hyperventilation lowers the carbon dioxide

level. This causes a respiratory alkalosis and constricts cerebral arterioles. There has been
a suggestion that people who are most distressed by this activity are the most likely to
suffer from severe symptoms at high altitudes where such changes are the result of reflex
hyperventilation.

Option 4

Ventilation controlled from the medulla oblongata. The spontaneous rhyth-

micity in the inspiratory and expiratory centres here generate the basic breathing pattern
upon which other more complicated activities, including voluntary control as in respira-
tory function testing, are built.

Option 6

Ventilation associated with dyspnoea. With severe over-inflation lung com-

pliance falls; this increases the work of breathing in and may be less severe when breath-
ing out (patients vary in this). The extra effort is interpreted as something wrong with the
breathing (dyspnoea means bad breathing). In Option 1 the problem is not with the breath-
ing but with the effects it produces. In Option 2 the increased breathing is not experienced
as particularly unpleasant. In Option 5 the increased breathing of exercise is recognized
as normal.

EMQ

Respiratory system – questions

EMQ Question 192

For each item A–E related to oxygen transport, select the most appropriate option from the list
below:

1. Sigmoid.

2. Plateau.

3. Oxygen in solution.

4. Percentage saturation.

5. Oxygen content, ml oxygen per

6. Shift of the curve to the right.

litre of blood.

7. Shift of the curve to the left.

When the y axis of the oxygen dissociation curve of blood is labelled thus, the curve for
severe anaemia is very similar to that for normal blood.

The form in which oxygen passes from blood to tissues.

This leads to proportionately greater release of oxygen to the tissues.

A property of the oxygen dissociation curve which is related to the varying afﬁnities of
haemoglobin for oxygen particularly at very low oxygen pressures and at the pressures
around the normal range for alveolar oxygen pressures.

The reason the ‘plateau’ phase of the oxygen dissociation curve is not completely hori-
zontal.

EMQ Question 193

For each item A–E related to carbon dioxide transport, select the most appropriate option from
the list below.

1. Dissolved carbon dioxide.

2. Carbon dioxide combined with

3. Carbon dioxide in red cells.

haemoglobin.

4. Carbon dioxide in plasma.

5. Carbaminohaemoglobin.

6. Carboxyhaemoglobin.

7. Ability of desaturated haemoglobin to

buffer hydrogen ions.

This has a particularly unfavourable effect on the ability of blood to carry adequate
oxygen.

The action of carbonic anhydrase is particularly important here.

The relationship of this to partial pressure is quantitatively different than is the case
with oxygen.

This favours carriage of carbon dioxide by the law of mass action.

This form of transport is influenced more by the saturation of the haemoglobin with
oxygen than the partial pressure of carbon dioxide in the blood.

EMQ

Respiratory system – answers

Answers for 192

Option 4

Percentage saturation. Regardless of the haemoglobin content, the oxygen

content of blood at a given oxygen pressure will always be very similar, expressed as a
percentage of the capacity. The very slight differences are due to the fact that in severe
anaemia the amount of dissolved oxygen relative to oxygen combined with haemoglobin
is slightly greater since there is a higher proportion of plasma.

Option 3

Oxygen in solution. Only dissolved gases can pass through the tissue fluids.

Option 6

Shift of the curve to the right. When the oxygen dissociation curve of blood

shifts to the right on the x axis, the oxygen content of blood at a given oxygen pressure
shifts downwards on the y axis. Thus the blood retains less oxygen and more is released
to the tissues.

Option 1

Sigmoid. Sigmoid means S-shaped. The ﬁrst bend of the S is produced by

the increasing afﬁnity of haemoglobin for oxygen; at low pressures the curve becomes
increasingly steep and then straightens to a steep fairly linear rise. The second bend is pro-
duced as full saturation is approached and the steep rise curves to join the plateau.

Option 3

Dissolved oxygen. As the partial pressure of oxygen increases above the

normal alveolar value, the content rises very gradually as the dissolved oxygen increases
in proportion to the pressure. In hyperbaric oxygen conditions this dissolved amount can
be signiﬁcant. For example if 3 ml are dissolved per litre when P

is 100 mmHg

(13.5 kPa), then at two atmospheres of oxygen, with a P

around 1500 mmHg (200 kPa),

the dissolved oxygen amounts to 45 ml/litre. This can be helpful when haemoglobin has
been disabled by combination with carbon monoxide.

Answers for 193

Option 6

Carboxyhaemoglobin. This is formed when people breathe even low concen-

trations of carbon monoxide. The great afﬁnity of carbon monoxide for haemoglobin dis-
places most of the oxygen so that most haemoglobin is rendered useless and the patient
suffers from potentially fatal anaemic hypoxia.

Option 3

Carbon dioxide in red cells. Carbonic anhydrase is located in red cells rather

than plasma. It provides the necessary acceleration of the formation of carbonic acid and
hence bicarbonate during the short time available for the uptake of carbon dioxide at
tissue level. Without it the dissolved carbon dioxide would build up a pressure which
would seriously slow diffusion from the tissues.

Option 1

Dissolved carbon dioxide. At any given partial pressure carbon dioxide is

many times more soluble than oxygen.

Option 7

Ability of desaturated haemoglobin to buffer hydrogen ions. As mentioned in

(B), generation of bicarbonate is necessary for adequate carriage of carbon dioxide.
Desaturated haemoglobin has a greater ability to buffer hydrogen ions than has oxy-
haemoglobin. The law of mass action predicts that the removal of hydrogen ions by buf-
fering favours further conversion of carbon dioxide to bicarbonate. In addition, diffusion
of bicarbonate ions from red cells to plasma lowers the concentration of the other prod-
uct of the reaction.

Option 5

Carbaminohaemoglobin. Oxyhaemoglobin cannot carry as much CO

in the

carbamino compound as can reduced haemoglobin.

EMQ

Respiratory system – questions

EMQ Question 194

For each item A–E related to oxygen delivery and uptake by tissues, select the most appropri-
ate option from the list below.

1. Total available oxygen.

2. Cardiac output.

3. Blood haemoglobin concentration.

4. Arterial blood oxygen saturation.

5. Venous blood oxygen saturation.

6. Pulmonary arterial blood oxygen

saturation.

Abnormality here is the fundamental cause of hypoxic hypoxia at high altitudes.

The normal value for this in the resting average adult is around one litre per minute.

Abnormality here is the fundamental cause of anaemic hypoxia.

Abnormality here is the fundamental cause of hypoxic hypoxia in respiratory disease.

This is reduced in stagnant hypoxia, in anaemic hypoxia and also in hypoxic hypoxia.

EMQ

Respiratory system – answers

Answers to 194

Option 4

Arterial blood oxygen saturation. At high altitudes the alveolar oxygen pres-

sure falls to levels at which blood passing through the lungs is inadequately saturated with
oxygen. Therefore arterial blood oxygen saturation is seriously reduced and this is the
fundamental cause of impaired delivery of oxygen at high altitudes.

Option 1

Total available oxygen. This equals the oxygen in ﬁve litres of normally sat-

urated blood with a normal haemoglobin content.

Option 3

Blood haemoglobin concentration. Here the reduction in total available

oxygen is reduced in proportion to the reduction in the blood haemoglobin concentration.

Option 4

Arterial blood oxygen saturation. As with (A) the hypoxic hypoxia is due to

inadequate saturation of blood in the lungs. However this time the cause is impaired lung
function rather than reduced inspired oxygen.

Option 1

Total available oxygen. This depends on cardiac output, blood oxygen capac-

ity and arterial blood saturation percentage. Impaired cardiac output causes stagnant
hypoxia, impaired blood oxygen capacity causes anaemic hypoxia and reduced arterial
blood saturation causes hypoxic hypoxia.

EMQ

ALIMENTARY SYSTEM

MCQs

Questions 195–199

195. Bile

Contains enzymes required for the digestion of fat.

Contains unconjugated bilirubin.

Salts make cholesterol more water-soluble.

Pigments contain iron.

Becomes more alkaline during storage in the gallbladder.

196. Saliva

From different salivary glands has a similar composition.

Contains enzymes essential for the digestion of carbohydrates.

Has less than half the ionic calcium level of plasma.

Has more than twice the iodide level of plasma.

Has a pH between 5 and 6.

197. Swallowing is a reflex which

Has its reflex centres in the cervical segments of the spinal cord.

Includes inhibition of respiration.

Is initiated by a voluntary act.

Is dependent on intrinsic nerve networks in the oesophagus.

Is more effective when the person is standing rather than when lying down.

198. Appetite for food is lost when

Certain hypothalamic areas are stimulated.

Certain hypothalamic areas are destroyed.

The stomach is distended.

The stomach is surgically removed.

Blood glucose falls.

199. Secretion of saliva increases when

Touch receptors in the mouth are stimulated.

The mouth is flushed with acid fluids with a pH of about 4.

A subject thinks of unappetizing food.

Vomiting is imminent.

Their sympathetic nerve supply is stimulated.

MCQ

Alimentary system – answers

Answers

195.

False

Bile contains no digestive enzymes; its bile salts assist in the emulsiﬁcation and
absorption of fat.

False

The bilirubin is conjugated by the hepatocytes before excretion.

True

By forming cholesterol micelles.

False

Iron is removed from haem in the formation of bilirubin.

False

It becomes more acid, which improves the solubility of bile solids.

196.

False

Serous glands such as the parotids produce a watery juice; mucous glands such
as the sublinguals produce a thick viscid juice.

False

The functions of salivary amylase (ptyalin) can be affected by enzymes from
other digestive glands.

False

It is saturated with calcium ions; calcium salts are laid down as plaque on the
teeth.

True

Saliva is an important route of iodide excretion; its concentration in saliva is
20–100 times that in plasma.

False

Saliva has a neutral pH; acidity in the mouth tends to dissolve tooth enamel.

197.

False

The reflex centres lie in the medulla oblongata.

True

This plus closure of the glottis prevents food being aspirated into the airways.

True

The voluntary act is propulsion of a bolus of food onto the posterior pharyngeal
wall.

True

These are essential for the peristaltic phase.

True

Gravity can assist the reflex; tablets are more difﬁcult to swallow when lying
down.

198.

True

For example, when the ‘satiety’ centres are stimulated.

True

For example, when the ‘hunger’ centres are damaged.

True

Appetite is relieved after a meal before the food products of digestion are
absorbed into the blood.

False

The drive to eat does not depend on an intact stomach.

False

It increases as hypothalamic ‘glucostats’ detect the low glucose and excite the
‘hunger’ centres to generate the emotional drive to eat.

199.

True

Food, foreign bodies and the dentist are effective stimuli.

True

E.g. lemon juice; saliva is a useful buffer to protect teeth from acid.

False

Thinking of appetizing food results in salivary secretion by a conditioned reflex;
conversely, thinking of unappetizing food inhibits secretion.

True

Saliva helps to buffer the acid vomitus when it reaches the mouth.

True

Sympathetic stimulation produces a scanty viscid juice; parasympathetic stimu-
lation produces a copious watery juice.

MCQ

Alimentary system – questions

Questions 200–205

200. Defaecation is a reflex action

That is coordinated by reflex centres in the sacral cord.

Whose afferent limb carries impulses from stretch receptors in the colon.

Whose efferent limb travels mainly in sympathetic autonomic nerves.

Which is more likely to be initiated just after a meal than just before it.

Which can be voluntarily inhibited or facilitated.

201. Thirst sensation occurs when

Osmoreceptors in the sensory cortex are activated.

Blood osmolality is raised but blood volume is normal.

Blood volume is reduced but blood osmolality is normal.

The mouth is dry.

A patient has severe diabetic keto-acidosis.

202. In the stomach

pH rarely falls below 4.0.

Pepsinogen is converted to pepsin by hydrochloric acid.

Ferrous iron is reduced to ferric iron by hydrochloric acid.

Acid secretion is inhibited by pentagastrin.

There is a rise in the bacterial count after histamine H

receptor blockade.

203. Intestinal secretions contain

Potassium in a concentration similar to that in extracellular fluid.

Enzymes that are released when the vagus nerve is stimulated.

Enzymes that hydrolyze disaccharides.

Enzymes that hydrolyze monosaccharides.

Enzymes that activate pancreatic proteolyic enzymes.

204. Pancreatic secretion

In response to vagal stimulation is copious, rich in bicarbonate but poor in enzymes.

In response to acid in the duodenum is scanty but rich in enzymes.

In response to secretin secretion is low in bicarbonate.

Contains enzymes that digest neutral fat to glycerol and fatty acids.

Contains enzymes that convert disaccharides to monosaccharides.

205. The liver is the principal site for

Synthesis of plasma albumin.

Synthesis of plasma globulins.

Synthesis of vitamin B

Storage of vitamin C.

Storage of iron.

MCQ

Alimentary system – answers

Answers

200.

True

Reflex defaecation can occur after complete spinal cord transection.

False

The stretch receptors triggering the reflex are in the rectal wall.

False

Parasympathetic nerves are the main motor nerves for defaecation.

True

The wish to defaecate that follows a meal is attributed to a ‘gastrocolic reflex’.

True

Forced expiration against a closed glottis facilitates the reflex by raising intra-
abdominal pressure and pushing faeces into the rectum; contraction of the vol-
untary muscle of the external sphincter can inhibit it.

201.

False

The emotional drive to drink depends on ‘thirst centres’ in the hypothalamus.

True

Presumably due to stimulation of hypothalamic osmoreceptors.

True

Presumably due to stimulation of vascular volume receptors.

True

Afferents from the upper alimentary tract can influence ‘thirst centre’ activity.

True

Probably due to osmoreceptor stimulation by the hyperglycaemic blood and a
reduction in the activity of vascular volume receptors.

202.

False

Values around pH 2–3 are normal.

True

Pepsin is the active proteolyic form of pepsinogen.

False

HCl reduces trivalent ferric iron to the divalent ferrous form in which it can be
absorbed in the small intestine.

False

Pentagastrin is a powerful pharmacological stimulant of mucosal cells to produce
HCl.

False

But it rises markedly after H

blockade which blocks gastric acid secretion.

203.

False

The concentration is higher, due partly to potassium released from cast off cells.

False

Intestinal secretion is not under vagal control; its enzymes are thought to be con-
stituents of the mucosal cells and released when these are cast off into the lumen.

True

The mucosal cell brush border contains these enzymes, e.g. maltase and lactase.

False

Monosaccharides are end-products of digestion and absorbed as such.

True

For example, enterokinase which converts trypsinogen to trypsin.

204.

False

It is scanty and rich in enzymes; it is secreted reflexly in the ‘cephalic’ phase of
pancreatic secretion when food is thought about or chewed.

False

It is copious, bicarbonate rich and poor in enzymes; it buffers the acid secretions
entering the duodenum from the stomach.

False

This is the hormone released when acid enters the duodenum that stimulates the
pancreas to produce the juice described in (B) above.

True

Pancreatic lipase.

False

Pancreatic amylase breaks down carbohydrates to dextrins and polysaccharides.

205.

True

Plasma albumin concentration falls in liver failure.

False

Immunoglobulins are produced by ribosomes in lymphocytes.

False

Vitamin B

is ingested in food, absorbed complexed with intrinsic factor in the

terminal ileum and stored in the liver.

False

Vitamin C is not stored; any in excess of requirements is excreted in urine.

True

Iron released from haem from broken down RBCs is stored in the liver for future
haemopoiesis.

MCQ

Alimentary system – questions

Questions 206–211

206. In the colon

A greater volume of water is absorbed than in the small intestine.

Mucus is secreted to lubricate the faecal contents.

Faecal transit time is normally about 7 days.

Faecal transit time is inversely related to its ﬁbre content.

Bacteria normally account for about three quarters of the faecal weight.

207. Gastric juice

Is secreted when the vagus nerves are stimulated.

Is secreted in vagotomized animals when food is chewed but not swallowed.

Inactivates the digestive enzymes secreted with saliva.

Does not digest the gastric mucosa because it is protected by a pepsin inactivator.

Irritates the oesophageal mucosa if regurgitated from the stomach.

208. An increase in body fat increases the

Percentage of water in the body.

Survival time during fasting.

Survival time in cold water.

Speciﬁc gravity of the body.

Probability of increased morbidity and premature mortality.

209. The respiratory quotient

Is the ratio of the volume of O

consumed to the volume of CO

produced.

Depends essentially on the type of substrate being metabolized.

Is 1.0 when glucose is the substrate metabolized.

Is between 0.9 and 1.00 in the second week of fasting.

For the brain is around 1.0.

210. Oxygen consumption tends to increase when the

Concentration of oxygen in inspired air rises.

Metabolic rate falls.

Body temperature rises.

Environmental temperature falls.

After a meal is ingested.

211. Saliva is necessary for

Digestion of food.

Swallowing of food.

Normal speech.

Antisepsis in the mouth.

Taste sensation.

MCQ

Alimentary system – answers

Answers

206.

False

The colon absorbs 1–2 litres/day; 8–10 litres is absorbed per day in the small
intestine.

True

Mucous cells are the predominant cells on the colonic mucosal surface.

False

The average transit time from caecum to pelvic colon is about 12 hours but pas-
sage from the pelvic colon to the anus may take days.

True

Fibre (cellulose, lignin etc.) in the colonic contents stimulates peristaltic move-
ments by adding ‘bulk’ to the food residues.

False

But bacteria such as Escherichia coli make up about a third of faecal weight.

207.

True

Vagal stimulation increases acid and pepsinogen secretion; this action is medi-
ated by acetylcholine and gastrin-releasing peptide released from the vagal nerve
endings.

False

After vagotomy, food must enter the stomach to stimulate gastric secretions.

True

Salivary enzymes are not effective at the low pH of gastric juice.

False

But mucosal cells are protected by a coat of mucus impregnated with bicarbo-
nate.

True

This is normally prevented by the cardiac sphincter.

208.

False

The reverse is true, since fat tissue contains little water

True

Fat is the main energy store of the body.

True

It favours survival by increasing skin insulation.

False

Fat has a lower speciﬁc gravity than the lean body mass.

True

Actuarial tables show this to be true.

209.

False

It is the inverse of this ratio.

True

The respiratory quotients for carbohydrate, fat and protein metabolism are differ-
ent.

True

⫹6O

⫽6CO

⫹6H

O; each molecule of O

consumed results in the pro-

duction of one molecule of CO

False

It approaches 0.7, the value when fat is the main substrate being metabolized.

True

Carbohydrate is the main substrate for brain metabolism.

210.

False

The concentration of oxygen in the air breathed is not a determinant of oxygen
consumption.

False

It rises; metabolic rate is the prime determinant of oxygen consumption.

True

This increases metabolic rate by increasing the rate of cellular metabolism.

True

More thermogenesis is required to maintain body temperature.

True

Due to the speciﬁc dynamic action of the food, particularly protein.

211.

False

Other digestive tract enzymes can take over if salivary enzymes are absent.

False

But swallowing solids is difﬁcult without saliva’s moisturizing and lubricant
effects.

True

Nervous orators with dry mouths continually sip water.

True

In the absence of saliva, the mouth becomes infected and ulceration occurs.

True

Substances must go into solution before they can stimulate taste receptors.

MCQ

Alimentary system – questions

Questions 212–217

212. The stomach

Is responsible for absorbing about 10 per cent of the ingested food.

Contains mucosal cells containing high concentrations of carbonic anhydrase.

Peristaltic contractions start from the pyloric region.

Motility increases when fat enters the duodenum.

Relaxes when food is ingested so that there is little rise in intra-gastric pressure.

213. Brown fat is

Relatively more abundant in adults than in infants.

Richer in mitochondria than ordinary fat.

More vascular than ordinary fat.

Stimulated to generate more heat when its parasympathetic nerve supply is stimulated.

Is more important than shivering in neonatal thermoregulation.

214. Nitrogen balance

Is the relationship between the body’s nitrogen intake and nitrogen loss.

Is positive in childhood.

Becomes more positive when dietary protein is increased.

Becomes negative when a patient is immobilized in bed.

Becomes less negative in the ﬁnal stages of fatal starvation.

215. The normally innervated stomach

Is stimulated to secrete gastric juice when food is chewed, even if it is not swallowed.

Cannot secrete HCl when its H

histamine receptors are blocked.

And the denervated stomach can secrete gastric juice after a meal is ingested.

Empties more quickly than the denervated stomach.

Is stimulated to secrete gastric juice by the hormone secretin

216. The passage of gastric contents to the duodenum may cause

Copious secretion of pancreatic juice rich in bicarbonate.

Decreased gastric motility.

Contraction of the gallbladder.

Contraction of the sphincter of Oddi.

Release of pancreozymin.

217. Bile salts

Are the only constituents of bile necessary for digestion.

Have a characteristic molecule, part water-soluble and part fat-soluble.

Are reabsorbed mainly in the upper small intestine.

Are derived from cholesterol.

Inhibit bile secretion by the liver.

MCQ

Alimentary system – answers

Answers

212.

False

Little food is absorbed in the stomach other than alcohol.

True

This is needed to generate the H

⫹

ions required for HCl secretion; carbonic anhy-

drase inhibitors reduce acid secretion.

False

They begin at the other end, the fundus.

False

Fat in the duodenum inhibits gastric motility.

True

This ‘receptive relaxation’ allows the stomach to store large volumes of food
without discomfort.

213.

False

The reverse is true.

True

It has a higher metabolic rate than ordinary fat.

True

Its higher metabolic rate merits a higher rate of blood flow.

False

Metabolic activity in brown fat is stimulated by sympathetic nerve stimulation.

True

Infants do not shiver well.

214.

True

It is positive when more nitrogen is taken in than is lost.

True

Nitrogen intake is greater than nitrogen loss during active tissue growth.

False

The additional nitrogen intake is balanced by additional nitrogen loss as the extra
protein is metabolized and its nitrogen excreted in the urine.

True

Muscles waste and the protein released is metabolized.

False

It becomes more negative when little but protein remains to be metabolized.

215.

True

This depends on a vagal reflex.

False

Blockade of histamine H

receptors blocks gastric acid secretion.

True

The denervated stomach is still affected by gastrin released from the gastric
mucosa when food enters the stomach.

True

Gastric motility is more effective when it is coordinated by vagal nerve activity.

False

Secretin, which stimulates pancreatic secretion, decreases gastric secretion.

216.

True

This is caused by the hormone secretin released from the duodenal mucosa.

True

This postpones further gastric emptying.

True

Due to the action of cholecystokinin released from the mucosal cells.

False

The sphincter of Oddi must relax to allow bile to enter the gut.

True

Pancreozymin stimulates the pancreas to secrete a scanty, enzyme rich juice.

217.

True

They emulsify fat creating a greater surface area for lipase to act on.

True

This property allows them form to micelles for fat transport.

False

They are absorbed in the terminal ileum.

True

They are synthesized from cholesterol in the liver.

False

They are ‘choleretics’, substances which stimulate bile secretion.

MCQ

Alimentary system – questions

Questions 218–222

218. Absorption of

Fat is impaired if either bile or pancreatic juice is not available.

Undigested protein molecules can occur in the newborn.

Laevo-amino acids occurs more rapidly than absorption of the dextro-forms.

Iron is at a rate proportional to body needs.

Sodium is at a rate proportional to body needs.

219. The specific dynamic action of food

Is the increase in metabolic rate that results from ingestion of food.

Persists for about an hour after a meal is ingested.

Is due to the additional energy expended in digesting and absorbing the food.

Results in about 30 per cent of the energy value of ingested protein being unavailable
for other purposes.

Results in about 20 per cent of the energy value of ingested fat and carbohydrate being
unavailable for other purposes.

220. Secretion of gastric juice

Increases when food stimulates mucosal cells in the pyloric region.

Is associated with a decrease in the pH of venous blood draining the stomach.

In response to food is reduced after vagotomy.

Is essential for protein digestion.

Is essential for absorption of vitamin B

221. In the small intestine

The enzyme concentration in intestinal juice is lower in the ileum than in the jejunum.

Vitamin B

is absorbed mainly in the jejunum.

Water absorption is dependent on the active absorption of sodium and glucose.

Absorption of calcium occurs mainly in the terminal ileum.

Glucose absorption is dependent on sodium absorption.

222. The cells of the liver

Help to maintain the normal blood glucose level.

Deaminate amino acids to form NH

⫹

which is excreted as ammonium salts in the urine.

Synthesize Vitamin D

(cholecalciferol).

Manufacture most of the immune globulins.

Inactivate steroid hormones manufactured in the gonads.

MCQ

Alimentary system – answers

Answers

218.

True

If either is absent, undigested fat appears in the faeces.

True

Maternal antibodies (globulins) in colostrum are so absorbed.

True

Transport mechanisms are isomer-speciﬁc.

True

An active carrier-mediated transport mechanism is involved which reduces the
danger of iron toxicity with excessive intake.

False

Most ingested sodium is absorbed; if absorption is above the body requirements,
the excess is excreted by the kidneys.

219.

True

This is its deﬁnition.

False

It persists for about six hours.

False

It is due mainly to the additional energy expended on processing absorbed
material for detoxification, metabolism and storage.

True

Mainly because of the energy required to deaminate amino acids.

False

The ﬁgures are around 4 per cent for fat and 6 per cent for carbohydrate.

220.

True

Cells in the pylorus release gastrin when food enters the stomach.

False

Venous blood pH rises as bicarbonate enters the circulation in the ‘alkaline tide’.

True

Vagal activity plays an important role in gastric juice secretion.

False

Pancreatic trypsin and chymotrypsin can digest proteins.

True

Without gastric ‘intrinsic factor’, Vitamin B

is not absorbed from the gut.

221.

True

Being proteins, enzymes are digested by proteolytic enzymes as they pass down
the gut.

False

It is absorbed mainly in the terminal ileum.

True

Water is absorbed passively down the osmotic gradient set up by active sodium
and glucose absorption.

False

It occurs mainly in the duodenum.

True

Sodium is required at the luminal surface for glucose to be absorbed by an active
carrier-mediated process.

222.

True

When blood glucose falls, liver glycogen is broken down to form glucose; when
glucose levels rise above normal, glucose is taken up by the liver and stored as
liver glycogen.

False

The NH

⫹

is converted into urea and excreted in the urine; NH

⫹

is toxic.

False

Cholecalciferol in produced in skin by the action of sunlight; the liver converts it
to 25-hydroxycholecalciferol and the kidney completes its activation by further
hydroxylation.

False

They manufacture most of the plasma proteins but lymphocytes manufacture
immune globulins.

True

The failure to inactivate oestrogens in men with liver failure can lead to breast
enlargement.

MCQ

Alimentary system – questions

Questions 223–228

223. Absorption of dietary fat

Can only occur after the neutral fat has been split into glycerol and fatty acids.

Involves fat uptake by both the lymphatic and blood capillaries.

Is impaired following gastrectomy.

Is required for normal bone development.

Is required for normal blood clotting.

224. One gram of

Carbohydrate, metabolized in the body, yields the same energy as when oxidized in a
bomb calorimeter.

Fat, metabolized in the body, yields 10 per cent more energy than 1g of carbohydrate.

Protein, metabolized in the body, yields the same energy as when oxidized in a bomb
calorimeter.

Carbohydrate, metabolized in the body, yields about the same energy as 1g of protein.

Protein per kg body weight is an adequate daily protein intake for a sedentary adult.

225. Cholesterol

Can be absorbed from the gut by intestinal lymphatics following its incorporation into
chylomicrons.

Can be synthesized in the liver.

In the diet comes mainly from vegetable sources.

Is eliminated from the body mainly by metabolic degradation.

Is a precursor of adrenal cortical hormones.

226. Free (non-esterified) fatty acids in plasma

Account for less than 10 per cent of the total fatty acids in plasma.

Are complexed with the plasma proteins.

Decrease when the level of blood adrenaline rises.

Can be metabolized to release energy in cardiac and skeletal muscle.

Can be metabolized to release energy in the brain.

227. The risk of developing gallstones increases

When cholesterol micelles are formed in the gall bladder.

As the bile salt:cholesterol ratio increases.

As the lecithin:cholesterol ratio increases.

When supplementary bile salts are taken by mouth.

In patients with haemolytic anaemia.

228. Modifying gastric function

By cutting vagal ﬁbres to the pylorus increases the emptying rate.

By enlarging the pyloric oriﬁce increases the emptying rate.

By making a side-to-side anastomosis between the stomach and jejunum may cause
peptic ulceration in the jejeunum.

To allow rapid gastric emptying may lead to low blood glucose levels after a meal.

To allow rapid gastric emptying may lead to a fall in blood volume and blood pressure
after a large meal.

MCQ

Alimentary system – answers

Answers

223.

False

Unsplit neutral fat can be absorbed if emulsiﬁed into sufﬁciently small particles.

True

The smaller fatty acids pass directly into blood; the larger ones are esteriﬁed,
packaged into chylomicrons and taken into lymphatics.

True

The loss of gastric storage capacity results in rapid transit of food through the
small intestine and insufﬁcient time for complete digestion and absorption of fat.

True

Vitamin D is required for normal bone development; it is a fat-soluble vitamin
and absorbed along with the fat.

True

Vitamin K which is needed for the synthesis of certain clotting factors in the liver
is also a fat-soluble vitamin.

224.

True

In both cases the carbohydrate is oxidized to carbon dioxide and water.

False

Fat yields approximately 125 per cent more energy.

False

It yields about 40 per cent less when metabolized in the body, urea derived from
protein is excreted in the urine and its free energy is not released to the body.

True

The free energy released by carbohydrate and protein in the body is similar.

True

This is probably a high ﬁgure; protein requirements increase with increasing
levels of energy expenditure.

225.

True

Most of it is incorporated into very low density lipoproteins(VLDL) and circulates
as such.

True

Its synthesis is determined mainly by saturated fat intake.

False

The main sources are egg yolk and animal fat.

False

It is eliminated mainly by excretion in the bile.

True

It is a precursor of a number of steroid hormones.

226.

True

Most are esteriﬁed to glycerol and cholesterol.

True

This is necessary for solubility.

False

They rise due to release from adipose tissue.

True

They are an important source of energy for contraction.

False

Glucose is the only normal substrate for energy production here.

227.

False

This is a vital solubilizing mechanism.

False

This favours formation of micelles.

False

Lecithin also contributes to the formation of micelles.

False

This can decrease the risk temporarily.

True

Excess bilirubin can give rise to pigment stones.

228.

False

Emptying is slowed as vagal coordination of gastric motility is lost.

True

This may compensate for the slowing effects of vagotomy.

True

Acid-pepsin can cause a jejunal stomal ulcer.

True

Rapid glucose absorption leads to excessive insulin secretion and a consequent
fall in blood glucose.

True

This is a further feature of the ‘dumping syndrome’. The sudden arrival of osmot-
ically active particles in the intestine draws extracellular fluid into the gut.

MCQ

Alimentary system – questions

Questions 229–234

229. Impaired intestinal absorption of

Iron occurs frequently following removal of most of the stomach.

Iodide leads to a reduction in size of the thyroid gland.

Water occurs in infants who cannot digest disaccharides.

Calcium may occur following removal of the terminal ileum.

Bile salts may occur following removal of the terminal ileum.

230. Peptic ulcer pain is typically relieved by

Raising the pH of the fluid bathing the ulcer.

Oral administration of sodium bicarbonate.

Oral administration of a non-absorbable antacid.

A drug which interferes with the action of acetylcholinesterase.

A drug which blocks the gastric proton pump.

231. Fat stores in the adult

Make up less than 5 per cent of average body weight.

Make up a smaller percentage of body weight in women than in men.

Release fatty acids when there is increased sympathetic nerve activity.

Release fatty acids when insulin is injected.

Enlarge by increasing the number of adipocytes they contain.

232. Metabolic rate can be estimated from measurements of

Total heat production.

The caloriﬁc value of the food consumed in the previous 24 hours.

Oxygen consumption provided the type of food being metabolized is known.

Oxygen consumption and the respiratory quotient.

Carbon dioxide production and the respiratory quotient.

233. Intestinal obstruction causes

Constipation.

Crampy pain due to intermittent vigorous peristalsis.

Distension due to fluid and gas proximal to the obstruction.

Hypotension.

Vomiting which is more severe with low than with high bowel obstruction.

234. The cause of jaundice is likely to be

Liver disease, if albumin is low and bilirubin mainly unconjugated.

Bile duct obstruction, if the urine is paler than normal.

Haemolysis, if the prothrombin level is below normal.

Haemolysis, if the urine is darker than normal.

A post-hepatic cause, if the bilirubin level in the blood is high.

MCQ

100

Alimentary system – answers

Answers

229.

True

Due to loss of gastric acid which reduces ferric to the ferrous iron, the form in
which it is absorbed. Another problem affecting iron absorption is rapid intesti-
nal transit.

False

The size increases to cause ‘goitre’ due to increased TSH stimulation.

True

The unabsorbed disaccharides such as lactose cause osmotic diarrhoea.

False

Calcium is absorbed mainly in the duodenum.

True

The terminal ileum is the main site of bile salt absorption.

230.

True

Acid is the cause of pain in these ulcers.

True

But this is absorbed and may cause alkalosis.

True

This also reduces acidity, but for a short time only.

False

This would increase vagal acid production.

True

This can give long lasting relief.

231.

False

The normal value is around 15–20 per cent.

False

Fat, as a percentage of body weight, is 5–10 per cent higher in women than in
men.

True

This is mediated via beta adrenergic receptor stimulation.

False

Insulin favours deposition of fat in the fat stores.

False

In obesity, adipocytes increase in size rather than number.

232.

True

Total energy expenditure must eventually appear as heat.

False

Energy production is related to the metabolism of food, not its intake.

True

Since oxygen is consumed only in metabolism, total oxygen consumption is an
index of metabolic rate; the energy produced per unit of oxygen consumed varies
somewhat with different substrates.

True

Respiratory quotient indicates the mix of substrates used.

True

Metabolic rate is proportional to carbon dioxide formation.

233.

True

This is complete when the bowel below the block is empty.

True

Intermittent colic is typical of early obstruction.

True

This may be severe when the obstruction is in the lower gut.

True

Due to hypovolaemia as secretions accumulate in the lumen of the intestines
above the obstruction.

False

Vomiting is worse with high obstruction since the copious upper alimentary
secretions cannot be absorbed from the intestines below the obstruction where
most absorption normally takes place.

234.

True

Both indicate impairment of liver function.

False

Urine is dark in jaundice due to bile duct obstructions since conjugated bilirubin
can pass the glomerular ﬁlter.

False

A low prothrombin suggests impaired liver function.

False

Haemolysis raises the level of unconjugated bilirubin which is protein-bound and
not excreted in the urine (acholuric jaundice).

False

It is high with all causes of jaundice.

MCQ

Alimentary system – questions

101

Questions 235–241

235. Complications that may arise after total gastrectomy include

Inadequate food intake.

Depletion of vitamin B

stores in the liver.

Malabsorption of fat due to rapid intestinal transit.

Impaired defaecation due to loss of the gastrocolic reflex.

Inability to digest protein.

236. Severe diarrhoea causes a decrease in

Body potassium.

Body sodium.

Extracellular fluid volume.

Total peripheral resistance.

Blood pH.

237. Diminished liver function may result in an increase in the

Albumin to globulin ratio in the blood.

Size of male breasts.

Level of unconjugated bilirubin in the blood.

Tendency to bleed.

Variability of the blood glucose level.

238. Peptic ulceration tends to heal after

Division of the vagal nerve supply to the stomach.

Surgical removal of the pyloric antrum.

Glucocorticoid drug treatment.

Elimination of the bacterium Helicobacter pylori from the stomach.

Treatment with histamine H

blocking drugs.

239. Urobilinogen is

A mixture of colourless compounds also known as stercobilinogen.

Formed in the reticuloendothelial system from bilirubin.

Converted into the dark pigment, urobilin, on exposure to air.

Absorbed from the intestine.

Excreted mainly in the urine.

240. Surgical removal of 90 per cent of the small intestine may cause a

decrease in

The fat content of the stools.

Bone mineralization (osteomalacia).

Extracellular fluid volume.

Blood haemoglobin level.

Body weight.

241. Lack of pancreatic juice in the duodenum may lead to

The presence of undigested meat ﬁbres in the stools.

An increase in the fat content of the faeces.

Faeces with a high speciﬁc gravity.

A tendency for the faeces to putrefy.

A high prothrombin level in blood.

MCQ

102

Alimentary system – answers

Answers

235.

True

Due to loss of the ‘reservoir’ function of the stomach.

True

Due to loss of gastric ‘intrinsic factor’, required for absorption of the vitamin.

True

The mechanism regulating food delivery to the small intestine is lost.

False

This ‘reflex’ is not essential for defaecation.

False

Pancreatic enzymes can make up for the loss of pepsin.

236.

True

Due to loss of secretions rich in potassium.

True

Sodium is the main cation lost in diarrhoea.

True

Body sodium is the ‘skeleton’ of extracellular fluid volume.

False

This is raised to maintain arterial blood pressure as plasma volume falls.

True

Loss of intestinal bicarbonate causes metabolic acidosis.

237.

False

Albumin, which is manufactured in the liver tends to fall relative to globulin in
plasma.

True

Due to loss of the liver’s ability to conjugate oestrogens and progestogens.

True

The liver normally conjugates bilirubin with glucuronic acid.

True

Due to reduced synthesis of clotting factors such as prothrombin by the liver.

True

Due to the liver’s reduced ability to store and mobilize glycogen.

238.

True

This reduces gastric acidity.

True

Gastrin which stimulates acid secretion is produced in the pyloric antrum.

False

Glucocorticoids by inhibiting tissue repair may make the ulceration worse.

True

This bacterium appears to play an important part in the pathogenesis of peptic
ulcers.

True

These reduce acidity and are widely used in the treatment of peptic ulceration.

239.

True

It is present in both urine and faeces.

False

It is formed in the intestine.

True

Urine rich in urobilinogen (due to haemolysis) darkens on exposure to light.

True

And carried back to the liver in the enterohepatic circulation.

False

It is excreted mainly in the bile.

240.

False

Fat absorption is incomplete and this causes steatorrhoea.

True

There is poor absorption of fat-soluble vitamin D.

False

Adequate salt and water absorption still occur.

True

Vitamin B

and iron absorption are impaired and this may cause anaemia.

True

Due to the malabsorption of food.

241.

True

Due to lack of the proteinases trypsin and chymotrypsin.

True

Due to impaired fat digestion and absorption caused by lack of pancreatic lipase.

False

A high fat content lowers speciﬁc gravity; stools may float.

True

Due to the high level of nutrients in the faeces, bacteria flourish.

False

It is reduced; malabsorption of fat reduces absorption of fat-soluble vitamin K
that is needed for prothrombin production.

MCQ

Alimentary system – questions

103

Questions 242–247

242. In liver failure there is likely to be

Salt and water retention.

Oedema in dependent extremities such as the feet and ankles.

Raised blood urea.

Impaired absorption of fat.

Intoxication after eating a high protein meal.

243. Gastric

Acid secretion in response to a lowered blood sugar is mediated by the hormone gastrin.

Emptying is facilitated by sympathetic nerve activity.

Acid secretion increases when histamine H

, muscarinic M

or gastrin receptors are acti-

vated.

Acid secretion is inhibited by the presence of food in the duodenum.

Contraction waves pass over the stomach at a rate of about ten per minute.

244. In portal hypertension

The total vascular resistance of the hepatic sinusoids is increased.

Portal blood flow through the liver is increased.

The volume of fluid in the peritoneal cavity increases.

A porto-caval shunt (anastomosis between portal vein and inferior vena cava) can
decrease the tendency to bleed into the alimentary tract.

A porto-caval shunt increases the risk of coma after bleeding into the alimentary tract.

245. Constipation is a recognized consequence of

Sensory denervation of the rectum.

Psychological stress.

Abnormality of the autonomic nerve supply to the colon.

A diet that leaves little unabsorbed residue in the gut.

Over-activity of the thyroid gland as in thyrotoxicosis.

246. Absorption of glucose by intestinal mucosal cells

Relies on a carrier mechanism in the cell membrane.

Is blocked by the same agents that block renal reabsorption of glucose.

Is enhanced by blockade of active sodium transport in the cells.

Involves the same carriers that are used for the absorption of galactose.

Takes place mainly in the ileum.

247. Vomiting

Is caused by violent rhythmic contractions of gut smooth muscle.

Is coordinated by a vomiting centre in the mid brain.

Of green fluid suggests that duodenal contents have regurgitated into the stomach.

May be accompanied by a fall in arterial blood pressure.

Is more marked in low intestinal obstruction than in high intestinal obstruction.

MCQ

104

Alimentary system – answers

Answers

242.

True

Due in part to the liver’s failure to conjugate salt-retaining hormones such as
aldosterone.

True

Due to the above plus depletion of plasma albumin.

False

It falls due to impaired urea synthesis from NH

⫹

released in deamination.

True

Due to impaired formation and excretion of bile salts.

True

Due to inadequate detoxiﬁcation of toxins derived from proteins in the diet.

243.

False

It is mediated through a vagal reflex and is absent in vagotomized stomachs.

False

This delays gastric emptying.

True

Histamine from mast-like cells activates H

receptors, acetylcholine from para-

sympathetic nerve endings activates M

receptors and gastrin activates gastrin

receptors.

True

The neural/hormonal mechanisms responsible for the inhibition are not certain.

False

The normal rate is around 3/minute.

244.

True

This is the cause of the hypertension.

False

It is decreased as blood is diverted to alternative routes back to the great veins.

True

Raised hydrostatic pressure increases ﬁltration from visceral capillaries; fluid
accumulates in the peritoneal cavity to cause ascites.

True

By diverting blood away from oesophageal varices.

True

The failure of the liver to detoxicate toxic end-products of protein metabolism in
liver failure can lead to hepatic encephalopathy; bypassing the liver with a porto-
caval shunt may aggravate the condition, especially after an intestinal bleed.

245.

True

This breaks the reflex arc on which defaecation depends.

True

Stress may modify the reflex to cause either constipation or diarrhoea.

True

In children this may cause megacolon.

True

Frequency of defaecation is related to the bulk of food residues.

False

This leads to increased frequency of defaecation.

246.

True

This facilitates transport from the lumen.

True

Phloridzin has this action; the carrier mechanisms at the two sites are similar.

False

It is impaired, suggesting that sodium absorption facilitates glucose absorption.

True

But different carriers are involved in fructose absorption.

False

It takes place mainly in the duodenum and jejunum.

247.

False

Forced expiratory efforts by skeletal muscles in the presence of a closed glottis
and pylorus are responsible for compressing the stomach.

False

It is coordinated by a vomiting centre in the medulla oblongata.

True

Bile pigments enter the gut in the duodenum.

True

This is one of several types of associated autonomic disturbance.

False

It is more marked in high obstruction because the copious digestive secretion
cannot be absorbed by the gut below the obstruction.

MCQ

Alimentary system – questions

105

Questions 248–249

248. Obesity

Is unlikely to occur on a high protein diet even if the caloriﬁc value of the food exceeds
daily energy expenditure.

Is associated with increased demands on pancreatic islet beta cells.

Can be assessed by multiple measurements of skin fold thickness.

Can be assessed by weighing the body in air and in water.

Is not diagnosed until body weight is 40 per cent above normal.

249. Muscle tone in the lower oesophagus is

Greater than tone in the middle oesophagus.

A major factor in preventing heartburn.

Increased in pregnancy.

Increased by gastrin.

Increased by anticholinergic drugs

MCQ

106

Alimentary system – answers

Answers

248.

False

If food energy intake exceeds energy expenditure, obesity develops regardless of
the predominant food in the diet.

True

Mild maturity-onset diabetes mellitus may be relieved by decreasing body weight.

True

Subcutaneous fat is a good indicator of the severity of obesity.

True

Body speciﬁc gravity which is inversely related to body fat content can be cal-
culated from these values.

False

The conventional threshold is 10 per cent.

249.

True

The high-pressure zone indicates the ‘cardiac sphincter’.

True

It prevents reflux of acid into the oesophagus.

False

It is decreased and heartburn is common in pregnancy.

True

This prevents reflux during gastric contractions.

False

These reduce tone, suggesting that cholinergic nerves have a role in maintaining
normal tone.

MCQ

ALIMENTARY SYSTEM

107

EMQs

Questions 250–260

EMQ Question 250

For each of the absorptive functions A–E, select the most appropriate absorption site from the
following list of alimentary tract sites.

1. Stomach.

2. Upper small intestine.

3. Lower small intestine.

4. Colon.

5. Rectum.

The site where most of the intestinal water is absorbed.

The site where most of the intestinal sodium is absorbed.

The main site of iron absorption.

The main site of Vitamin B

absorption.

The main site of bile salt absorption.

EMQ Question 251

For each of the digestive functions A–E, select the most appropriate digestive secretion from
the following list of secretions.

1. Salivary secretion.

2. Gastric secretion.

3. Pancreatic secretion.

4. Bile.

5. Intestinal secretion.

Splitting disaccharides.

Splitting triglycerides.

Absorption of vitamin B

Emulsiﬁcation of fat.

Digestion of nucleic acids.

EMQ Question 252

For each of the examples of intestinal motility A–E, select the most appropriate stimulus from
the following list of stimuli:

1. Release of CCK-PZ.

2. Distension of the viscus wall.

3. Release of secretin.

4. Release of gastrin.

5. Sympathetic nerve activity.

Gastro-colic reflex.

Receptive relaxation.

Peristalsis.

Contraction of the cardiac (oesophogeal-gastric) sphincter.

Contraction of the gallbladder.

EMQ

108

Alimentary system – answers

Answers for 250

Option 2

Upper small intestine. About four ﬁfths of intestinal water is absorbed by

the osmotic gradient created by glucose and sodium absorption in the small intestine, the
remaining ﬁfth is absorbed in the colon.

Option 2

Upper small intestine. Most sodium is absorbed by active transport in the

upper small intestine but some is also absorbed in the lower small intestine and in the
colon.

Option 2

Upper small intestine. Iron is absorbed in the ferrous state using an intra-

cellular iron carrier mainly in the upper small intestine but some is also absorbed in the
lower small intestine.

Option 3

Lower small intestine. Vitamin B

is absorbed complexed with intrinsic

factor in the terminal ileum.

Option 3

Lower small intestine. Like Vitamin B

, bile salts are reabsorbed in the lower

small intestine to be returned to the liver as part of the enterohepatic circulation.

Answers for 251

Option 5

Intestinal secretion. Intestinal juice contains the enzymes maltase, lactase

and sucrase that split maltose, lactose and sucrose respectively.

Option 3

Pancreatic secretion. Pancreatic lipase splits neutral fat into glycerol and

fatty acids.

Option 2

Gastric secretion. Gastric juice contains the intrinsic factor needed for the

absorption of Vitamin B

Option 4

Bile. Bile salts help to emulsify fat so that the fat droplets offer a large sur-

face area to the action of lipases.

Option 3

Pancreatic secretion. Nucleic acids are split by pancreatic nucleases in the

small intestine.

Answers for 252

Option 2

Distension of the viscus wall. For this reflex, the distension of the stomach

wall following ingestion of a meal is thought to stimulate colonic motility that results in
defaecation.

Option 2

Distension of the viscus wall. When food is ingested, the smooth muscle in

the stomach wall relaxes so that the added bulk can be accommodated without much
increase in intragastric pressure.

Option 2

Distension of the viscus wall. When a bolus of food distends a hollow viscus

it sets up a wave of contraction preceded by a wave of relaxation that carries the bolus
along the viscus. Though peristalsis can be modiﬁed by autonomic nerves, the mechanism
is based on local nerve networks in the wall of the viscus.

Option 4

Release of gastrin. Gastrin secreted in response to a meal increases tone in

the cardiac sphincter and so prevents regurgitation of gastric contents into the oesopha-
gus during stomach contractions.

Option 5

Release of CCK-PZ. CCK-PZ released from the bowel wall when fat enters

the duodenum causes the gall bladder to contract to empty its contents into the second
part of the duodenum. It also inhibits gastric emptying.

EMQ

Alimentary system – questions

109

EMQ Question 253

For each of the structures and substances found in the alimentary tract A–E, select the most
appropriate function from the list below.

1. Fat transport.

2. Secrete alkaline mucus.

3. Activates enzymes in pancreatic

4. Secrete serotonin.

secretion.

5. Ingest bacteria.

Enterochromafﬁn cells.

Brunner’s glands.

Micelles.

Kupffer cells.

Enterokinase.

EMQ Question 254

For each of the digestive functions A–E, select the most appropriate digestive enzymes from
the following list of enzymes.

1. Rennin.

2. Endopeptidases.

3. Sucrase.

4. Alpha-amylase.

5. Deoxyribonuclease.

Acts on protein to produce polypeptides and amino acids.

Acts on DNA to produce nucleotides.

Acts on a disaccharide to produce fructose and glucose.

Acts on starch to produce dextrins and maltose.

Acts on milk to produce a clot.

EMQ Question 255

For each of the absorptive functions A–E, select the most appropriate co-factor(s) required for
absorption from the list below.

1. A sodium dependent carrier system.

2. Apoferritin.

3. Vitamin D.

4. Intrinsic factor.

5. Bile salts.

Fat absorption.

Iron absorption.

Glucose absorption.

Calcium absorption.

Vitamin B

absorption.

EMQ

110

Alimentary system – answers

Answers for 253

Option 4.

Secrete serotonin. Certain duodenal cells called enterochromafﬁn cells con-

tain serotonin and the polypeptide ‘motilin’ that are thought to influence smooth muscle
motility in the gut.

Option 2

Secrete alkaline mucus. Brunner’s glands in the duodenum secrete a thick

alkaline mucus that protects the duodenal mucosa against acid when gastric juice enters
the duodenum.

Option 1

Fat transport. Micelles are complexes of lipids and bile salts. The complexes

are water-soluble and this aids their take up by the enterocytes lining the intestinal
mucosa.

Option 5

Ingest bacteria. Kupffer cells are macrophages in the capillary sinusoids of

the liver; when they are deﬁcient due to liver disease there is increased risk of organisms
passing from the gut to the systemic circulation via the portal circulation.

Option 3

Activates enzymes in pancreatic secretion. Trypsinogen is a proenzyme

secreted by the pancreas that is activated in the lumen of the small intestine by the
enzyme enterokinase secreted by the intestinal mucosa.

Answers for 254

Option 2

Endopeptidases. Secreted by the pancreas in an inactive form, the endo-

peptidases that include trypsin, chymotrypsin and elastase split the peptide bonds in poly-
peptides.

Option 5

Deoxyribonuclease. RNA is split by ribonuclease.

Option 3

Sucrase. Two other disaccharidases present in intestinal secretions, lactase

and maltase, split lactose and maltose into galactose and glucose and glucose and glucose
respectively.

Option 4

Alpha-amylase. Alpha amylase is produced by the salivary glands as well as

by the pancreas.

Option 1

Rennin. Found in the gastric juice of infants, rennin aids in milk digestion

by causing it to clot and slow its passage out of the stomach.

Answers for 255

Option 5

Bile salts. Bile salts aid fat absorption by helping to emulsify the fat into

very small globules which present a large surface area that can be attacked by pancreatic
lipase. They then form part of the micelles that ﬁt neatly between the microvilli of the
enterocytes.

Option 2

Apoferritin. Apoferritin is an intracellular carrier that carries the iron mole-

cules from the mucosal surface of the enterocytes to the inner surface where it is deliv-
ered to the carrier molecule, transferrin, in the plasma.

Option 1

A sodium dependent carrier system. The co-transporter molecule for glucose

is called SGLT (sodium dependent glucose transporter).

Option 3

Vitamin D. In Vitamin D deﬁciency, calcium is not taken up by the intesti-

nal mucosa. This results in weakening of the bones as in rickets and osteomalacia.

Option 4

Intrinsic factor. Vitamin B

has to be complexed with intrinsic factor in

gastric juice before it can be absorbed from the gut.

EMQ

Alimentary system – questions

111

EMQ Question 256

For each of the deﬁciencies of digestive secretions A–E, select the most appropriate conse-
quence from the list below.

1. Pale stools.

2. Local infections.

3. Steatorrhoea.

4. Milk intolerance.

5. Anaemia.

Saliva deﬁciency.

Biliary obstruction.

Lactase deﬁciency.

Pancreatic juice deﬁciency.

Gastric juice deﬁciency.

EMQ Question 257

For each of the factors affecting intestinal activity A–E, select the most appropriate response
from the list below.

1. Inhibition of gastric secretion.

2. Stimulation of gastric secretion.

3. Increase in gastric motility.

4. Decrease in gastric motility.

5. Gall bladder contraction.

CCK-PZ.

Fat in the duodenum.

Pentagastrin.

Blockade of H

receptors.

Adrenaline injection.

EMQ Question 258

For each of the structures in the alimentary tract A–E, select the most appropriate option from
the list below.

1. Controls entry of bile into the

2. Fat absorption.

intestine.

3. Glucose absorption.

4. Secretion of gastric acid.

5. Lymphoid aggregations in the intestines

involved with immunity.

Intestinal structures

Lacteals.

Brush border.

Oxyntic cells.

Sphincter of Oddi.

Peyer’s patches.

EMQ

112

Alimentary system – answers

Answers to 256

Option 2

Local infections. The flow of saliva helps to control the multiplication of

bacteria in the mouth.

Option 1

Pale stools. Bile entering the alimentary tract is responsible for the normal

brown colour of the stools.

Option 4

Milk intolerance. Lactase deﬁciency is seen in a proportion of the popula-

tion. There is an inability to digest and absorb milk sugar. This results in an osmotic diar-
rhoea that can be a problem especially in babies where milk forms a large part of the
dietary intake.

Option 3

Steatorrhoea. Steatorrhoea, the presence of unsplit fat in the faeces, is seen

in the absence of pancreatic juice since dietary fat cannot be hydrolysed and consequently
cannot be absorbed.

Option 5

Anaemia. A macrocytic anaemia develops because there is no intrinsic

factor to facilitate the absorption of Vitamin B

Answers for 257

Option 5

Gallbladder contraction. CCK, produced by the mucosal cells in the duodenal

wall when fat or other nutrients enter that part of the gut, travels in the blood to the gall
bladder so that the bile contents are sent to the duodenum to help in the digestion and
absorption of fat.

Option 4

Decrease in gastric motility. Fat in the duodenum slows the transit of gas-

tric contents into the small gut and so slows and delays the digestion of the gastric con-
tents.

Option 2

Stimulation of gastric secretion. Pentagastrin is a pharmacological product

containing ﬁve of the amino acids in gastrin that can act like gastrin to stimulate gastric
secretion. It is used to test the functional efﬁciency of the gastric mucosa to secrete gas-
tric juice.

Option 1

Inhibition of gastric secretion. Histamine is the neurotransmitter at vagal

nerve endings in the stomach and acts on H

receptors. Thus H

receptor blockers can

reduce acid secretion by the gastric mucosa.

Option 4

Decrease in gastric motility. Adrenaline and similar adrenergic agents cause

intestinal smooth muscle to relax.

Answers for 258

Option 2

Fat absorption. Most of the absorbed fat is taken up directly by lacteals, so

called for their white colour following a fatty meal due to the fat globules in the lymph.

Option 3

Glucose absorption. The brush border that is characteristic of the luminal

surface of enterocytes is made up of tiny microvilli protruding into the lumen of the gut
and offering a huge surface area for absorption of the products of digestion.

Option 4

Secretion of gastric acid. These cells, sometimes also called parietal cells, are

found in the mucosa of the body and fundus of the stomach and are responsible for HCl
secretion.

Option 1

Controls entry of bile into the intestine. The sphincter of Oddi lies in the

second part of the duodenum where the bile duct and the pancreatic ducts meet and con-
trols the flow of bile and pancreatic secretions into the duodenum.

Option 5

Lymphoid aggregations in the intestines involved with immunity. These

patches are composed of lymphoid tissue and are responsible for immune reactions and
responses in the gut.

EMQ

Alimentary system – questions

113

EMQ Question 259

For each of the surgical interventions (-ectomy means removal) carried out on the alimentary
tract A–E, select the most appropriate possible consequence from the list below.

1. No digestive consequences.

2. Bulky liquid stools.

3. Dumping syndrome.

4. Steatorrhoea.

5. Indigestion after fatty meals.

Gastrectomy.

Pancreatectomy.

Colectomy.

Cholecystectomy.

Appendicectomy.

EMQ Question 260

For each of polypeptides secreted by the enteric nervous system in the alimentary tract A–E,
select the most appropriate effect on the gut from the list below.

1. Release of gastrin.

2. Relaxation of sphincters.

3. Increase in small intestinal motility.

4. Inhibition of gut motility.

5. Inhibition of gastric emptying.

VIP.

CCK-PZ.

Somatostatin.

Substance P.

GRP.

EMQ

114

Alimentary system – answers

Answers for 259

Option 3

Dumping syndrome. When the stomach is removed, ingested food passes

very rapidly to the small intestine and can lead to the unpleasant consequences of fluid
loss to the intestinal lumen and excessive insulin secretion. The syndrome is called the
‘dumping syndrome’.

Option 4

Steatorrhoea. This may be seen following pancreatectomy because lack of

lipase allows undigested fat to appear in the faeces.

Option 2

Bulky liquid stools. Removal of the colon limits the ability of the alimentary

tract to reabsorb water and this results in the passage of watery stools.

Option 5

Indigestion after fatty meals. The loss of the gall bladder’s ability to send bile

to the duodenum after a fatty meal results in poor digestion and absorption of the meal
and hence abdominal discomfort.

Option 1

No digestive consequences. The appendix has no known function other than

as a lymphoid organ and its immune function can be taken over by other lymphoid tissue
in the intestines.

Answers for 260

Option 2

Relaxation of sphincters. Vasoactive intestinal polypeptide (VIP) also causes

vasodilatation by relaxing vascular smooth muscle.

Option 5

Inhibition of gastric emptying. Besides its main action of stimulating the gall

bladder to contract, cholecystokinin (CCK) decreases the rate of emptying of the stomach.

Option 4

Inhibition of gut motility. Somatostatin, the growth hormone-inhibiting hor-

mone, originally isolated in the hypothalamus, is secreted by D cells in the intestinal
mucosa. It inhibits the release of several gut hormones including motilin and so inhibits
gut motility.

Option 3

Increase in small intestinal motility. Substance P, a polypeptide found in

intestinal mucosal endocrine cells, acts locally to increase gut motility.

Option 1

Release of gastrin. Gastrin-releasing polypeptide (GRP) is released by the

postganglionic vagal ﬁbres that innervate the G cells in the lateral walls of the glands in
the pyloric antrum. Activity in these nerves causes release of the gastrin granules in the
G cells.

EMQ

NEUROMUSCULAR SYSTEM

115

MCQs

Questions 261–266

261. A reflex action

Is initiated at a sensory receptor organ.

May result in endocrine secretion.

Involves transmission across at least two central nervous synapses in series.

May be excitatory or inhibitory.

Is independent of higher centres in the brain.

262. In skeletal muscle neuromuscular junctions

The motor end plate is the motor nerve terminal.

Spontaneous (miniature) potentials may be recorded in the motor nerve terminal.

Motor nerve terminals have vesicles containing acetylcholine.

There is a high concentration of acetylcholinesterase.

Transmission is facilitated by botulinum toxin.

263. Cerebrospinal fluid

Is formed in the arachnoid granulations.

Provides the brain with most of its nutrition.

Protects the brain from injury when the head is moved.

Has a lower pressure than that in the cerebral venous sinuses.

Flow around the adult brain is around half a litre per day.

264. A skeletal muscle fibre

Membrane is negatively charged on the inside with respect to the outside at rest.

Contains intracellular stores of calcium ions.

Is normally innervated by more than one motor neurone.

Becomes more excitable as its resting membrane potential falls.

Becomes less excitable as the extracellular ionized calcium levels fall.

265. In sensory receptors

Stimulus energy is converted into a local depolarization.

The generator potential is graded and self-propagating.

A generator potential can be produced by only one form of energy.

The frequency of action potentials generated doubles when the strength of the stimulus
doubles.

Serving touch sensation, constant suprathreshold stimulation causes action potentials to
be generated at a constant rate.

266. A somatic lower motor neurone

Innervates fewer ﬁbres in an eye muscle than does one innervating a leg muscle.

Conducts impulses at a speed similar to that in an autonomic postganglionic neurone.

Is unmyelinated.

Conducts impulses which cause relaxation in some skeletal muscles.

Synapse with skeletal muscle but not with other neurones.

MCQ

116

Neuromuscular system – answers

Answers

261.

True

Stimulation of the receptor generates impulses in the afferent limb.

True

Stimulation of osmoreceptors reflexly modiﬁes ADH output from the posterior
pituitary gland.

False

The knee jerk reflex arc contains only one central nervous synapse.

True

In the knee jerk extensors of the knee contract, while flexors relax (reciprocal
inhibition).

False

Higher centres can facilitate or inhibit many reflex actions such as micturition.

262.

False

It is the modiﬁed muscle membrane adjacent to the nerve terminal.

False

They may be recorded at the motor end plate.

True

This neurotransmitter, released by exocytosis, excites the end plate membrane.

True

This makes acetylcholine’s action transient.

False

Botulinum toxin blocks transmission by an action on the motor nerve terminals.

263.

False

It is formed in choroid plexuses by active and passive processes.

False

Most of the brain’s nutrition comes from the blood.

True

This is its main function and it does so through cushioning and buoyancy.

False

Its higher pressure allows drainage by ﬁltration to the dural venous sinuses via
the arachnoid villi.

True

This is about four times its volume.

264.

True

This ‘resting membrane potential’ is about

⫺90 mV.

True

These are released on excitation.

False

A single neurone supplies a group of muscle ﬁbres.

True

It becomes more excitable as its membrane potential approaches the ﬁring
threshold (about

⫺70 mV).

False

Decreasing extracellular Ca

⫹

increases excitability and may lead to spontaneous

contractions (tetany), possibly by increasing sodium permeability.

265.

True

This is the generator potential.

False

It is graded but not propagated.

False

But sensitivity is greatest to one form of energy – the ‘adequate stimulus’.

False

Frequency is related to the logarithm of the strength of the stimulus.

False

Frequency falls with time due to adaptation.

266.

True

The more precise the movement required, the fewer the ﬁbres supplied by one
motor neurone.

False

Somatic motor neurones conduct at 60–120 m/sec; autonomic at about 1 m/sec.

False

Fast-conducting ﬁbres are large and myelinated.

False

Impulses carried by somatic motor neurones are excitatory to skeletal muscle.

False

Some carry impulses to inhibitory (Renshaw) cells in the anterior horn.

MCQ

Neuromuscular system – questions

117

Questions 267–272

267 Impulses serving pain sensation in the left foot are relayed

Across synapses in the left posterior root ganglion.

By ﬁbres in the left spinothalamic tract.

By the same spinal cord tract which serves heat and cold sensation.

To the thalamus on the right side.

To the cerebral cortex before entering consciousness.

268. An excitatory post-synaptic potential

Is the depolarization of a post-synaptic nerve cell membrane that occurs when a pre-
synaptic neurone is stimulated.

Involves reversal of polarity across the post-synaptic nerve cell membrane.

May be recorded from a posterior root ganglion cell.

Is propagated at the same rate as an action potential.

Is caused by the electrical ﬁeld induced by activity in the pre-synaptic nerve terminals.

269. The ascending reticular formation

When stimulated tends to increase alertness.

Transmits impulses to higher centres via a multisynaptic pathway.

Is activated by collateral branches of sensory neurones.

Neurones project to most parts of the cerebral cortex.

Increases its activity during deep sleep.

270. The cerebellum

Modiﬁes the discharge of spinal motor neurones.

Is essential for ﬁnely coordinated movements.

Has an afferent input from the motor cortex.

Has an afferent input from muscle proprioceptors.

Has an afferent input from the vestibular system.

271. During deep sleep there is a fall in

Hand skin temperature.

Arterial P

Blood growth hormone/cortisol ratio.

Metabolic rate.

Urine formation.

272. Sympathetic

Ganglionic transmission is mediated by acetylcholine.

Neuromuscular transmission at the heart is mediated by adrenaline.

Neuromuscular transmission in hand skin arterioles is mediated by acetylcholine.

Neuroglandular transmission at sweat glands is mediated by noradrenaline.

Neuromuscular transmission at the iris is mediated by noradrenaline.

MCQ

118

Neuromuscular system – answers

Answers

267.

False

The ganglion contains sensory cell bodies but no synapses; primary pain ﬁbres
carrying these impulses synapse with secondary neurones in the left posterior
horn.

False

They cross to the right spinothalamic tract.

True

Pain and temperature ﬁbres travel together.

True

Sensations other than smell are relayed in the thalamus.

False

They enter consciousness at a subcortical level.

268.

True

An inhibitory potential is a hyperpolarization.

False

It is a transient (about 5 msec), small (about 5 mV) depolarization towards the
threshold for ﬁring.

False

It may be recorded from a motor neurone.

False

It is not propagated.

False

It is caused by transmitters changing permeability in post-synaptic membranes.

269.

True

Associated with increased electrical activity in cortical regions.

True

Diffuse cortical activity following sensory stimulation occurs later than local
postcentral gyrus activity.

True

Sensory ﬁbres ascending to the thalamus send collaterals to reticular nuclei.

True

The diffuse cortical activity following sensory stimulation is abolished by damage
to the reticular formation.

False

Decreased activity leads to a higher arousal threshold during sleep.

270.

True

Hence it influences skeletal muscle activity.

True

Damage to it leads to movements being clumsy (ataxia).

True

This provides information of the desired movement.

True

This provides information of the actual movement.

True

It has an important role in maintaining balance.

271.

False

Skin temperature rises due to vasodilation.

False

The level rises due to hypoventilation.

False

Growth hormone level is higher, cortisol lower in sleep.

True

Due to slowing of metabolism and a fall in catecholamine level.

True

The antidiuretic hormone level is higher in sleep.

272.

True

This applies to parasympathetic ganglia also.

False

The transmitter is noradrenaline.

False

The transmitter is noradrenaline here also.

False

These sympathetic ﬁbres are cholinergic.

True

Sympathetic adrenergic ﬁbres innervate radial muscle in the iris; cholinergic
parasympathetic ﬁbres innervate the circular muscle.

MCQ

Neuromuscular system – questions

119

Questions 273–278

273. The blood–brain barrier

Slows equilibration of solutes between blood and brain tissue fluids.

Is a more effective barrier for fat-soluble substances than water-soluble substances.

Is a more effective barrier in infants than in adults.

Is a more effective barrier for CO

than for O

Permits hydrogen ions to pass freely.

274. Nerve impulses

Can travel in one direction only in a nerve ﬁbre.

Can travel in one direction only across a synapse.

Travel at the speed of an electric current.

Correspond in duration to that of the nerve refractory period.

Can be transmitted at higher frequencies in autonomic than in somatic nerves.

275. In skeletal muscle

Contraction occurs when its pacemaker cells depolarize sufﬁciently to reach the thresh-
old for ﬁring.

Calcium is taken up by the sarcotubular system when it contracts.

Actin and myosin ﬁlaments shorten when it contracts.

The sarcomeres shorten during contraction.

Contraction strength is related to initial length of the muscle ﬁbres.

276. The electroencephalogram normally shows voltage waves

Whose amplitude is related to intelligence.

Of smaller amplitude during deep sleep than during alert wakefulness.

Of lower frequency during deep sleep than during alert wakefulness.

Of greater amplitude than those of the electrocardiogram.

Which are bilaterally symmetrical.

277. Saltatory conduction

Occurs only in myelinated ﬁbres.

Does not depend on depolarization of the nerve membrane.

Has a slower velocity in cold than in warm conditions.

Is faster than non-saltatory conduction in nerve ﬁbres with diameters around 10

␮m.

Transmits impulses with a velocity proportional to ﬁbre diameter.

278. Parasympathetic nerves

Have opposite effects to sympathetic nerves on intestinal smooth muscle.

Have opposite effects to sympathetic nerves on iris smooth muscle.

Cause vasodilatation in skeletal muscle during prolonged exercise.

Cause sweat secretion in skin when body temperature rises.

Have longer postganglionic than preganglionic ﬁbres.

MCQ

120

Neuromuscular system – answers

Answers

273.

True

Capillary permeability is lower in the brain than in other tissues.

False

Fat-soluble substances cross readily due to the lipid in cell membranes.

False

The reverse is true; bilirubin, which cannot pass in the adult, does so in infants.

False

Both CO

and O

cross the blood–brain barrier easily.

False

This protects brain tissues against sudden changes in the pH of blood.

274.

False

In axons, impulses travel in both directions from a point of electrical stimulation.

True

The transmitter vesicles are in the pre-synaptic terminal.

False

Impulse propagation is a different process and much slower than electrical cur-
rent.

True

Nerves cannot be re-excited while their membrane polarity is reversed.

False

The shorter refractory periods in somatic nerves allow higher frequencies.

275.

False

Skeletal muscle has no pacemaker cells and shows no spontaneous activity.

False

Calcium is released from intracellular stores when it contracts.

False

The ﬁlaments do not shorten but slide together over one another.

True

There is greater overlap of the actin and myosin ﬁbrils.

True

Moderate stretch increases contraction strength as in the heart.

276.

False

EEG is no index of intelligence.

False

High amplitude waves occur in deep sleep; the reverse is true of wakefulness.

True

The high amplitude waves in sleep are of low frequency; the reverse is true of the
low amplitude waves in wakefulness.

False

EEG voltages are much smaller than ECG voltages.

True

Asymmetry is a sign of disease.

277.

True

Excitation leaps from node to node across the myelinated segments.

False

The membrane does depolarize at the nodes.

True

Cooling slows sodium conductance at the nodes.

True

Theoretically, saltatory conduction becomes the slower in nerve ﬁbres with dia-
meters less than 1

␮m.

True

And to the distance between nodes.

278.

True

Parasympathetic nerves stimulate, and sympathetic nerves inhibit, intestinal
smooth muscle contractions.

False

Both contract iris smooth muscle; however parasympathetics constrict the pupil
by contracting circular muscle, sympathetics dilate it by contracting radial
muscle.

False

Skeletal muscle has no parasympathetic nerve supply; local metabolites are
responsible for the vasodilatation.

False

Skin has no parasympathetic innervation; sympathetic cholinergic nerves are
responsible for the increase in sweating when body temperature rises.

False

The reverse is the case.

MCQ

Neuromuscular system – questions

121

Questions 279–284

279.

␣ (alpha) adrenoceptors

Are located on myoﬁlaments in smooth muscle cells.

Are distinguishable from

␤ (beta) receptors using electron microscopy.

Can be stimulated by both adrenaline and noradrenaline.

Are involved in the vasoconstrictor responses in skin to adrenaline.

Are involved in the heart rate responses to noradrenaline.

280. Neurones serving conscious muscle proprioception

Conduct impulses at a similar rate to somatic motor neurones.

Have their cell bodies in the ipsilateral posterior horn of the spinal cord.

Use a different pathway from the primary neurones serving unconscious proprioception.

Synapse with secondary neurones whose axons project up the ipsilateral posterior
(dorsal) columns of the spinal cord.

Synapse with neurones which cross the midline of the body in the brainstem.

281. The

␣ (alpha) rhythm of the electroencephalogram

Disappears when the eyes are closed.

Is an electrical potential with an amplitude around one millivolt.

Has a frequency of 8–12 Hz.

Has a lower frequency than the

␦ (delta) rhythm.

Indicates that the subject is awake.

282. Nerve fibres continue to conduct impulses when

Extracellular sodium is replaced by potassium.

Extracellular sodium is replaced by a non-diffusible cation.

Temperature is lowered from 37 to 30

Temperature is lowered to below 0

C provided freezing does not occur.

The sodium-potassium pump is inactivated.

283. The primary sensory ending of a muscle spindle is stimulated by

Shortening of an antagonist muscle.

Relaxation of the muscle concerned when under load.

Shortening of the extrafusal ﬁbres.

Stimulation of the gamma efferent ﬁbres.

Striking the appropriate tendon with a tendon hammer.

284. In the spinal cord

Pain impulse trafﬁc may be modulated in the posterior horn.

Autonomic motor neurones arise in the lateral horn.

Gamma-aminobutyric acid may act as an excitatory neurotransmitter.

Reflex centres are normally inhibited by descending impulses from supra-spinal centres.

Post-synaptic excitation may be mediated by amino acid derivatives acting as neuro-
transmitters.

MCQ

122

Neuromuscular system – answers

Answers

279.

False

They are located in the cell membranes.

False

They cannot be visualized; chemical evidence suggests their structure is similar.

True

Also by drugs such as ephedrine which has a similar structure.

True

Alpha receptors predominate in skin arterioles.

False

Cardiac adrenoceptors are predominantly beta receptors.

280.

True

Both are fast ﬁbres and reflexes involving them have a short reflex delay.

False

They are in the posterior root ganglion.

True

Unconscious proprioception impulses travel in the spino-cerebellar tracts.

False

The primary neurone axons pass up the ipsilateral posterior columns before syn-
apsing with secondary neurones at the top of the spinal cord.

True

The secondary neurones cross in the medulla oblongata.

281.

False

It is best seen when the subject’s eyes are closed.

False

It is much smaller, at around 50 microvolts.

True

It is described in terms of frequency and amplitude.

False

The upper limit of the delta rhythm is 3.5 Hz.

True

It disappears with the onset of sleep.

282.

False

This would depolarize the ﬁbres completely.

False

Influx of cations is essential for depolarization.

True

However, conduction is slowed.

False

Nerve ﬁbres stop conducting before tissue freezing occurs.

True

They continue to conduct until the electrochemical gradients created by the pump
decline.

283.

True

This stretches the agonist and its spindles.

True

This also stretches the spindles.

False

This reduces the stretch of the spindle.

True

Muscle contraction at each end of the spindle stretches the nuclear bag.

True

The knee jerk is initiated by striking the patellar tendon which stretches spindles
in the quadriceps muscle.

284.

True

In the substantia gelatinosa; endorphins may inhibit pain impulse transmission.

True

These are the preganglionic autonomic motor neurones.

False

It is an inhibitory transmitter thought to be responsible for IPSPs at post-synaptic
membranes.

False

Loss of supraspinal facilitation is responsible for the areflexia in spinal shock.

True

Glutamate and aspartate are thought to be responsible for much of excitatory
transmission in the CNS.

MCQ

Neuromuscular system – questions

123

Questions 285–289

285. In the cerebral cortex

Neuronal connections are innate and immutable.

Language and non-language skills are represented in different hemispheres.

The areas concerned with emotional behaviour are concentrated in the frontal lobes.

The cortical area devoted to sensation in the hand is larger than that for the trunk.

Stimulation of the motor cortex causes contractions of individual muscles on the oppo-
site side of the body.

286. When a nerve cell membrane is depolarized by 5 mV

Its permeability to sodium increases.

Sodium ions move into the cell to cause further depolarization.

Potassium ions move outwards down their electrochemical gradient.

Chloride ions move inwards down their electrochemical gradient.

An action potential is generated.

287. Generalized sympathetic activity is characterized by

Contraction of the radial muscle in the iris.

Increased urinary excretion of catecholamines.

Lipolysis in adipose tissue.

Decreased conduction rate in the atrio-ventricular bundle.

Relaxation of sphincteric smooth muscle in the alimentary tract.

288 Stimulation of the vagus nerves causes

A reduction in the strength of ventricular contraction.

Secretion and vasodilatation in the salivary glands.

Mucous secretion from bronchial mucosal cells.

The spleen to contract.

The gallbladder to contract.

289. An action potential in a nerve fibre

Occurs when its membrane potential is hyperpolarized to a critical level.

Is associated with a transient increase in membrane permeability to sodium.

Is associated with a transient decrease in membrane permeability to potassium.

Induces local electrical currents in adjacent segments of the ﬁbre.

Has an amplitude which varies directly with the strength of stimulus.

MCQ

124

Neuromuscular system – answers

Answers

285.

False

The connections of brain neurones can be changed fairly rapidly to reflect new
patterns of activity and sensory experience; this is referred to as neuronal plas-
ticity.

True

The left hemisphere is dominant for speech in most people and the right is dom-
inant for skills requiring appreciation of time and space relationships.

False

They are found mainly in the limbic cortex.

True

The cortical area given to a particular skin area is related to the richness of its
sensory innervation, not its anatomic size.

False

Stimulation causes integrated movements not individual muscle contractions.

286.

True

Depolarization opens sodium channels in the membrane.

True

Positively charged sodium ions move down their electrochemical gradient
making the inside of the ﬁbre more positive.

True

The fall in membrane potential increases the outward electrochemical gradient
for the positively charged potassium ions; their exit tends to stabilize the mem-
brane potential.

True

The fall in membrane potential increases the inward electrochemical gradient for
chloride; this again tends to restore the resting membrane potential.

False

Not unless it reaches the threshold for ﬁring.

287.

True

This dilates the pupil.

True

Derived from activity in the adrenal medulla and sympathetic nerve endings.

True

This provides fatty acids for energy production.

False

It increases and the PR interval shortens; higher heart rates are made possible.

False

Sympathetic activity inhibits most smooth muscle in gut but contracts the
sphincters.

288.

False

Ventricles have little vagal innervation.

False

The vagus does not supply parasympathetic nerves to the salivary glands.

True

It also contracts bronchial smooth muscle.

False

It is sympathetic activity that causes the spleen to contract.

True

This together with relaxation of the sphincter of Oddi drives bile into the duo-
denum.

289.

False

It occurs when the membrane potential is reduced to its threshold for ﬁring.

True

This leads to rapid depolarization towards the sodium equilibrium potential.

False

Permeability to K

⫹

increases and the resulting K

⫹

efflux contributes to membrane

repolarization.

True

This depolarizes the adjacent axon and leads to propagation of the impulse.

False

Because of the ‘all or none’ law, impulse conﬁguration is independent of stimu-
lus strength.

MCQ

Neuromuscular system – questions

125

Questions 290–294

290. Non-myelinated axons differ from myelinated axons in that they are

Not sheathed in Schwann cells.

Not capable of regeneration after section.

Found only in the autonomic nervous system.

Less excitable.

Refractory for a longer period after excitation.

291. Resting nerve cell membranes are more permeable to

Organic anions than to Cl

⫺

anions.

⫹

ions than to Cl

⫺

ions.

⫹

ions than to K

⫹

ions.

Oxygen molecules than to glucose molecules.

Water molecules than to H

⫹

ions.

292. Acetylcholine

Acts on the same type of receptor on postganglionic ﬁbres in sympathetic and parasym-
pathetic ganglia.

Acts on the same type of receptor on target organs at cholinergic sympathetic and para-
sympathetic nerve terminals.

Acts on the same type of receptor at autonomic ganglia and at somatic neuromuscular
junctions.

Acts as an excitatory transmitter in the basal ganglia.

In blood is hydrolyzed by the same cholinesterase as is found at neuromuscular junc-
tions.

293. Visceral smooth muscle differs from skeletal muscle in that

It contracts when stretched.

It is not paralyzed when its motor nerve supply is cut.

Its cells have unstable resting membrane potentials.

It contains no actin or myosin.

Excitation depends more on influx of extracellular calcium than release of calcium from
endoplasmic reticulum.

294. An inhibitory post-synaptic potential

May be recorded in a post-ganglionic sympathetic neurone.

May be recorded in an anterior horn motor neurone.

Does not exceed one millivolt in amplitude.

Moves membrane potential towards the equilibrium potential for potassium.

May summate in space and time with other excitatory and inhibitory potentials in the
same neurone.

MCQ

126

Neuromuscular system – answers

Answers

290.

False

Both types have Schwann cell sheaths.

False

Following section, the central end of the axon buds and grows down the
Schwann cell sheath until it reaches its target organ.

False

Some sensory ﬁbres serving pain and temperature are unmyelinated C ﬁbres.

True

Myelinated ﬁbres have a lower threshold for stimulation.

True

2 ms compared with 0.5 ms in well myelinated nerves; myelinated ﬁbres can
transmit impulses at higher frequencies than unmyelinated nerves.

291.

False

Organic anions cannot cross the membrane readily.

False

The permeability to Cl

⫺

is about twice that to K

⫹

False

⫹

permeability is about 100 times that of Na

⫹

True

, being a small, nonpolar, lipophilic molecule dissolves in the membrane lipid

and crosses more easily than the larger glucose molecule.

True

The bilipid layer is more permeable to water than to the charged hydrogen ion.

292.

True

These are ‘nicotinic’ receptors and the action is blocked at both sites by drugs
such as hexamethonium.

True

These are ‘muscarinic’ receptors and the action is blocked at both sites by atro-
pine.

False

The receptors are different; curare blocks transmission at somatic neuromuscular
junctions but not at ganglia.

True

Anticholinergic drugs are sometimes useful in the treatment of muscle rigidity in
Parkinsonism.

False

The ‘pseudocholinesterase’ found in blood differs from the ‘true cholinesterase’
found near neuromuscular junctions.

293.

True

The intrinsic ‘myogenic’ response in smooth muscle opposes stretch; skeletal
muscle requires a nerve reflex arc for this type of response.

True

It continues to contract due to local pacemakers.

True

They show spontaneous depolarization between contractions.

False

In smooth muscle, actin and myosin ﬁlaments occur but are less obvious on
microscopy.

True

Smooth muscle has a less well-developed sarcoplasmic reticulum.

294.

False

No such potentials have been recorded here.

True

The hyperpolarization of the anterior horn cell reduces the likelihood of the cell
ﬁring action potentials by moving the membrane potential further from the ﬁring
threshold.

False

Its amplitude is about 5 mV and its duration about 5 msec.

True

It may be produced by increased permeability to potassium or to chloride ions.

True

In this way the post-synaptic cell integrates the various signals it receives.

MCQ

Neuromuscular system – questions

127

Questions 295-300

295. A volley of impulses travelling in a pre-synaptic neurone causes

An identical volley in the post-synaptic neurone.

An increase in the permeability of the pre-synaptic nerve terminals to calcium.

Vesicles in the nerve endings to fuse with the cell membrane and release their contents.

The generation of at least one action potential in the post-synaptic neurone.

Neurotransmitter to travel down the nerve axon.

296. Pain receptors are

Similar in structure to Pacinian corpuscles.

Stimulated by a rise in the local K

⫹

concentration.

Quick to adapt to a constant stimulus.

More easily stimulated in injured tissue.

Stimulated in the wall of the gut by agents which damage the tissues.

297. A property shared by

Skeletal and cardiac muscle is their striated microscopical appearance.

Skeletal and multiunit smooth muscle is that they are paralysed when their motor
nerves are cut.

Cardiac and visceral smooth muscle is their spontaneous activity when denervated.

Skeletal and cardiac ventricular muscle is their stable resting membrane potential.

All varieties of muscle is that contraction strength is related to their initial length.

298. The equilibrium potential (E ) for

An ion species is the membrane potential observed when its concentrations on each side
of the membrane are in equilibrium.

⫹

is about

⫺50 mV in squid axon.

An ion species depends on the ratio of the concentrations of the ion outside (I

) and

inside (I

) the cell.

An ion species is the potential the membrane potential would approach if it became
freely permeable to that ion.

An ion species would be zero if the concentrations of the ion on each side of the mem-
brane were equal.

299. Histological and physiological study of skeletal muscle shows that the

Distance between two Z lines remains constant during contraction.

Width of the anisotropic A band is constant during contraction.

Tension developed is maximal when actin and myosin molecules just fail to overlap.

Stimulus needed to cause contraction is minimal when applied at the Z line.

The T system of transverse tubules opens into the terminal cisterns of the sarcoplasmic
reticulum.

300. Rapid eye movement (REM) sleep differs from non-REM sleep in that

The EEG shows waves of higher frequency.

Muscle tone is higher.

Heart rate and respiration are more regular.

Secretion of growth hormone is increased.

Dreaming is more common.

MCQ

128

Neuromuscular system – answers

Answers

295.

False

The synapse may amplify or attenuate the signal.

True

The uptake of Ca

⫹

by the nerve ending facilitates release of transmitter.

True

The neurotransmitter contained in the vesicles is released by exocytosis.

False

The impulses may be inhibitory; even if they are excitatory, the post-synaptic
neurone may be strongly inhibited by inputs from other pre-ganglionic neurones.

True

Neurotransmitter is thought to be synthesized and packaged in the Golgi appara-
tus in the neurone cell body before travelling down the axon to the nerve termi-
nals.

296.

False

They are bare nerve endings.

True

⫹

salts cause pain when applied to the base of an ulcer.

False

Pain receptors adapt very slowly; this protects the tissues against damage.

True

The sensitivity of pain receptors is increased by local tissue injury (hyperalgesia).

False

Damage to the gut wall by stimuli such as cutting or burning is painless.

297.

True

Both have highly organized actin and myosin ﬁlaments.

True

The iris is an example of multiunit smooth muscle.

True

Isolated hearts and gut segments show spontaneous activity in the organ bath.

True

Only the pace maker cells in the heart have unstable membrane potentials.

True

The Frank–Starling relationship describes this with respect to cardiac muscle.

298.

False

It is the membrane potential that would be required to balance the concentration
gradient for that ion.

False

A positive membrane potential of about

⫹65 mV is required to balance the Na

⫹

concentration gradient.

True

It can be calculated using the Nernst equation:
E

⫽61.5 log

] [I

].valence

⫺1

at 37°C.

True

Membrane potential approaches

⫹65 mV when freely permeable to Na

⫹

True

From the Nernst equation (log

⫽O).

299.

False

This is sarcomere length and it shortens with contraction.

True

Its width is the length of the myosin molecule.

False

It is maximal when action and myosin overlap maximally and when adjoining
actin molecules just fail to overlap.

True

This is where the transverse tubules penetrate the muscle ﬁbre.

False

They are adjacent but are not directly connected.

300.

True

Wave amplitude is reduced also.

False

Surprisingly, muscle tone is low.

False

They are much more irregular.

False

It is inhibited during REM sleep.

True

Subjects woken at the end of REM sleep give vivid accounts of dreams.

MCQ

Neuromuscular system – questions

129

Questions 301–307

301. Hemisection of the spinal cord at C7 on the right side would cause

Greater loss of pain sensation in the right foot than in the left foot.

Greater loss of motor power in the right leg than in the left leg.

Greater loss of conscious proprioception in the right than in the left leg.

Respiratory failure

Loss of the micturition reflex.

302. The ankle jerk reflex is exaggerated

When the arm muscles are voluntarily contracted.

Immediately after complete spinal cord transection at the cervical level.

On the left side some months after damage to the tracts in the right internal capsule.

In extrapyramidal system disorders such as Parkinsonism.

When cerebellar function is lost.

303. Delta (

␦) wave activity in the electroencephalogram

Is low in frequency and amplitude.

Suggests that the patient is alert and concentrating.

When unilateral suggests a brain abnormality.

Is a feature of petit mal epilepsy.

Is more common in children than in adults while they are awake.

304. Increased intracranial pressure may cause

Cranial enlargement in children.

Squinting and loss of smell sensation in children.

Cupping of the optic disc.

An increase in cerebral blood flow.

Arterial hypertension.

305. Pain receptors in the gut and urinary tract may be stimulated by

Cutting through their wall with a sharp scalpel.

Distention.

Inflammation of the wall.

Acid fluid.

Vigorous rhythmic contractions behind an obstruction.

306. Signs of brainstem death include

Unconsciousness.

Loss of pupillary reaction to light.

Loss of tendon jerks in the arms and legs.

Loss of respiratory response to CO

in the absence of hypoxia.

Nystagmus in response to cold water in the external auditory canal.

307. Spasm of digital vessels in the hands in response to cold (Raynaud’s

phenomenon) may be relieved by

Cutting sympathetic nerves to the hand.

Stimulating parasympathetic nerves to the hand.

Alpha (

␣) adrenoceptor blockade.

Beta (

␤) adrenoceptor agonists.

Wearing gloves.

MCQ

130

Neuromuscular system – answers

Answers

301.

False

The left would be more affected; pain ﬁbres cross the midline shortly after enter-
ing the cord.

True

The main motor tract to the right leg would be severed.

True

The ﬁbres serving proprioception cross at the top of the spinal cord.

False

Diaphragmatic and some intercostal activity would remain intact.

False

The reflex centres for micturition are in the sacral cord.

302.

False

It is not exaggerated but contraction of arm muscles reinforces the reflex.

False

Immediately after cord transection, reflexes below the level of the lesion are lost
in the stage of ‘spinal shock’.

True

Muscle tone increases following contralateral internal capsular lesions.

False

Though muscle tone is increased, tendon jerks are not exaggerated.

False

Muscle tone is low following cerebellar damage and the knee jerk ‘pendular’.

303.

False

Delta waves have slow frequency and large amplitude.

False

It is associated with deep sleep.

True

Delta waves may indicate brain damage as well as deep sleep.

False

This produces a characteristic spike and wave pattern in the EEG.

True

Delta wave activity is seen occasionally in the EEGs of normal awake children.

304.

True

Hydrocephaly occurs because the cranial bone sutures have not closed.

True

The cranial deformity in hydrocephalus may damage cranial nerves.

False

It causes papilloedema – bulging in the opposite direction.

False

Vessel compression may reduce cerebral flow severely.

True

This reflex response helps to maintain cerebral blood flow.

305.

False

The intestine may be cut painlessly during operations under local anaesthesia.

True

Stretch is an adequate stimulus for these receptors.

True

Chemicals released in inflammation lower the pain threshold (hyperalgesia).

True

As with a peptic ulcer.

True

This is the cause of the intermittent pain known as colic.

306.

False

Consciousness is a function of the cerebral cortical neurones.

True

The coordinating centres for pupillary reflexes are in the brainstem.

False

The reflex centres for tendon jerks are in the spinal cord.

True

Respiratory reflexes are coordinated in the brainstem.

False

Nystagmus is the normal reflex response of brainstem centres to this stimulus.

307.

True

Sympathetic nerves to digital vessels are tonic vasoconstrictor nerves.

False

The hand does not have a parasympathetic nerve supply.

True

Alpha receptors mediate sympathetic vasoconstriction.

False

Digital vessels have few beta receptors.

False

Raynaud’s phenomenon is triggered by cold and wearing gloves may prevent
cooling to the threshold temperature.

MCQ

Neuromuscular system – questions

131

Questions 308–314

308. Muscle tone is reduced by

Curare-like drugs.

Lower motor neurone lesions.

Upper motor neurone lesions.

Cerebellar lesions.

Gamma efferent impulses to muscle spindles.

309. Effective treatments for severely raised intracranial pressure include

Removal of cerebrospinal fluid by lumbar puncture.

Reduction of extracellular fluid by diuretics.

Creating an anastomosis between a cerebral ventricle and a neck vein.

Creating an anastomosis between intracranial subdural space and the peritoneal cavity.

Placing the patient recumbent with the legs raised.

310. Disease of the extrapyramidal motor system in Parkinsonism causes

Tremor which is more obvious when the patient is performing skilled movements.

Muscle paralysis.

Increased muscle tone throughout the range of passive movement.

Increased involuntary facial movements during speech.

An unusual gait with small fast regular steps.

311. Lower motor neurone disease

Causes loss of voluntary movements but not of reflex movements.

Is a later stage of upper motor neurone disease.

Causes eventual wasting of the muscles concerned.

Does not affect ventilation of the lungs.

Is associated with involuntary twitchings of small fasciculi in the affected muscles.

312. Blockade of

␣ (alpha) adrenoceptors is likely to cause a reduction in

Sweat production.

Bronchus diameter.

Gastrointestinal motility.

Total peripheral resistance.

Heart rate.

313. Bulging of the optic disc into the vitreous humour (papilloedema) is

caused by

Raised intraoccular pressure (glaucoma).

Blockage of absorption of the aqueous humour.

A rise in intracranial pressure.

Inflammation of the optic nerve.

Interference with the venous drainage of the eye.

314. Atropine (which blocks muscarinic receptors) causes

Paralysis of accommodation for near vision in the eye.

Constriction of the pupil.

Constriction of the bronchi.

Diarrhoea.

Difﬁculty with micturition.

MCQ

132

Neuromuscular system – answers

Answers

308.

True

These paralyse muscle by blocking transmission at neuromuscular junctions.

True

Lower motor neurones also paralyse skeletal muscle.

False

Loss of supraspinal influences results in spasticity of the affected muscles.

True

The cerebellum helps to maintain normal muscle tone.

False

These increase spindle sensitivity to stretch and hence muscle tone.

309.

False

This may cause fatal compression of the brainstem if the medulla is forced
(coned) into the foramen magnum.

True

This reduces formation of cerebrospinal fluid.

True

This facilitates drainage of cerebrospinal fluid.

False

CSF is in the subarachnoid space.

False

This would increase intracranial pressure due to gravitational effects and impair
CSF drainage by raising pressure in the venous sinuses.

310.

False

Parkinsonism causes tremor which is more obvious when the patient is at rest.

False

Paralysis is not a feature of the condition.

True

This is ‘cogwheel’ or ‘lead pipe’ rigidity.

False

The face is mask-like; there is poverty of facial movements.

True

The body’s centre of gravity is shifted forward.

311.

False

The muscles are paralysed and not capable of voluntary or reflex movements.

False

It is totally independent of upper motor neurone disease.

True

It leads to ‘disuse atrophy’.

False

Ventilation will be affected if the phrenic and intercostal nerves are involved.

True

‘Fasciculation’ is due to denervation hypersensitivity; muscles become ultra-
sensitive to small amounts of acetylcholine released from the degenerating nerve
terminals.

312.

False

Sweating is mediated by cholinergic nerves.

False

Bronchial smooth muscle has few alpha receptors; beta blockade tends to cause
bronchoconstriction.

False

Stimulation of alpha or beta adrenoceptors inhibits the gut.

True

Alpha receptors mediate vasoconstriction.

False

The heart has few alpha receptors; beta receptor blockade slows the heart.

313.

False

Glaucoma causes depression (‘cupping’) of the optic disc.

False

This is a cause of glaucoma.

True

Papilloedema is an important sign of raised intracranial pressure.

True

Optic neuritis causes swelling of the optic disc.

True

This causes local oedema involving the disc.

314.

True

By paralysing the ciliary muscles.

False

It causes pupillary dilatation by paralysing circular muscle in the iris.

False

It tends to dilate the bronchi by blocking vagal effects.

False

It causes constipation by suppressing bowel activity.

True

Micturition depends on cholinergic nerves.

MCQ

Neuromuscular system – questions

133

Questions 315–320

315. Visceral pain

Is poorly localized compared with pain arising in skin.

Is often felt in the mid line.

May cause reflex contraction of overlying skeletal muscle.

May cause reflex vomiting.

May cause reflex changes in arterial blood pressure.

316. Posterior column damage in the spinal cord may impair

Vibration sense.

Pain sensation.

The flexor plantar response to stimulation of the sole.

Touch sensation.

The ability to stand steadily with the eyes closed.

317. Aphasia

Is an impairment of language skills without motor paralysis, loss of hearing or vision.

Implies impairment of consciousness.

Is called motor aphasia if the patient understands what the speech sounds and symbols
mean but lacks the higher motor skills needed to express them.

Is called sensory aphasia if the patient does not understand the meaning of the words he
hears, sees and uses.

Usually results from right-sided cortical damage.

318. Blockade of parasympathetic activity causes a reduction in

Sweat production.

Resting heart rate.

The strength of skeletal muscle contraction.

Salivation.

Intestinal motility.

319. Sensory disturbance consisting of

Pain, sensory loss and paraesthesiae in one leg suggests a spinal cord lesion.

Loss of pain, temperature but not touch sensation in the arms suggests a spinal cord
lesion.

Loss of two-point discrimination but not touch sensation suggests a lesion in the thala-
mus.

Loss of all sensations on the left side suggests a right internal capsule lesion.

Loss of all sensations in a skin region suggests a peripheral nerve or posterior root
lesion.

320. Damage to the cerebral cortex may cause loss of

Pain sensation on the opposite side of the body.

Reflex thermoregulatory activity.

Skilled movements in the absence of paralysis.

Ability to identify an object by its tactile characteristics.

Vision in one eye only.

MCQ

134

Neuromuscular system – answers

Answers

315.

True

This is characteristic of visceral pain.

True

However pain from some viscera such as ureters and bile ducts is lateralized.

True

In the abdomen this is seen as ‘guarding’.

True

Visceral pain is often associated with autonomic side effects.

True

Another example of autonomic side effects, pressure may increase or decrease.

316.

True

The ﬁbres carrying this sensation travel in the posterior columns.

False

The ﬁbres carrying pain sensation travel in the spinothalamic tracts.

False

The reflex does not depend on posterior column ﬁbres.

True

The ﬁbres responsible for ﬁne touch sensation travel in the posterior columns.

True

Proprioceptive information is important in maintaining balance and it is carried
in the posterior columns.

317.

True

It is a cortical dysfunction.

False

Level of consciousness is an independent entity.

True

It may start with an inability to say the names of familiar objects but end up with
loss of virtually all verbal communication skills.

True

Patients with sensory aphasia tend to talk rubbish since they are unaware of the
errors in their use of language.

False

Language skills are carried in the left hemisphere in right and some left-handed
people.

318.

False

Sweat glands are innervated by sympathetic cholinergic nerves.

False

Resting heart rate rises due to blockade of vagal tone.

False

Parasympathetic nerves are not involved in skeletal muscle activity.

True

Dryness of the mouth results from blockade of salivary secretion.

True

Parasympathetic nerves are motor to intestinal smooth muscle.

319.

False

Pain is uncommon with spinal cord lesions; the symptoms suggest irritation of a
sensory root or peripheral nerve.

True

The ﬁbres carrying these sensations run in separate tracts in the spinal cord.

False

It suggests a parietal cortex lesion where such sensory discriminations are made.

False

It suggests right-sided brain-stem damage since pain is appreciated at subcorti-
cal level.

True

Only peripheral nerves and posterior roots carry all modalities of sensation
together from a circumscribed skin area.

320.

False

The cerebral cortex is not involved in the conscious appreciation of pain.

False

Reflex thermoregulation is organized in the hypothalamus.

True

Such loss of skilled movements is called ‘apraxia’.

True

This ‘asteriognosia’ results from parietal cortex damage.

False

Damage to the visual cortex causes loss of part of the visual ﬁeld in both eyes.

MCQ

Neuromuscular system – questions

135

Questions 321–326

321. In the hemiplegia following a right-sided cerebrovascular accident

(stroke)

Left-sided muscle weakness is evident.

Muscles in the left side of the body are unable to contract.

Muscles which act on both sides of the body, such as respiratory muscles, tend to be
spared.

Skilled movements are better preserved than unskilled movements.

Speech movements are better preserved than swallowing movements.

322. Characteristic features of cerebellar disease include loss of

Muscle tone.

Muscle strength.

Conscious muscle-joint sense.

Ability to make precise muscle movements.

Ability to ﬁx the gaze steadily on an object.

323. Long-term consequences of transection of the spinal cord in the lower

cervical region include

Loss of thermoregulatory sweat production in the legs.

Severe flexor spasms when the skin of the legs is stimulated.

Paralysis of bladder muscle.

Inability to regulate sympathetic tone in leg blood vessels in response to baroreceptor
stimulation.

Inability to erect the penis and ejaculate semen.

324. Blockade of

␤ (beta) adrenoceptors is likely to cause

Decreased intestinal motility.

Worsening of the condition in patients with bronchial asthma.

Worsening of the condition in patients in cardiac failure.

Inability to increase heart rate during exercise in patients with transplanted hearts.

Inability to increase blood flow to exercising muscles.

325. Cutaneous pain

Can be caused by overstimulation of touch receptors.

Can be caused by excitation of receptors by chemicals released in injured tissue.

Can be elicited more readily if the tissue has been injured recently.

Receptors adapt to stimulation more quickly than touch receptors.

Transmission at spinal cord level is facilitated by opening of potassium channels in the
post-synaptic membrane.

326. Headache can be produced by

Dilatation of intracranial blood vessels.

Constriction of extracranial blood vessels.

Meningeal irritation.

Blood in the cerebrospinal fluid.

Loss of cerebrospinal fluid following lumbar puncture.

MCQ

136

Neuromuscular system – answers

Answers

321.

True

Voluntary movements such as making a handgrip are abnormally weak.

False

Voluntary control is lost but the muscles can contract in reflex, synergistic and
other involuntary movements.

True

Perhaps because they have bilateral cortical representation.

False

The most affected movements are those requiring high levels of cortical control.

False

The vocal cord movements required for speech are more highly skilled than those
required for swallowing.

322.

True

Muscle tone depends in part on the integrity of the cerebellum.

False

Muscle strength does not depend on the cerebellum.

False

Cerebellar activity depends on unconscious, not conscious, proprioception.

True

Loss of muscular coordination causes ‘intention tremor’.

True

The jerky eye movement in cerebellar disease when the gaze is ﬁxed on an object
is called ‘nystagmus’.

323.

True

Thermoregulatory control is coordinated through the sympathetic nervous system
by centres in the hypothalamus.

True

Due to exaggeration of the spinal withdrawal reflex.

False

Both micturition and defaecation can occur reflexly (their reflex centres are in
the sacral cord) but are no longer under voluntary control.

True

This impairs the control of arterial blood pressure, especially in the erect position.

False

These are spinal reflexes with centres in the lumbosacral region of the spinal
cord.

324.

False

Alpha and beta adrenoceptor stimulation in gut inhibits smooth muscle.

True

By blocking the bronchodilatory action of adrenaline and noradrenaline.

True

By several mechanisms including blocking the sympathetic drive to the heart.

True

By blocking the chronotropic effect of circulating catecholamines.

False

Increased flow in exercise depends on local metabolites, not beta adrenoceptors.

325.

False

Pain is due to excitation of speciﬁc pain receptors.

True

Such substances include histamine, bradykinin, 5-hydroxytryptamine, prosta-
glandins, nitric oxide and substance P.

True

Chemicals released in the injured tissue reduce the stimulation threshold to cause
hyperalgesia.

False

Pain receptors adapt much more slowly than touch receptors.

False

This would inhibit synaptic transmission and may explain how enkephalin and
endorphin modulate transmission of pain impulses in the substantia gelatinosa.

326.

True

Probably due to pain receptors in vessel walls stimulated by stretch.

False

Dilatation of these extracranial vessels occurs in patients with throbbing
migraine-type headaches that are relieved by certain vasoconstrictor agents.

True

This causes the severe pain and neck stiffness in early meningitis.

True

Surprisingly, blood also irritates the meninges to cause headache and neck stiff-
ness.

True

The brain tends to sag in the cranium and pull on pain receptors in the meninges.

MCQ

Neuromuscular system – questions

137

Questions 327–330

327. Depressed brain function causes

Disorders of function which are independent of the cause of the depression.

Loss of unskilled movements before loss of skilled movements.

Restlessness and delirium before stupor and coma.

A progressive fall in the amplitude of waves in the EEG.

Depression of ventilation before loss of consciousness.

328. Loss of pain sensation in the

Feet may lead to skin ulceration.

Knee may lead to joint damage.

Ears and ﬁngers usually precedes frostbite.

Leg follows surgical division of the spinocerebellar tracts in the spinal cord.

Face follows surgical division of the facial nerve.

329. Intracranial pressure tends to rise when

Cerebral venous pressure rises.

Forced expiration is made against a closed glottis.

There is a bout of coughing.

Cerebral blood flow increases.

Arterial P

falls below normal.

330. Severe pain may lead to

A fall in blood pressure due to a fall in vascular resistance in skeletal muscle.

A fall in heart rate due to an increase in cardiac vagal tone.

Vomiting through a reflex centre in the brainstem.

Profuse sweating due to activation of sympathetic nerves.

Suppression of cortisol secretion.

MCQ

138

Neuromuscular system – answers

Answers

327.

True

Alcohol, lack of oxygen, low blood sugar and hypothermia all impair cellular
function in the brain and lead to a recognizable syndrome of neurological effects.

False

Higher critical functions depending on cortical cells are ﬁrst to go, e.g. driving
ability.

True

Coma implies that cellular depression has reached the less sensitive cells in the
brainstem mediating consciousness.

False

Amplitude increases initially to give delta waves in light coma before falling
later.

False

This brainstem function is preserved until the later stages of deep coma.

328.

True

Probably because of failure to protect the foot and letting minor injury persist
without attention.

True

Again due to loss of the protective effects of pain.

True

Nerve ﬁbres stop conducting near freezing point so there is no further warning
when freezing causes tissue damage.

False

Pain sensation is blocked by surgical division of the spinothalamic tracts.

False

It is lost following division of the sensory root of the trigeminal nerve.

329.

True

This distends intracranial veins and hence raises pressure within the cranium.

True

This (Valsalva) manoeuvre raises cerebral venous pressure.

True

This also raises cerebral venous pressure.

True

The vasodilation raises the volume of blood within the cranium.

False

This constricts cerebral vessels and reduces cerebral blood volume.

330.

True

This lowers total peripheral resistance.

True

Consciousness may be lost if this is combined with muscle vasodilation in the
‘vasovagal’ syndrome.

True

The vomiting centre is in the medulla oblongata.

True

Sympathetic cholinergic nerves are motor to sweat glands.

False

Severe pain increases cortisol secretion via the hypothalamus as part of the
general response to trauma.

MCQ

NEUROMUSCULAR SYSTEM

139

EMQs

Questions 331–340

EMQ Question 331

For each case of coma A–E, select the most appropriate option from the following list.

1. Hyperthermia.

2. Hypothermia.

3. Respiratory failure.

4. Hepatic failure.

5. Renal failure.

6. Diabetic ketoacidosis.

7. Hypoglycaemia.

8. Drug overdose.

9. Hypothyroidism.

10. Raised intracranial pressure.

11. Brainstem death.

12. Persistent vegetative state.

A 70-year-old woman has been found in her kitchen unconscious when neighbours
noted that she had failed to appear as usual for the second day running. On admission
to hospital she is noted to have markedly cold skin but this is attributed to the current
cold spell and not regarded initially as serious since the clinical thermometer shows
only a slightly low body temperature at 35.5

A 5-year-old child admitted after a road trafﬁc accident has been deeply unconscious
since admission several days ago and is maintained on a ventilator. There is no response
of the pupils to light and the corneal response is also absent. Instillation of ice-cold
saline into the external auditory meatus produces no eye movements and there is no
spontaneous breathing when ventilation is suspended (after pre-oxygenation) to allow
the carbon dioxide level in arterial blood to rise to 50 per cent above normal.

A 10-year-old child has been admitted in coma with a history of rapid deterioration
with vomiting over the previous two days. Recently the child had lost weight and had
been passing urine in large amounts more frequently than usual. Hyperventilation is
noted. Laboratory investigations results include a pH of 7.1 and a bicarbonate level of
9 mmol per litre.

A 35-year-old man known to ambulance personnel as a diabetic has been brought
unconscious to hospital. His heart rate is 90 per minute and the pulse is strong, with
blood pressure 150/50. Marked sweating is noted.

A 30-year-old man was admitted to hospital in an ‘intoxicated’ state and with a history
of vomiting a cupful of blood on the day of admission. He subsequently became drowsy
and lapsed into coma, despite transfusion of blood. He is noted to have yellow dis-
colouration of the skin and sclera.

EMQ

140

Neuromuscular system – answers

Answers for 331

Option 2

Hypothermia. ‘Accidental’ hypothermia tends to affect people of all ages

when immersed in cold water or exposed on land to low temperatures without adequate
insulation; it also occurs in elderly people during cold weather, usually when they have
suffered an illness such as a stroke which means they lie poorly insulated in a relatively
low temperature. Diagnosis requires a low reading thermometer, usually inserted rectally,
since a clinical thermometer is shaken down to an initial temperature around 35–36°C and
this may be taken as the temperature even though the True temperature is 5–10 degrees
below this. The markedly cold skin is an important clue. Treatment of such patients is
often unsuccessful since they have the damage produced by hypothermia added to the
underlying condition such as a stroke in this case.

Option 11

Brainstem death. This diagnosis is only made after careful repeated expert

examination and after reversible causes such as Options 2, 8 and 9 have been excluded.
Survival of the brainstem would be indicated by preservation of the brainstem corneal and
pupillary reflexes, by the presence of nystagmus (jerky eye movements) provoked by stim-
ulation of the vestibular system by the icy saline and by spontaneous breathing move-
ments in the presence of a high carbon dioxide level. (The pre-oxygen ﬁlls the functional
residual capacity with oxygen to prevent hypoxic damage during removal from the ven-
tilator.)

Option 6

Diabetic ketoacidosis. This is a typical history of childhood-onset of insulin-

dependent diabetes mellitus. Lack of insulin’s action leads to failure to assimilate absorbed
glucose and other nutrients into the body cells, with resulting malnutrition and glycosu-
ria leading to polyuria. In the absence of adequate intracellular glucose, energy produc-
tion relies excessively on fat as a substrate and this leads to ketones and a huge excess of
hydrogen ions (severe metabolic acidosis with pH 7.1 and bicarbonate down to about a
third of normal due to buffering). This in turn leads to vomiting, coma and hyperventila-
tion to compensate to some degree for the acidosis by lowering the carbon dioxide level.
The blood glucose level would be 5–10 times normal.

Option 7

Hypoglycaemia. This patient contrasts with the previous one in that he is

known to be a diabetic and his condition suggests a low blood sugar. This is suggested by
the hyperdynamic circulation, a compensation for hypoglycaemia (in contrast, ketoacido-
sis is associated with a weak pulse and circulatory failure). The sweating is also a sympa-
thetic autonomic response to hypoglycaemia. The initial treatment is an intravenous
injection of concentrated glucose. Such patients not uncommonly have repeated episodes
of unconsciousness due to hypoglycaemia and become known to ambulance personnel.

Option 4

Hepatic failure. The major clue here is the jaundice (yellow discolouration)

which suggests a hepatic cause of coma. Hepatic failure often causes in the early stages a
state similar to alcoholic intoxication and indeed the two could co-exist as excessive alco-
holic consumption is a common cause of hepatic failure. However, in this case vomiting
of blood has occurred (common in hepatic failure complicated by portal hypertension and
oesophageal varices). It is likely that some of the blood lost will have been digested and
the products of digestion absorbed from the gut. Digestion and absorption of this high
protein load could cause hepatic coma to develop precipitated by toxic products of pro-
tein digestion which cannot be eliminated by the liver.

EMQ

Neuromuscular system – questions

141

EMQ Question 332

For each case of neurological abnormality due to damage in the nervous system A–E, select
the most appropriate option for the site of that damage from the following list of sites for the
damaged area (lesion).

1. Lower motor neurones (peripheral).

2. Upper motor neurones (central).

3. Left cerebral hemisphere.

4. Right cerebral hemisphere.

5. Left half of spinal cord.

6. Right half of spinal cord.

A 40-year-old man has noticed that his right leg feels ‘different’, but he has not noticed
any weakness. On testing, his right leg is not as good as the left at detecting a pin-prick
or a cold metallic object.

An 80-year-old woman is found to have moderate weakness on one side of her body.
She seems fairly aware of her surroundings but appears not to be able to speak.

A 20-year-old man was involved in a motor bike crash a month ago. He has weakness
and clumsiness in his right arm but there is no abnormality of feeling. The thenar emi-
nence on the right is flatter than that on the left. The biceps reflex on the right is
weaker than that on the left.

A 70-year-old woman developed weakness in her right arm and leg a month ago and
was admitted to hospital. The weakness is still present in her right arm and sensation is
not as good as in the left. The biceps reflex on the right is stronger than that on the left.

A 30-year-old man in a wheelchair has severe weakness of both legs. The leg reflexes
are brisker than normal.

EMQ Question 333

For each of the reflex systems A–E, select the most appropriate option for the anatomical loca-
tion of the reflex centres from the following list.

1. Spinal cord.

2. Hypothalamus.

3. Cerebral cortex.

4. Cerebellum.

5. Brainstem.

6. Cervical spinal segments.

7. Thoracic spinal segments.

8. Lumbar spinal segments.

9. Sacral spinal segments.

Reflexes coordinating the activities of some pelvic organs.

Reflexes coordinating vascular tone in the skin, sweating and general skeletal muscle
tone to maintain normal core temperature.

Reflexes coordinating the increases in peripheral vascular resistance that occur on
changing from the lying down to the standing up position.

Reflexes coordinating the acts of swallowing and vomiting.

Reflexes coordinating the biceps and quadriceps jerks.

EMQ Question 334

For each physiological description A–E, select the most appropriate option from the following
list of axons.

1. Small unmyelinated axons.

2. Large myelinated axons.

3. Small myelinated axons.

4. Large unmyelinated axons.

5. Motor axons.

6. Sensory axons.

7. Autonomic axons.

8. Somatic axons.

Axons which are concerned with reflex responses affecting cardiac function.

Axons which transmit motor impulses in the knee jerk reflex.

Axons which transmit sensory impulses in the knee jerk reflex.

Axons which transmit impulses around the lower end of the velocity range, around one
metre per second.

Axons which transmit impulses by saltatory conduction at around the upper end of the
velocity range, around 50 metres per second.

EMQ

142

Neuromuscular system – answers

Answers for 332

Option 5

Left half of spinal cord. This man has impaired pain and temperature sensa-

tion in his right leg. These sensory modalities are conveyed in pathways which cross the
mid line soon after entry to the spinal cord, so the lesion is in the left side, affecting the
spino-thalamic tract.

Option 3

Left cerebral hemisphere. The age and symptoms are typical of a ‘stroke’. We

are not told the side of the weakness, but since the left cerebral hemisphere is concerned
with speech in the great majority of people, the lesion is most likely to be in the left than
the right hemisphere.

Option 1

Lower motor neurones. Weakness without sensory loss suggests a motor

abnormality. Wasting and impaired reflexes are typical of a lower motor neurone lesion.

Option 3

Left cerebral hemisphere. Persisting weakness of an upper motor neurone

type (brisk reflex), together with loss of sensation suggest the effects of a stroke affecting
the brain on the opposite side.

Option 2

Upper motor neurones. This man has bilateral upper motor neurone weak-

ness of the legs with typically increased reflexes. A common cause would be a spinal cord
injury, in which case further testing should show serious sensory loss on both sides.

Answers for 333

Option 9

Sacral spinal segments. This region is like a minor accessory brain in co-

ordinating micturition and defaecation and contributing to sexual reflexes.

Option 2

Hypothalamus. This is the region where responses to both hot and cold envi-

ronments are coordinated. A hot environment favours vasodilation and sweating; a cold
environment favours vasoconstriction and increased skeletal muscle tone.

Option 5

Brainstem. This is the region where the arterial baroreceptor reflexes are

coordinated.

Option 5

Brainstem. This is also the site for the swallowing and vomiting reflexes.

Option 1

Spinal cord. The tendon reflexes in the limbs, such as the biceps and quad-

riceps jerks in response to striking their tendons, are spinal reflexes; they are not conﬁned
to any one region of the cord.

Answers for 334

Option 7

Autonomic axons. Cardiac function is modiﬁed by sympathetic and para-

sympathetic autonomic motor nerves. These responses are informed by autonomic sensory
ﬁbres, e.g. from baroreceptors. Though in general these are small unmyelinated axons,
some of the preganglionic motor ﬁbres are myelinated and a little larger.

Option 2

Large myelinated axons. The somatic tendon jerks involve very rapid

responses, for which large myelinated axons (around 15 microns diameter) are required.

Option 2

Large myelinated axons. It is logical to have impulses carried at similar high

speeds in both sensory and motor halves of the reflex arc.

Option 1

Small unmyelinated axons. Such axons (around 1 micron diameter) carry

impulses where speed of response is low, as with slow pain and many autonomic
responses.

Option 2

Large myelinated axons. The reason for the high speed is that saltatory con-

duction jumps the relatively long internodal distance in these axons at the speed of an
electric current.

EMQ

Neuromuscular system – questions

143

EMQ Question 335

For each paragraph on an aspect of pain A–E, select the most appropriate option from the fol-
lowing list.

1. Chemical mediators at site of pain.

2. Medium sized myelinated pain afferents.

3. Small unmyelinated pain afferents.

4. Gating of the pain pathway in the spinal

5. Thalamus.

cord.

6. Endorphins and enkephalins.

7. Impulse spread to medullary reflex centre.

8. Impulse spread to vagal nuclei.

A pin prick to the foot gives rise to a sudden sharp sensation of pain and withdrawal of
the affected limb.

A relatively crude non-speciﬁc sensation of pain is believed to be generated from the
site of synapse of ﬁbres in the spino-thalamic tracts.

Severe pain is usually treated with drugs which act on brain neuronal receptors for
endogenous neurotransmitters believed to be released during severe exercise, especially
when associated with mortal danger.

Patients who suffer the severe crushing pain of a myocardial infarction (heart attack)
often vomit.

The pain of muscle and joint damage associated with a sports injury is often treated
with drugs which inhibit the formation of prostaglandins.

EMQ Question 336

For each case of disordered movement A–E, select the most appropriate option from the fol-
lowing list of areas of neurological damage.

1. One cerebral hemisphere.

2. Extrapyramidal system.

3. Cerebellum.

4. Patchy areas throughout the central

5. Motor neurones.

nervous system.

6. Sensory neurones.

The patient initially notices some weakness and clumsiness in one hand, with wasting of
the thenar eminence. Twitching is noticed on the affected side. The weakness spreads
over some months to both arms and legs so that walking is only possible with support.

The patient walks with a very unsteady, staggering gait. Speech is rather indistinct.
When the patient ﬁxes the gaze to one side, jerking movements of the eyes can be seen.
When asked to touch the examiner’s ﬁnger, the patient’s ﬁnger moves irregularly and
misses the target.

When the patient is sitting at rest, a tremor of the hand and slow ‘vibration’ of the foot
is noticed. The patient has started to walk leaning forward and with small shuffling
steps. On passive bending of the arm, increased resistance is noted.

The patient reports a variety of temporary disturbances, double vision and visual difﬁ-
culties on both sides at different times, weakness and clumsiness in an arm or leg now
and again. With time there has developed more constant difﬁculty and unsteadiness in
walking.

The patient walks a little unsteadily, dragging one foot. Testing shows loss of power and
impaired sensation in the arm and leg on that side.

EMQ

144

Neuromuscular system – answers

Answers for 335

Option 2

Medium sized myelinated pain afferents. These are the A ﬁbres which con-

duct rapidly to give the initial sharp sensation of pain; they also initiate the rapid spinal
withdrawal reflex in response to pain.

Option 5

Thalamus. This is where the spino-thalamic tracts terminate and synapse.

The general unpleasant sensation of pain is generated here, with cortical areas indicating
the site of the pain.

Option 6

Endorphins and enkephalins. These are the endogenous neurotransmitters

on whose receptors the powerful opiate analgesics act to relieve severe pain. Their release
during exercise may contribute to the mood-elevating effects of exercise. They may also
account for temporary absence of severe pain as a result of injury on the battleﬁeld.

Option 7

Impulse spread to medullary reflex centre. The vomiting centre is in the

medullar oblongata and can be activated by severe pain from a variety of causes (reflex
vomiting).

Option 1

Chemical mediators at site of pain. Prostaglandins are believed to be impor-

tant mediators of persistent pain at a site of injury, particularly involving muscles and
joints. Drugs which inhibit prostaglandin formation (NSAIDs: non-steroidal anti-inflam-
matory drugs) are often effective in this type of pain.

Answers for 336

Option 5

Motor neurones. The symptoms are due to gradual destruction of motor neu-

rones, with no suggestion of any sensory loss. Wasting and twitching suggest involvement
of the lower motor neurones. The history is typical of motor neurone disease.

Option 3

Cerebellum. The cerebellum smooths movements and makes them precise.

The patient shows the opposite in the legs causing unsteadiness, in the muscles of speech
causing slurring and in the eyes, causing nystagmus. ‘Intention’ tremors, i.e. shakiness
during movements, are typical of cerebellar disease.

Option 2

Extrapyramidal system. In contrast to the above, this patient has tremors at

rest. The extrapyramidal system provides appropriate muscle tone and associated move-
ments and these are impaired in the patient whose features are typical of Parkinsonism
(an extrapyramidal disorder).

Option 4

Patchy areas throughout the central nervous system. This patient has had a

variety of temporary disturbances involving various scattered regions: optic nerves,
nerves to the eye muscles, regions controlling arm and leg movements. The condition is
intermittent but tends to lead gradually to permanent difﬁculties. This is typical of multi-
ple sclerosis (MS).

Option 1

One cerebral hemisphere. This patient has motor and sensory loss in one side

of the body due to damage in the cerebral hemisphere on the other side. The features are
typical of a patient with moderate recovery from one or more strokes affecting motor and
sensory pathways in one cerebral hemisphere.

EMQ

Neuromuscular system – questions

145

EMQ Question 337

For each physiological description A–E, select the most appropriate option from the following
list of terms related to the autonomic nervous system.

1. Generalized sympathetic activity.

2. Generalized parasympathetic activity.

3. Cholinergic effect.

␣ alpha adrenergic effect.

␤

beta one effect.

␤

beta two effect.

Following a painful injury, a person’s heart rate abruptly falls from 100 to 50 beats per
minute.

In a period of excitement, a person’s heart rate rises to 120 beats per minute and the
person is aware of the heart pounding in the chest.

After a large meal, a person retires to bed, feeling pleasantly relaxed and warm. Heart
rate is 60 per minute, digestion of the meal is proceeding.

A student with asthma inhales a medication which acts by stimulating receptors on
bronchial smooth muscle and is relieved to ﬁnd that the chest tightness and wheeze
associated with breathing have disappeared.

During strenuous sporting activity a 20-year-old has a heart rate of 200 beats per
minute, is highly alert, has moderately dilated pupils and is sweating profusely.

EMQ Question 338

For each description related to muscle spindles A–E, select the most appropriate option from
the following list of terms (fusal

⫽spindle).

1. Sensory, non-contractile region.

2. Motor region.

3. Increased activity in sensory nerve

4. Contraction of extra-fusal ﬁbres.

supply.

5. Relaxation of spindle.

6. Relaxation of extra-fusal ﬁbres.

Striated region at each end of muscle spindles.

A central region of the spindle speciﬁcally adapted to detecting distortion produced by
stretching of the spindle.

A reflex effect produced by increased sensory output from muscle spindles to the central
nervous system.

A direct effect on the spindle produced by contraction of muscles which antagonize the
action of the muscle containing the spindle.

A reflex effect both by increased motor activity to the spindle and by stretching of the
muscle containing the spindle.

EMQ Question 339

For each kind of muscle described A–E, select the most appropriate option from the following
list.

1. Muscle in the wall of the heart.

2. Muscle that moves the skeleton.

3. Muscle in the wall of the small

4. Muscle in the iris of the eye.

intestine.

This type of muscle is striated and has multiple peripherally-placed nuclei.

This type of muscle is not striated and is not spontaneously active.

This muscle is spontaneously active and is richly endowed with

␤

receptors.

This muscle is not striated and is spontaneously active.

This type of muscle is not spontaneously active and is richly endowed with receptors
that respond to acetylcholine and are blocked by ‘muscle relaxants’.

EMQ

146

Neuromuscular system – answers

Answers for 337

Option 3

Cholinergic effect. Severe pain can lead to a burst of activity in cardiac vagal

nerves; these parasympathetic nerves release acetylcholine at their terminals around the
sinuatrial node to cause marked cardiac slowing.

Option 5

␤

effect. Tachycardia and increased force of cardiac contraction are speciﬁc

cardiac sympathetic effects mediated through stimulation of

␤

adrenoceptors in the sin-

uatrial node and the myocardium respectively.

Option 2

Generalized parasympathetic activity. Relaxation is associated with para-

sympathetic activity and antagonized by sympathetic activity; warmth is associated with
relatively high skin blood flow as sympathetic nerves are ‘switched off’; a heart rate of 60,
and digestive activity both require considerable parasympathetic activity to the heart
(vagus nerves) and the gut.

Option 6

␤

effects. Stimulation of

␤

receptors mediates relaxation of bronchial

muscle; such medication is a common inhalational treatment for asthma.

Option 1

Generalized sympathetic activity. A heart rate of 200 is the maximal pre-

dicted for a 20-year-old, it is produced by removal of vagal tone and a maximal level of
sympathetic tone to the heart; increased alertness, dilated pupils and sweating are all indi-
cations of sympathetic activity.

Answers for 338

Option 2

Motor region. A spindle is a modiﬁed muscle ﬁbre and the striated region at

each end is due to actin and myosin arrangements which retain the ability to contact.

Option 1

Sensory, non-contractile region. This is the nuclear bag region which detects

stretching of the spindle and sends information along fast-conducting ﬁbres to the cen-
tral nervous system.

Option 4

Contraction of extra-fusal ﬁbres. This is the reflex response whereby stretch-

ing of the spindle leads to contraction of the muscle containing the spindle.

Option 3

Increased activity in sensory nerve supply. The antagonistic muscles stretch

the muscle and its spindles and the direct effect on the spindle is stimulation of its sen-
sory region and initiation of activity in the nerve endings supplying it.

Option 4

Contraction of extra-fusal ﬁbres. Motor activity to the striated spindle ends

makes them contract and stretch the central sensory region; stretching the muscle also
stretches the spindles within it; in both cases the increased sensory output leads to reflex
contraction of the extra-fusal ﬁbres of the muscle containing the spindles.

Answers to 339

Option 2

Muscle that moves the skeleton. Skeletal muscle has an orderly arrangement

of actin and myosin molecules that gives it a striated appearance under the microscope.

Option 4

Muscle in the iris of the eye. This type of muscle contains actin and myosin

in a more random arrangement and so appears smooth rather than striated; it requires
stimulation of autonomic nerves to make it contract; sympathetic stimulation contracts
radial ﬁbres to dilate the pupil, parasympathetic stimulation contracts circular ﬁbres and
dilates the pupil.

Option 1

Muscle in the wall of the heart. The heart beats spontaneously due to

impulses from the sinuatrial node; sympathetic stimulation of beta one receptors increases
the force of contraction.

Option 3

Muscle in the wall of the small intestine. This type of smooth muscle shows

rhythmical contractions, even when removed from the body.

Option 2

Muscle that moves the skeleton. Skeletal muscle contracts only when stimu-

lated by somatic motor nerves releasing acetylcholine; during general anaesthesia, muscle
relaxation is often provided (e.g. during abdominal operations) by drugs which interfere
with the action of motor nerves on the muscle ﬁbres.

EMQ

Neuromuscular system – questions

147

EMQ Question 340

For each statement A–E about a patient with a long established complete transection of the
spinal cord at the lower cervical region, select the most appropriate option from the following
list of physiological lesions/disturbances.

1. Somatic upper motor neurone lesion.

2. Somatic lower motor neurone lesion.

3. Loss of reflex centre.

4. Loss of sensory input.

5. Loss of sympathetic motor function.

6. Loss of parasympathetic motor function.

The patient has difﬁculty maintaining arterial blood pressure in the upright position
because the total peripheral resistance cannot be appropriately increased.

The patient is unaware of damaging pressure on the lower limbs.

The patient has difﬁculty maintaining normal core temperature in a cool environment
tolerated by other patients.

The patient’s leg muscles are paralysed but can contract in response to striking the
patellar tendon with a patellar hammer.

The patient has lost the normal sweating response in the legs to a hot environment.

EMQ

148

Neuromuscular system – answers

Answers for 340

Option 5

Loss of sympathetic motor function. Normally when upright we maintain

arterial blood pressure by sympathetically induced vasoconstriction, particularly in the
legs; otherwise blood tends to pool there giving postural hypotension.

Option 4

Loss of sensory input. There is no awareness of any sensation in the legs, so

this warning of impending damage is lost.

Option 5

Loss of sympathetic motor function. Sympathetically induced vasoconstric-

tion is also important in retaining core heat in a cool environment.

Option 1

Somatic upper motor neurone lesion. The motor tracts in the spinal cord are

upper motor neurones with respect to the anterior horn cells which give rise to the axons
of the lower motor neurones supplying the leg muscles; the knee jerk is a spinal reflex
independent of upper motor neurones in long-established paraplegia.

Option 5

Loss of sympathetic motor function. Sweating is yet another activity which

relies on an intact sympathetic motor pathway from the reflex centre to the sweat glands
in the skin.

EMQ

SPECIAL SENSES

149

MCQs

Questions 341–347

341. The fovea centralis

Lies where the visual axis impinges on the retina.

Is not crossed by any major blood vessels.

Is the thickest part of the retina.

Has higher visual acuity than other parts of the retina.

Lies on the temporal side of the optic disc.

342. Endolymph

Is found within the membranous labyrinth.

Has a potassium concentration close to that of extracellular fluid.

Bathes the hair cells of the inner ear.

Is electrically negative with respect to perilymph.

Inertia is a factor in the stimulation of receptors in the semicircular canals during rota-
tory acceleration.

343. Olfactory cells

Are epithelial cells which synapse with olfactory nerves.

Generate impulses when stimulated which are relayed in the thalamus.

Are chemoreceptors.

Show little adaptation.

Are more important than taste in appreciating the flavour of food.

344. Adaptation for vision in poor light is

Complete after 2–3 minutes.

Due mainly to dilatation of the pupil.

Due to regeneration of rod but not cone pigments.

Faster if red goggles are worn before entering the dark environment.

More effective for peripheral than central vision.

345. The basilar membrane of the cochlea vibrates

At the same frequency as the applied sound.

With an amplitude which is proportional to the frequency of the applied sound.

With an amplitude which is proportional to the loudness of the applied sound.

Along more of its length when the applied sound has a high rather than a low frequency.

Mainly at the base of the cochlea for the sound frequencies commonly used in speech.

346. The cones in the retina differ from rods in that they are more

Numerous.

Concerned with colour vision.

Sensitive to light.

Concerned with high visual acuity.

Affected by vitamin A deﬁciency.

347. Increasing the salt concentration applied to a ‘salt’ taste bud increases

Its sensitivity to salt.

The amplitude of its generator potentials.

The amplitude of the action potentials generated.

Impulse trafﬁc to the thalamus.

Impulse trafﬁc up the ascending reticular formation.

MCQ

150

Special senses – answers

Answers

341.

True

It detects objects in the centre of the ﬁeld of vision.

True

There are no superﬁcial structures to affect impinging light rays.

False

It is relatively thin due to absence of superﬁcial layers.

True

The above factors contribute to this.

True

It is marked by yellow pigment.

342.

True

Perilymph surrounds the membranous labyrinth.

False

It is similar to that of intracellular fluid.

True

It bathes cochlear and vestibular hair cells.

False

It is positive, of the order of

⫹80 mV.

True

The inertia causes endolymph movements to lag those of the membranous laby-
rinth and displace the hairs of the hair cells.

343.

False

They are modiﬁed nerve cells in the nasal epithelium.

False

Unlike other sensory inputs, olfactory impulses are not relayed in the thalamus.

True

They recognize certain molecular structures.

False

It is the newcomer who recognizes the smell in the room.

True

In their absence, food loses much of its flavour.

344.

False

It takes about 20 minutes.

False

Dilatation of the pupil contributes but regeneration of bleached receptor pigments
is the main factor.

False

Regeneration of cone pigments plays a part.

True

Red light does not bleach rhodopsin.

True

Peripheral vision adapts better to dark conditions; rods predominate peripherally.

345.

True

Harmonics are also faithfully reproduced.

False

Frequency and amplitude need not be related.

True

Hence very loud sounds can damage the basilar membrane.

False

Low frequency vibrations travel further up the cochlea.

True

Speech frequencies (about 1000–3000 Hz) cause maximum vibration in this
region.

346.

False

There are about 6 million cones compared with 120 million rods.

True

Rods alone give achromatic vision.

False

The rods are much more sensitive; their pigment is bleached in bright light.

True

Acuity is highest with foveal (cone) vision.

False

Vitamin A is essential for rhodopsin synthesis for rod vision only.

347.

False

It decreases; taste receptors adapt to stimuli applied to them.

True

Stronger stimuli lead to generator potentials of greater amplitude.

False

There is an increase in impulse frequency, not amplitude.

True

All but olfactory impulses are relayed in the thalamus.

True

All sensory inputs send impulses via collaterals to this system.

MCQ

Special senses – questions

151

Questions 348–353

348. On entering a darkened room, the

Threshold light intensity for the eye starts to rise.

First phase of retinal adaptation is mainly in the cones.

Final phase of retinal adaptation is mainly in the rods.

Adaptation is slower if a long period was spent in bright light beforehand.

Time course for pupillary dilatation is similar to that for dark adaptation.

349. Dilation of the pupil increases the

Amount of light entering the eye.

Refractive power of the eye.

Spherical aberration.

Depth of focus.

Field of vision.

350. The olfactory system can detect

20–40 distinct odours.

Differences in odour between isomers of the same substance.

The direction from which an odour comes.

Small differences in the concentration of the substance responsible for the odour.

Odours better in old than in young people.

351. During accommodation for near vision

More light enters the eye.

The curvature of the cornea increases.

Chromatic and spherical aberration is decreased.

The depth of focus increases.

The visual axes of the two eyes converge.

352. Visual acuity is

A measure of the sensitivity of the retina to light.

Greater in a person with 6/12 (0.5) vision than in one with 6/9 (0.75).

Greater using central than using peripheral vision.

Greater using one eye than using both eyes.

Greater in normal than in colour-blind people.

353. The tympanic membrane

Modiﬁes the frequencies of sound waves impinging on the ear.

Stops vibrating almost immediately after the sound stops.

Bulges outwards when the pharyngotympanic tube is blocked.

Transmits sound more effectively when the small muscles of the middle ear are
contracted.

Cannot transmit sound waves if it is perforated.

MCQ

152

Special senses – answers

Answers

348.

False

It begins to fall in the process of dark adaptation.

True

The initial adaptation is due more to cone adaptation.

True

Rods are slower to adapt but show more profound adaptation.

True

A previous long exposure would bleach most of the rhodopsin so more time
would be needed for its resynthesis.

False

The pupil dilates almost immediately in the dark.

349.

True

This allows rapid adaptation for vision in poor light.

False

The iris has nothing to do with the refractive power of the eye.

True

By permitting light to pass through peripheral, and less perfect, parts of the lens.

False

As with a camera, a wide aperture tends to shorten the depth of focus.

False

Narrowing the aperture in a camera does not result in a smaller picture.

350.

False

It is thought that humans can differentiate between 2000 and 4000 different
odours.

True

The receptors can detect small differences in molecular conﬁguration.

True

Probably due to the different time of arrival of the odour at the two nostrils.

False

Though very low concentrations of odorous substances can be detected, differ-
ences in concentration of more than 30 per cent are needed to detect a difference
in intensity.

False

Olfaction ability falls with age.

351.

False

Less light enters the eye as the pupils constrict.

False

The cornea is not involved in accommodation; the increase in refractive power in
the eye is due to the increased convexity of the lens caused by contraction of the
ciliary muscle.

True

The papillary constriction restricts light rays entering the eye to the centre of the
lens where there is less chromatic and spherical aberration.

True

Due mainly to the improvement in optical characteristic mentioned in (C) above.

True

To allow the object to be focused on the two foveae.

352.

False

It is a measure of the ability to distinguish between (resolve) two points.

False

Acuity is expressed as the ratio of someone’s reading distance compared with
average normal.

True

Visual acuity is maximal at the fovea where cone receptors are predominant.

False

The two images reinforce each other.

False

Visual acuity does not depend on distinguishing colours.

353.

False

It faithfully reproduces the frequencies.

True

It is very nearly ‘critically damped’.

False

It bulges inwards as middle ear air is absorbed.

False

Reflex contraction of these muscles protects by damping vibration transmission.

False

Small perforations cause about 5 decibels loss; complete destruction about 50.

MCQ

Special senses – questions

153

Questions 354–359

354. In the refracting system of the eye

The cornea causes more refraction than the lens.

More refraction occurs at the inner surface of the cornea than at the outer surface.

The lens, by becoming more convex, can more than double the total refractive power of
the eye.

The back surface of the lens contributes more to accommodation than the front.

Ageing reduces the maximum refractive power of the eye.

355. The hair cells in the semicircular canals are stimulated by

Movement of perilymph.

Linear acceleration.

Rotation at constant velocity.

Gravity.

Movement of endolymph relative to hair cells.

356. When light is shone into one eye, the pupil

Constricts even though its optic nerve has been cut.

Responds due to sympathetic nerve activity.

Does not respond if autonomic cholinergic nerves are blocked by local application of
atropine.

In that eye constricts and the opposite pupil dilates.

Does not respond if there is brainstem death.

357. Light from an object to the right of the visual axis

Impinges on the retina in the right eye to the right of the fovea.

Impinges on the retina in the left eye to the left of the fovea.

Generates impulses which travel in the right optic tract.

Generates impulses which produce conscious sensation in the frontal lobe eye ﬁelds.

Forms an inverted image on the retina.

358. The tympanic membranes

Bulge inwards during descent in an unpressurized airplane.

Have an area about twice that of the oval window.

Prevent sound waves from reaching the oval and round windows at the same time.

Transmit only 10 per cent of applied sound energy to the cochlea for sound waves of
1000 Hz.

Transmit sounds in the 500–5000 Hz frequency range with the least loss of energy.

359. Utricles

Are gravity receptors.

Contain calciﬁed granules.

Contain hair cells.

Contain endolymph which communicates with that in semicircular canals and cochlea.

Can initiate reflex changes in muscle tone.

MCQ

154

Special senses – answers

Answers

354.

True

This is because of the large change in refractive index from air to cornea.

False

The outer interface is with air; cornea and aqueous have similar refractive indi-
ces.

False

It can only increase total refractive power by about 15–20 per cent.

False

During accommodation, the front of the lens bulges more than the back.

True

As the lens stiffens, ability to increase convexity when ciliary muscles contract
is diminished.

355.

False

Perilymph is the fluid outside the membranous labyrinth.

False

Their adequate stimulus is angular not linear acceleration or deceleration.

False

A blindfold person is unaware of any sensation when rotated at constant velo-
city, e.g. as on the earth!

False

Gravity produces linear acceleration.

True

During angular acceleration or deceleration, the inertia of the endolymph causes
it to move relative to the hair cells on the walls of the semicircular canals. The
resulting movement of the hair cells generates afferent impulses that travel in the
vestibular nerves.

356.

False

The optic nerve is an essential part of the reflex pathway for the light reflex.

False

It still constricts after the sympathetic nerves are cut.

True

Atropine blocks this parasympathetic action.

False

Both pupils constrict consensually.

True

Failure of the pupils to respond to light is a sign of brainstem death.

357.

False

It impinges to the left of the fovea.

True

The retina of both eyes is stimulated in corresponding or homonymous areas.

False

They travel in the left optic tract to the left occipital cortex.

False

They enter consciousness in the left occipital cortex; frontal eye ﬁelds are con-
cerned with eye movements.

True

As in a camera.

358.

True

Cabin pressure rises above middle ear pressure.

False

Their area is about 20 times as great.

True

This ‘round window protection’ prevents damping of vibrations in the inner ear.

False

At this frequency, over half of the sound energy is transmitted.

True

Impedance matching and auditory acuity are greatest at these frequencies which
are those used in normal speech.

359.

True

They respond to linear acceleration.

True

The inertia of these otoliths enables utricles to respond to linear acceleration.

True

These are stimulated by forces acting on the otoliths.

True

They are all parts of the membranous labyrinth, ﬁlled with endolymph.

True

Muscle tone is reflexly redistributed so that the body can withstand gravitational
stresses.

MCQ

Special senses – questions

155

Questions 360–365

360. The rods in the retina

Contain visual pigment which is more sensitive to red than to blue light.

Are rendered insensitive by ordinary daylight.

Are more widely distributed over the retina than are cones.

Reflect red light more than blue light.

Comprise about 20 per cent of foveal receptor cells.

361. Cones

Are found in the most superﬁcial layer of the retina.

Show a graded depolarization in response to light.

Contain pigments which are more light-sensitive than the rod pigment.

Contain pigments which are most affected by yellow-green light.

Are absent in an individual with colour blindness.

362. The receptor cells serving taste

Are conﬁned to the tongue.

Are stimulated when chemicals diffuse through the overlying epithelium to reach them.

Are primary sensory neurones.

Are histologically different for the four primary taste modalities.

For sweetness are more common at the tip than at the back of the tongue.

363. Sound waves

Are quantiﬁed on the decibel scale which is logarithmic.

With an intensity of 0 decibels are inaudible.

May have an intensity of minus 10 decibels.

With an intensity of 90 decibels are usually painful.

Are heard as a note one octave higher when their frequency increases eight-fold.

364. The frequency of impulses generated by receptors in a utricle is

Related to the orientation of the head.

Higher during travel at 100 than at 20 miles per hour.

Reduced in the weightless conditions in outer space.

Inversely related to the frequency being generated by the opposite utricle.

Related to the impulse frequency being generated by semicircular canal receptors.

365. Aqueous humour

Is produced by diffusion and active transport in the ciliary bodies.

Pressure is close to mean arterial pressure.

Formation depends on the enzyme carbonic anhydrase.

Is absorbed into veins at the junction of the iris and the cornea.

Is more easily absorbed when the pupil is widely dilated.

MCQ

156

Special senses – answers

Answers

360.

False

Rhodopsin absorbs blue-green light with a wavelength around 500 nm.

True

Nearly all rhodopsin in broken down (bleached) in daylight.

True

The ﬁeld of vision using rods is greater than that using cones.

True

Rhodopsin is a red pigment.

False

There are no rods in the fovea.

361.

False

They are in the layer furthest from the vitreous humour.

False

They hyperpolarize in response to light due to closure of Na

⫹

channels in the

membrane.

False

Rhodopsin is the most sensitive of the pigments.

True

Cone pigments absorb light at wavelengths of 440, 535 and 565 nm; yellow-
green light shows up relatively well in dim light.

False

Colour-blind individuals have cones but they lack one or more of the three cone
systems that respond to the three primary colours.

362.

False

They are found also in the soft palate, pharynx and larynx.

False

The microvilli on top of receptors protrude through taste pores into the buccal
cavity.

False

They are receptor cells which synapse with primary sensory neurones.

False

They look alike.

True

Sweet sensation is experienced at the front of the tongue; bitterness at the back.

363.

True

Loudness is related to the logarithm of sound intensity.

False

Zero decibels is the average threshold for hearing.

True

These sounds may be heard by people whose hearing ability is above average.

False

The threshold for pain is around 120 decibels.

False

They sound one octave higher when their frequency is doubled.

364.

True

This determines the plane of the gravitational pull on the otoliths.

False

The utricle is affected by acceleration, not velocity.

True

This can give rise to a form of travel sickness.

False

Often both respond in parallel.

False

The utricles and semicircular canals function independently; utricles respond to
linear acceleration, semicircular canals to angular acceleration.

365.

True

Its crystalloid composition is not identical to that of plasma.

False

It is much lower. Above 20 mmHg is abnormal and suggests glaucoma.

True

Inhibitors of this enzyme reduce formation and are used in treatment of glau-
coma.

True

This area with its overlying trabeculae is referred to as the canal of Schlemm.

False

The iris then blocks access to the canal of Schlemm.

MCQ

Special senses – questions

157

Questions 366–371

366. Rhodopsin, the pigment of the rods is

A purple pigment.

Highly absorbent of red light.

Most sensitive to violet light.

Regenerated in the dark.

Least sensitive to red light.

367. In the visual field of the left eye, an object

In the upper temporal quadrant is detected in the lower nasal quadrant of the retina.

At the centre of the ﬁeld of vision is detected in the optic disc.

Focused on the blind spot is in the nasal half of the visual ﬁeld.

In the temporal half generates impulses which travel the left optic tract.

In the nasal half is more likely to be perceived in binocular vision than one in the tem-
poral half.

368. The basilar membrane

Is broader at the base of the cochlea than at the apex.

Vibrations stimulate receptors to generate impulses at the frequencies of the applied
sounds.

At the base of the cochlea vibrates only to incoming high frequency sounds.

In the apical region vibrates only to incoming sounds of low frequency.

Can be made to vibrate by pressure waves travelling through skull bone.

369. Taste receptors

For sour taste predominate at the sides of the tongue.

May respond to more than one modality of stimulus.

Give rise to a sour taste when stimulated by hydrogen ions.

Cannot detect small (

⬍10 per cent) differences in the concentration of taste-evoking

chemicals.

Respond more to substances in warm solutions than in cold ones even though the sub-
stance concentration is the same in both.

370. An audiogram

Is a plot of hearing loss (or hearing ability) against sound frequency.

Showing equal impairment of air and bone conduction suggests conductive deafness.

Showing hearing loss at low frequencies for air conduction suggests ear drum damage.

Showing loss at 8000 Hz for air and bone conduction suggests basal cochlear damage.

Showing hearing loss at the lower frequencies is common in elderly people.

371. Poor balance is more likely when there is

Semicircular canal rather than cochlear damage.

Impairment of basilar rather than carotid artery blood flow.

Spinothalamic tract rather than posterior column damage.

Dim rather than bright light.

Recent rather than long-standing destruction of one labyrinth.

MCQ

158

Special senses – answers

Answers

366.

False

It is red.

False

It is red because it reflects red light selectively.

False

It is most sensitive to blue-green light (around 500 nm).

True

In the dark retinene and scotopsin combine to form rhodopsin.

True

This is because it reflects the red light.

367.

True

The image is inverted and reversed with respect to the object.

False

The point focused upon is detected at the macula (fovea).

False

The optic disc is medial to the fovea, so the blind spot is in the temporal part of
the ﬁeld of vision.

False

Impulses related to the temporal region of the left ﬁeld of vision cross to the right
at the optic chiasma.

True

The visual ﬁelds of the two eyes overlap, apart from the outer temporal areas.

368.

False

The reverse is true.

False

Nerves cannot transmit impulses at the top frequencies detectable by ear, about
20 000 Hz.

False

At the base, the basilar membrane vibrates to high and low frequency sound
waves.

True

High frequency sounds are damped out before they reach the apex.

True

This supplements the normal ossicular conduction, especially for loud sounds.

369.

True

Receptors for bitter taste predominate on the posterior dorsum of the tongue.

True

Recording from single taste receptors demonstrates that a single receptor can
respond to more than one modality.

True

All acids taste sour.

True

Taste receptors are poor at discriminating between intensities; a concentration
difference of more than 30 per cent is needed for discrimination.

True

Food flavour is accentuated when hot; unpleasant medicine less offensive when
cold.

370.

True

It is obtained using an audiometer.

False

In conductive deafness air conduction, but not bone conduction, is impaired.

True

This is an example of conductive deafness.

True

This can be caused by acoustic trauma, e.g. in heavy industry.

False

Hearing loss in the elderly (presbycusis) particularly affects higher frequencies.

371.

True

The cochlea does not contribute sensory information needed for balance.

True

The basilar artery supplies brain stem areas particularly concerned with balance.

False

The posterior columns transmit proprioceptive information needed for balance.

True

Vision can compensate for loss of proprioception.

True

Abrupt loss of input causes severe disturbance followed by gradual adaptation.

MCQ

Special senses – questions

159

Questions 372–377

372. In someone with short-sightedness (myopia)

The eye tends to be longer than average from lens to retina.

A convex lens is required to correct the refractive error.

Close vision is affected more than distance vision.

The near-point is farther than normal from the eye.

A circular object tends to appear oval.

373. Colour blindness

Results from inability to detect one of the three primary light colours, red yellow and
blue.

Where red and green are indistinguishable is due to failure of red and green cone
systems.

In which no colours can be detected is due to failure of all the cones systems.

Is more common in women than men.

Is a disability linked to the Y-chromosome.

374. Local application of atropine to the eye causes

Dilation of the pupil.

The near-point for clear vision to move closer to the eye.

Inability to focus on objects at inﬁnity.

Reduced drainage of aqueous humour.

Difﬁculty in looking upwards.

375. In the middle ear

Destruction of the auditory ossicles abolishes hearing.

Paralysis of the auditory muscles makes sounds more faint.

Immobilization of the stapes causes greater deafness than removal of the ossicles.

Air pressure is normally atmospheric pressure.

The round window moves reciprocally with the oval window.

376. Interruption of the visual pathway in the

Left optic tract causes blindness in the right visual ﬁeld (right homonymous hemiano-
pia).

Optic chiasma causes blindness in the nasal half of each visual ﬁeld (binasal hemiano-
pia).

Left optic radiation causes loss of vision to the right.

Occipital cortex causes loss of the light reflex.

Occipital cortex causes loss of central vision with preservation of peripheral vision.

377. Squinting (strabismus) may result from

Poor vision in one eye in childhood.

A refractive error in childhood.

Central suppression of vision in one eye in childhood.

Damage to the cerebellum.

Damage to the internal capsule.

MCQ

160

Special senses – answers

Answers

372.

True

Hence distant objects are focused in front of the retina.

False

A concave lens is required.

False

It is distant objects that appear out of focus.

False

Myopic people can focus on objects closer to the eye than normal people.

False

This is caused by an asymmetrical cornea (astigmatism).

373.

True

One or more of the three types of cone fails to function.

False

It is due to failure of one of the two systems.

False

It is due to the presence of only one functioning cone system.

False

It is 20 times more common in men.

False

Its linkage to the X-chromosome explains its greater frequency in men.

374.

True

This paralyses the cholinergic constrictor ﬁbres.

False

The ciliary muscle needed for accommodation has cholinergic innervation.

False

When focusing at inﬁnity, the ciliary muscle is at rest.

True

The iris tends to obstruct the canal of Schlemm in the corneoscleral angle.

False

Extraocular muscles are not affected by atropine.

375.

False

Sound can still be transmitted by bone conduction.

False

These muscles damp vibration of the ossicles reflexly in response to loud noises.

True

Immobilization prevents the oval window vibrating and causes severe deafness.

True

Air pressure is atmospheric, due to the patency of the pharyngotympanic tubes
connecting the pharynx to the middle ear.

True

Fluid (endolymph) cannot be compressed; as the oval window moves in, the
round window moves out.

376.

True

The left half of each retina is concerned with vision to the right and impulses
from them travel in the left optic tract.

False

The crossing ﬁbres come from the nasal half of each retina and are responsible
for temporal vision; bitemporal hemianopia results.

True

As with damage to the left optic tract.

False

This is a brain stem reflex.

False

The reverse is true because the fovea is bilaterally represented in the cortex.

377.

True

Poor vision in one eye impairs ﬁxation of the eye concerned.

True

A refractive error impairs vision in the eye concerned to give poor ﬁxation.

False

Suppression of vision in one eye is a consequence, not a cause, of squint.

False

Cerebellar damage may cause involuntary oscillatory movements (nystagmus)
but not squinting.

True

Internal capsular damage may cause a paralytic squint due to damage to the ocu-
lomotor tracts.

MCQ

Special senses – questions

161

Questions 378–384

378. Impairment of the sense of smell

May be conﬁned to certain odours only.

May occur in hydrocephalus.

Is likely after thalamic damage.

Can be caused by inflammation of the nasal mucosa.

Is a recognized effect of temporal lobe tumour.

379. Involuntary oscillatory eye movements (nystagmus)

Do not occur in healthy people.

May result from cochlear disease.

Occur in cerebellar disease.

Occur when cold fluid is run into one external ear canal.

Do not affect acuity of vision.

380. Typical effects of ageing on the special senses include gradual loss of

Near vision.

Olfactory sensitivity (hyposmia).

90 per cent of the accommodative power of the lens during the lifespan.

Hearing affecting bone and air conduction similarly.

Hearing affecting high and low frequencies similarly.

381. A child who focuses an object on the fovea of the left eye and on the tem-

poral side of the fovea in the right eye is likely to have

A divergent squint.

A refractive error.

Suppression of vision in the left rather than in the right eye.

No suppression of vision in one eye if the left eye is covered for part of each day.

A lesser tendency to suppression of vision in one eye if given exercises requiring binoc-
ular vision.

382. In unilateral vestibular disease, typical features include

The sensation that the external world is revolving.

Prolonged nystagmus when cold water is placed in the external auditory meatus on the
affected side.

A tendency to stagger when walking.

A tendency to fall in the dark.

Nausea and vomiting.

383. Impairment of visual acuity in bright light can be explained by

Random light scattering when there is deﬁcient pigmentation of the eye due to albinism.

Random light scattering when there is asymmetrical corneal curvature due to astigmatism.

Random light scattering in the cornea when there is vitamin A deﬁciency.

Impairment of rod function when there is vitamin A deﬁciency.

Inability to alter the focal length of the lens when a cataract is present.

384. In long-sightedness (hypermetropia)

Objects at inﬁnity cannot be focused sharply on the retina.

Objects at the usual near-point are focused behind the retina.

Ciliary muscle contracts more strongly to bring objects in mid-visual range into clear
focus.

The range of unblurred vision (near-point to far-point) is greater than normal.

The near-point can be brought closer to the eye by the use of a biconcave lens.

MCQ

162

Special senses – answers

Answers

378.

True

If only some of the many receptor types involved in olfaction are lost.

True

Due to damage to the olfactory nerves by distortion of the cranium.

False

Smell pathways do not pass through the thalamus.

True

This can prevent odours reaching the receptor cells.

False

It may indicate a frontal lobe tumour.

379.

False

They occur when a normal person stops rotating.

False

Disease of the semicircular canals may cause nystagmus.

True

Nystagmus is an ataxia of eye ﬁxation.

True

Due to cooling of fluid in the adjacent semicircular canal.

False

The rapid eye movements tend to make vision blurred.

380.

True

Recession of the near point is typical of the ageing eye (presbyopia); vision at
20–30 cm deteriorates.

True

It affects over 70 per cent of elderly people.

True

It falls from 10–15 dioptres in childhood to 5–10 at 30 and to about 1 dioptre at 70.

True

It is a sensorineural deafness (presbycusis).

False

High-pitched sounds are more affected.

381.

False

The right eye is converging making it a convergent squint.

True

Refractive errors are a common cause of squinting.

False

Suppression of vision tends to occur in the non-ﬁxing eye.

True

Covering the ‘good’ eye helps to preserve vision in the non-ﬁxing eye.

382.

True

Unbalanced vestibular input causes this sensation (vertigo).

False

In this ‘caloric’ test, reduction in nystagmus duration indicates vestibular abnor-
mality.

True

Due to inappropriate information affecting brain areas controlling balance.

True

Compensating visual stimuli are then eliminated.

True

Unbalanced, excessive or reduced vestibular inputs cause nausea and vomiting as
seen in sea-sickness and space-travel sickness.

383.

True

Normally absorption of light by dark pigment in the choroid prevents back-
scattering of light into the retina.

False

There is a refractive error but not random light scattering.

True

Lack of vitamin A leads to keratin deposition in corneal epithelium (xerophthal-
mia).

False

Rod function does not determine acuity in bright light.

False

Impairment of acuity with cataract is due to random scattering by lens opacities.

384.

False

This is true of shortsightedness (myopia).

True

The eye is usually shorter than normal.

True

This distance is closer than usual to the hypermetrope’s near point.

False

It is less than normal; the far point stays at inﬁnity but the near point is further
away.

False

A convex lens is required to augment the power of the eye’s refracting system.

MCQ

SPECIAL SENSES

163

EMQs

Questions 385–394

EMQ Question 385

For each term related to vision A–E, select the most appropriate option from the list below.

1. Normal vision.

2. Determined by the maximum convexity the

lens can attain.

3. Usually involves contraction of the

4. Causes reflex contraction of circular

ciliary muscles.

smooth muscle in the iris.

5. Due to loss of lens elasticity with ageing.

Presbyopia.

Pupillary light reflex.

The near point.

Accommodation.

Emmetropia.

EMQ Question 386

For each visual term A–E, select the most appropriate option from the following list of descrip-
tions.

1. Contain the least light-sensitive

2. The minimum amount of light that elicits

pigments in the retina.

light sensation.

3. The rate below which successive

4. Contain rhodopsin.

images are seen as separate images.

5. Can be measured by use of Snellen letter

charts.

Rods.

Visual threshold.

Cones.

Visual acuity.

Critical fusion frequency.

EMQ Question 387

For each visual disturbance A–E, select the most appropriate option from the following list.

1. A blind spot.

2. Inability to see in the dark.

3. Loss of vision.

4. A condition where visual images do not

5. Double vision.

fall on corresponding retinal points.

Strabismus.

Diplopia.

Amblyopia.

Scotoma.

Nyctalopia.

EMQ

164

Special senses – answers

Answers for 385

Option 5

Due to loss of lens elasticity with ageing. With increasing age, the lens loses

its elasticity, so decreasing the ability of the eye to accommodate for near vision.

Option 4

Causes reflex contraction of circular smooth muscle in the iris. If light is

shone on the retina, the circular ciliary muscles contract to decrease the size of the pupil
so decreasing spherical aberration by the lens.

Option 2

Determined by the maximum convexity the lens can attain. The near point is

the point nearest to the eye where the lens system can focus a sharp image. It depends on
the elasticity of the lens and is nearest in infancy and recedes with age.

Option 3

Usually involves contraction of the ciliary muscles. Accommodation for near

vision depends on contraction of the ciliary muscle to increase the convexity of the lens,
convergence of the axes of the eyes and constriction of the pupils.

Option 1

Normal vision. Emmetropia is the term describing normal refraction in the

eye. It contrasts with hypermetropia (long-sightedness) and myopia (short-sightedness).

Answers for 386

Option 4

Contain rhodopsin. Rhodopsin is responsible for vision in poor light. It

(Visual Purple) is the most sensitive visual pigment with a peak sensitivity to light at
505 nm.

Option 2

The minimum amount of light that elicits light sensation. In dark adaptation

the visual threshold falls.

Option 1

Contain the least light-sensitive pigments in the retina. The cones contain

three colour sensitive pigments and are responsible for colour vision and vision in bright
light.

Option 5

Can be measured by use of Snellen letter charts. The results are expressed as

a fraction – 20/20 (or 6/6) being normal; a fraction less than unity, e.g. 10/20 indicates
below normal acuity.

Option 3

The rate below which successive images are seen as separate images. Above

that rate the images fuse to provide a continuous image.

Answers for 387

Option 4

A condition where visual images do not fall on corresponding retinal points.

This is squint.

Option 5

Double vision. This is usually caused by problems in the control of the exter-

nal ocular muscles which interfere with the ability of the eyes to form images on corre-
sponding retinal points.

Option 3

Loss of vision. It may be partial or complete.

Option 1

A blind spot. Visual impairment with a scotoma depends on its location on

the retina. Central scotomas are more disabling than peripheral scotomas.

Option 2

Inability to see in the dark. Night blindness is seen where there is a deﬁ-

ciency of Vitamin A that is needed for the production of rhodopsin.

EMQ

Special senses – questions

165

EMQ Question 388

For each of the visual terms A–E, select the most appropriate option from the following list of
deﬁnitions.

1. Blindness in half of the visual ﬁeld.

2. Loss of central vision with normal

3. Continuous jerky movements of the

peripheral vision.

eyeballs.

4. People who can only distinguish between

5. Loss of peripheral vision with normal

two primary colours.

central vision.

Nystagmus.

Hemianopia.

Dichromats.

Central scotoma.

Macular sparing.

EMQ Question 389

For each of the structures concerned with sound transmission in the ear A–E, select the most
appropriate option from the list below.

1. Bulges out when the oval window

2. Dampens vibration of the oval window

membrane bulges in.

membrane.

3. Dampens vibrations of the tympanic

4. Located in the foramen ovale.

membrane.

5. Bulges in when the oval window bulges in.

Foot plate of stapes.

Tympanic membrane.

Tensor tympani muscle.

Stapedius muscle.

Round window.

EMQ Question 390

For each of the structures concerned with inner ear receptor organs A–E, select the most appro-
priate option from the list below.

1. The gelatinous partition of top of the 2. The sensory organ in the utricle.

crista that closes off the ampulla.

3. The membrane structure overlying the

4. The sensory organ in the semicircular

receptor cells in the organ of Corti.

canals.

5. The hair processes on receptor cells in the

inner ear.

Crista ampullaris.

Otolith organ.

Cupula.

Stereocilia.

Tectorial membrane.

EMQ

166

Special senses – answers

Answers for 388

Option 3

Continuous jerky movements of the eyeballs. These can occur normally

(physiological nystagmus) but are exaggerated in certain diseases affecting the cerebel-
lum.

Option 1

Blindness in half of the visual ﬁeld. Usually caused by a lesion in one optic

tract. A lesion affecting one optic nerve causes total blindness in that eye.

Option 4

People who can only distinguish between two primary colours. This is one

form of colour blindness; healthy people (trichromats) can distinguish between the three
primary colours.

Option 2

Loss of central vision with normal peripheral vision. This is due to damage

to the macula.

Option 5

Loss of peripheral vision with normal central vision. This is often seen in

patients with lesions affecting the occipital (visual) cortex.

Answers for 389

Option 4

Located in the foramen ovale. It is embedded in the foramen ovale mem-

brane.

Option 5

Bulges in when the oval window bulges in. Tympanic membrane movements

are transmitted by the auditory ossicles to the oval window.

Option 3

Dampens vibrations of the tympanic membrane. This muscle is attached to

the manubrium of the malleus and when it contracts reflexly in response to an incoming
sound, it tightens the tympanic membrane and damps its movements.

Option 2

Dampens vibration of the oval window membrane. The stapedius muscle is

attached to the stapes and pulls on it reflexly to dampen its movements in response to
incoming loud noise.

Option 1

Bulges out when the oval window membrane bulges in. The round window

lies where the scala tympani abuts on the middle ear and by bulging out when the stapes
footplate bulges in reduces the pressure changes with incoming sounds in the inner ear.

Answers for 390

Option 4

The sensory organ in the semicircular canals. Each semicircular canal has an

ampulla whose sense organ is stimulated by movement of endolymph caused by rotary
accelerations of the head in the three spatial planes in which the semicircular canals lie.

Option 2

The sensory organ in the utricle. These sensory organs are stimulated by

linear accelerations of the head that modify the pull of the otoliths on the hair cells of the
otolith organ.

Option 1

The gelatinous partition of top of the crista that closes off the ampulla.

When there is movement of fluid in the semicircular canals it causes deflections of the
cupula that alter the output of impulses from the underlying crista ampullaris.

Option 5

The hair processes on receptor cells in the inner ear. These rod-shaped struc-

tures protrude from the hair cells and cause generator potentials when they are deformed
by movement of endolymph.

Option 3

The membrane structure overlying the receptor cells in the organ of Corti.

This structure which overlies the organ of Corti may be involved in bending of hair cells
when the basilar membrane is made to vibrate with incoming sound waves.

EMQ

Special senses – questions

167

EMQ Question 391

For each of the structures concerned with hearing A–E, select the most appropriate option from
the list below.

1. A centre for auditory reflexes.

2. Separates scala in the inner ear.

3. Equalizes middle ear with

4. Responsible for bony conduction of

atmospheric pressure.

incoming sound waves.

5. Important in air conduction of incoming sound waves.

The basilar membrane.

The skull.

The auditory ossicles.

The Eustachian tube.

Inferior colliculi.

EMQ Question 392

For each of the structures concerned with taste sensation A–E, select the most appropriate
option from the list below.

1. Carries taste impulses serving the

2. Associated with bitter taste sensation.

sensation of sweetness.

3. Carries taste impulses serving the sensation

4. Associated with sweet taste sensation.

of bitterness.

5. Associated with salt taste sensation.

Taste buds at the back of the tongue.

Taste buds at the front of the tongue.

Taste buds at the side of the tongue.

The glossopharyngeal nerve.

The facial nerve.

EMQ Question 393

For each of the sensory pathways A–E, select the most appropriate option from the list below.

1. Third order sensory pathway from thalamus to the postcentral gyrus.
2. The tracts carrying proprioception impulses in ﬁrst order sensory neurones to the

nucleus gracilis and cuneatus.

3. A tract in the brainstem carrying sensory impulses to the thalamus.
4. A tract containing the second order sensory neurones carrying pain and temperature

sensation.

5. A tract containing the ascending second order neurones carrying touch and pressure

sensation.

Lateral spino-thalamic tract.

Thalamic radiation.

Medial (ventral) spino-thalamic tract.

Dorsal columns.

Medial lemniscus.

EMQ

168

Special senses – answers

Answers to 391

Option 2

Separates scala in the inner ear. The basilar membrane on which the organ

of Corti lies separates the scala media from the scala tympani.

Option 4

Responsible for bony conduction of incoming sound waves. If the middle ear

is completely destroyed by disease, some hearing ability remains as sound waves can be
conducted through the bone of the skull to the inner ear.

Option 5

Important in air conduction of incoming sound waves. The malleus, incus

and stapes form a good lever system to transmit sound waves from the tympanic mem-
brane to the round window without much attenuation.

Option 3

Equalizes middle ear with atmospheric pressure. The Eustachian tube con-

nects the middle ear to the pharynx so that the pressure on either side of the tympanic
membrane is about atmospheric.

Option 1

A centre for auditory reflexes. The cochlear nerve carries auditory impulses

from the organ of Corti to the inferior colliculi, centres for auditory reflexes.

Answers for 392

Option 2

Associated with bitter taste sensation. The taste buds sensing bitter tastes are

located in the vallate papillae in a V-shaped area on the back part of the upper surface of
the tongue.

Option 4

Associated with sweet taste sensation. Taste buds that sense sweet stimuli

are in the fungiform papillae on the dorsal surface towards the front of the tongue.

Option 5

Associated with salt taste sensation. The taste buds at the side of the tongue

respond to salt and sour taste stimuli.

Option 3

Carries taste impulses serving the sensation of bitterness. The glossopharyn-

geal nerve carries impulses from the posterior third of the surface of the tongue and thus
serves bitter taste sensation.

Option 1

Carries taste impulses serving the sensation of sweetness. The chorda tym-

pani branch of the facial nerve carries sensory impulses from the anterior two-thirds of
the tongue and thus serves the sensation of sweetness.

Answers for 393

Option 4

A tract containing the second order sensory neurones carrying pain and tem-

perature sensation. These tracts carry pain and temperature impulses from receptors on
the opposite side of the body to the thalamus.

Option 1

Third order sensory pathway from thalamus to the postcentral gyrus. In the

postcentral gyrus the sensory impulses generate conscious sensation.

Option 5

A tract containing the ascending second order neurones carrying touch and

pressure sensation. These tracts carry touch and pressure impulses from the opposite side
of the body to the thalamus.

Option 2

The tracts carrying proprioception impulses in ﬁrst order sensory neurones

to the nucleus gracilis and cuneatus. These tracts carry impulses from muscle spindles and
other receptors on the same side of the body that ascend in ﬁrst order sensory neurones
to the gracile and cuneate nuclei. From there second order neurones cross to the opposite
side of the body in the sensory decussation to join the medial lemniscus and ascend to the
thalamus.

Option 3

A tract in the brainstem carrying sensory impulses to the thalamus. This is

the common sensory pathway in the brainstem carrying all sensory impulses to the thal-
amus.

EMQ

Special senses – questions

169

EMQ Question 394

For each of the sensory disturbances A–E, select the most appropriate option from the list
below.

1. The gradual loss of hearing ability

2. The loss of ability to recognize objects by

with age.

touch.

3. Absence of smell sensation.

4. Night blindness.

5. A refractive error due to the cornea having different refractive power in the horizon-

tal and transverse planes.

6. A disorder of hearing where the patient complains of hearing abnormal noise.

Astereognosis.

Astigmatism.

Presbycusis.

Anosmia.

Tinnitus.

EMQ

170

Special senses – answers

Answers for 394

Option 2

The loss of ability to recognize objects by touch. This ability is a cortical

function and its loss suggests damage to the sensory cortex in the postcentral gyrus of the
parietal lobe.

Option 5

A refractive error due to the cornea having different refractive power in the

horizontal and transverse planes. This common refractive error is corrected by provision
of cylindrical lenses that make refraction in the vertical plane equal refraction in the hor-
izontal plane.

Option 1

The gradual loss of hearing ability with age. This affects about one third of

people over seventy and is probably due to cumulative damage to the hair cells in the
organs of Corti. It tends to be worse in people who have lived and worked in noisy envi-
ronments.

Option 3

Absence of smell sensation. As with hearing, sensitivity to smell stimuli

tends to decrease with age. Temporary anosmia is a feature of the common cold.

Option 6

A disorder of hearing where the patient complains of hearing abnormal

noise. The noise is described as ringing, buzzing, roaring etc.

EMQ

URINARY SYSTEM

171

MCQs

Questions 395–400

395. Hydrostatic pressure in renal glomerular capillaries

Is lower than pressure in efferent arterioles.

Rises when afferent arterioles constrict.

Is higher than in most capillaries at heart level.

Falls by 10 per cent when arterial pressure falls by 10 per cent.

Falls along the length of the capillary.

396. Tubular reabsorption of a filtered substance is likely to be active rather

than passive if its

Concentration in the tubular fluid is lower than in peritubular capillary blood.

Excretion is increased by cooling the kidney.

Renal clearance is lower than that of inulin.

Renal clearance rises at high plasma levels.

Urinary excretion rate:plasma concentration ratio is the same as for glucose.

397. The renal clearance of a substance

Is inversely related to its urinary concentration, U.

Is directly related to the rate of urine formation, V.

Is directly related to its plasma concentration, P.

Is expressed in units of volume per unit time.

Must fall in the presence of metabolic poisons.

398. In fluid in the distal part of the proximal convoluted tubule

Urea concentration is higher than in Bowman’s capsule.

pH is less than 6 when the kidneys are excreting an acid urine.

Glucose concentration is similar to that in plasma.

Osmolality is about 25 per cent that of glomerular ﬁltrate.

Bicarbonate concentration is lower than in plasma.

399. Renal tubules normally reabsorb

More water every hour than the entire plasma volume.

All ﬁltered HCO

⫺

in respiratory acidosis.

All ﬁltered amino acids.

All ﬁltered plasma proteins.

More K

⫹

than Cl

⫺

400. As plasma glucose concentration rises above normal, glucose

Filtration increases linearly.

Transport maximum T

increases linearly.

Clearance increases linearly.

Reabsorption increases and then levels off.

Excretion increases and then decreases.

MCQ

172

Urinary system – answers

Answers

395.

False

It must be higher to maintain blood flow.

False

The pressure drop across the afferent arterioles increases as they constrict.

True

The afferent arterioles offer relatively little resistance.

False

Redistribution of renal vascular resistance due to autoregulation tends to main-
tain glomerular hydrostatic pressure and hence ﬁltration.

True

Hydrostatic pressure falls due to vascular resistance; oncotic pressure rises due to
loss of protein-poor ﬁltrate; both these factors reduce ﬁltration pressure along the
length of the glomerular capillary.

396.

True

This suggests transportation into the blood against a concentration gradient.

True

Cooling impairs active metabolic processes.

False

This indicates reabsorption but not whether it is active (e.g. glucose) or passive
(e.g. urea).

True

This suggests saturation of a carrier system.

True

Anything ﬁltered in glomeruli and having zero clearance must be actively reab-
sorbed.

397.

False

It is directly related to urinary concentration.

True

Clearance tends to fall at low urinary flow rates.

False

It is inversely related to plasma concentration.

True

Clearance

⫽UV/P in units of volume/unit time.

False

It rises if the substance is normally reabsorbed by an active process.

398.

True

Due to reabsorption of water.

False

Acidiﬁcation occurs mainly in the distal convoluted tubule.

False

Most or all of the glucose is reabsorbed before the end of the proximal tubule.

False

Osmolality changes little in the proximal convoluted tubule.

True

Like glucose, HCO

⫺

is usually completely reabsorbed in the proximal tubule.

399.

True

About 99 per cent of the glomerular ﬁltrate (about 8 litres/hour).

True

This plus HCO

⫺

manufactured in the kidney compensates the respiratory acido-

sis.

True

These are ﬁltered but do not appear in normal urine.

True

Again some are ﬁltered but do not appear in urine.

False

About 20 times as much chloride as potassium is ﬁltered (this is the ratio of their
plasma concentrations).

400.

True

Filtration rate is directly proportional to concentration.

False

Transport maxima are constants.

False

It remains at zero until the T

is reached and then it rises linearly.

True

It levels off after T

glucose is reached.

False

It is initially zero and then rises linearly.

MCQ

Urinary system – questions

173

Questions 401–406

401. A substance is being secreted by the renal tubules if its

Clearance rate is greater than 250 ml/minute.

Concentration is higher in arterial than in renal venous blood.

Excretion rate is increased by tubular enzyme poisons.

Concentration rises along the proximal convoluted tubule.

Concentration in urine is greater than in plasma.

402. In the nephron, the osmolality of fluid in the

Tip of the loop of Henle is less than that of plasma.

Bowman’s capsules is less than that in the distal tubules.

Collecting duct rises when vasopressin is being secreted.

Proximal convoluted tubule rises along its length.

Medullary interstitium can exceed one osmole per litre.

403. Transport maximum (T

) – limited reabsorption of a substance implies

that its

Reabsorption is active.

Reabsorption is critically related to tubular transit time.

Reabsorption is complete below a certain threshold load.

Renal clearance falls with its plasma concentration.

Excretion rate is zero until its T

value is reached.

404. When a patient’s mean arterial blood pressure falls by 50 per cent

Renal blood flow falls by less than 10 per cent.

Glomerular ﬁltration falls by about 50 per cent.

There is an increase in the circulating aldosterone level.

Renal vasoconstriction occurs.

Urinary output ceases.

405. The cells of the distal convoluted tubule

Reabsorb about 50 per cent of the water ﬁltered by the glomeruli.

Secrete hydrogen ions into the tubular lumen.

Form NH

⫹

ions.

Reabsorb sodium in exchange for hydrogen or potassium ions.

Determine the ﬁnal composition of urine.

406. If, during an infusion of para-aminohippuric acid, peripheral venous

plasma PAH level is 0.02 mg/ml (not above renal threshold), urinary PAH
level is 16 mg/ml and urinary flow rate 1 ml/min, then the

PAH level in renal venous blood must exceed 0.02 mg/ml.

PAH level in renal arterial blood must be about 0.02 mg/ml.

PAH level in glomerular ﬁltrate must be about 0.02 mg/ml.

Renal plasma flow is nearer 800 than 1000 ml/minute.

Renal blood flow is nearer 1300 than 1500 ml/minute if the haematocrit is 0.40.

MCQ

174

Urinary system – answers

Answers

401.

True

A clearance value above the glomerular ﬁltration rate (about 140 ml/minute)
indicates secretion.

True

Some of the unﬁltered fraction must have been secreted.

False

This suggests that the substance is normally reabsorbed by an active process.

False

This can be explained by water reabsorption.

False

Again, this can be explained by a relatively greater reabsorption of water.

402.

False

This fluid is hypertonic because of countercurrent concentration.

False

Distal tubular fluid is hypotonic.

True

Vasopressin (ADH) promotes water, but not salt, reabsorption in collecting ducts.

False

The fluid remains isotonic with plasma.

True

It can be about four times that of plasma.

403.

True

limited reabsorption is one type of active tubular reabsorption.

False

This applies to the other type of active tubular reabsorption, gradient-time lim-
ited reabsorption.

True

As with glucose.

False

Clearance is zero at all levels below the threshold.

True

The concept applies also to amino acids and proteins.

404.

False

Autoregulation cannot compensate for such large falls.

False

It falls to about zero when glomerular capillary pressure falls below the sum of
intracapsular pressure plus plasma oncotic pressure – around 30–40 mmHg.

True

Due to release of renin and angiotensin formation, aldosterone is secreted.

True

Reflex sympathetic vasoconstriction due to greatly decreased baroreceptor stim-
ulation.

True

When glomerular ﬁltration stops, urinary output stops.

405.

False

About 80 per cent of the ﬁltered water is reabsorbed before it reaches the distal
tubules.

True

The rate is related to acid–base requirements.

True

By conversion of glutamine to glutamate; NH

is a buffer for the H

⫹

being

excreted.

True

⫹

secretion is related to the body’s acid–base balance.

False

Further modiﬁcation takes place in the collecting ducts.

406.

False

The renal venous blood level would be negligible.

True

Since PAH is excreted only by the kidneys, the PAH level in peripheral venous
blood determines the level entering the arterial system, and hence the renal arter-
ies.

True

Since PAH is freely ﬁltered.

True

Flow

⫽PAH clearance⫽UV/P⫽16⫻1/0.02⫽800 ml/minute.

True

Blood flow

⫽plasma flow/0.6⫽1333 ml/minute.

MCQ

Urinary system – questions

175

Questions 407–411

407. Renal blood flow falls

About 10 per cent when arterial pressure falls 10 per cent below normal.

About 5 per cent when metabolic activity in the kidney falls by 5 per cent.

During emotional stress.

After moderate haemorrhage.

Gradually from the inner medulla to the outer cortex per unit weight of tissue.

408. Urea

And glucose have similar molar concentrations in normal blood.

Concentration rises in tubular fluid as the glomerular ﬁltrate passes down the nephron.

Is actively secreted by the renal tubular cells into the tubular fluid.

Concentration in blood may rise ten-fold after a high protein meal.

Causes a diuresis when its blood concentration is increased.

409. Voluntary micturition

Depends on the integrity of a lumbar spinal reflex arc.

Is not possible after sensory denervation of the bladder.

Involves stimulation of the detrusor muscle in the bladder by autonomic sympathetic
nerves.

Is normally accompanied by some reflux of bladder contents into the ureters.

Is inhibited during ejaculation.

410. The proximal convoluted tubules

Reabsorb most of the sodium ions in glomerular ﬁltrate.

Reabsorb most of the chloride ions in glomerular ﬁltrate.

Reabsorb most of the potassium ions in glomerular ﬁltrate.

Contain juxtaglomerular cells which secrete rennin.

Contain the main target cells for antidiuretic hormone.

411. The renal clearance of

Inulin provides an estimate of glomerular ﬁltration rate.

Chloride increases after an injection of aldosterone.

PAH falls when the PAH load exceeds the T

for PAH.

Urea is lower than that of inulin.

Inulin is independent of its plasma concentration.

MCQ

176

Urinary system – answers

Answers

407.

False

Due to autoregulation, flow changes little with small changes in perfusion pres-
sure.

False

Normal renal blood flow is vastly in excess of its metabolic requirements.

True

Due to sympathetic vasoconstrictor nerves and circulating catecholamines.

True

A reflex response to the fall in blood pressure so caused.

False

Cortical flow is 10–20 times higher than medullary flow.

408.

True

Both are around 5 mmol/litre.

True

The urinary concentration of urea is many times that in plasma.

False

50 per cent of the ﬁltered urea is passively reabsorbed; the rise in tubular con-
centration can be explained by the reabsorption of water.

False

It rises but would not double in concentration.

True

It causes an osmotic diuresis.

409.

False

The reflex centres are in the sacral cord; their activity is modulated by higher
centres.

True

This breaks the reflex arc.

False

Parasympathetic nerves are motor to the detrusor muscle.

False

Valves where the ureters enter the bladder do not allow such reflux.

True

During ejaculation, sympathetic activity constricts the bladder neck sphincter and
prevents retrograde ejaculation of semen into the bladder.

410.

True

More than half of the ﬁltered sodium is actively absorbed in the proximal tubules.

True

Negatively charged chloride ions follow the positively charged sodium.

True

Most of the potassium is reabsorbed in the proximal tubule; some is re-excreted
in the distal tubules in exchange for sodium.

False

Rennin is an enzyme found in gastric juice that causes milk to clot. The juxta-
glomerular cells that secrete renin are found where the distal tubule makes con-
tact with the afferent arteriole.

False

This hormone acts mainly on distal parts of the nephron.

411.

True

Inulin is freely ﬁltered but not reabsorbed or secreted in the tubules; therefore the
amount excreted in the urine equals the amount ﬁltered at the glomerulus.

False

Aldosterone increases Na

⫹

and Cl

⫺

reabsorption and so reduces their clearance.

True

At high plasma levels, the T

for PAH is exceeded and PAH is not completely

cleared in one passage through the kidney.

True

About 60 compared with 120 ml/minute; half the ﬁltered urea is passively reab-
sorbed.

True

The amount ﬁltered is the amount excreted.

MCQ

Urinary system – questions

177

Questions 412–417

412. The collecting ducts in the kidney

Can actively transport water molecules into the urine.

Are the site of most of renal water reabsorption.

Are rendered impermeable to water by antidiuretic hormone (ADH).

Pass through a region of exceptional hypertonicity.

Determine to a large extent the ﬁnal osmolality of urine.

413. Aldosterone

Is a steroid hormone secreted by the adrenal medulla.

Production ceases following removal of the kidneys and their juxtaglomerular cells.

Production decreases in treatment with drugs which block angiotensin-converting
enzyme.

Secretion results in increased potassium reabsorption by the nephron.

Secretion results in a fall in urinary pH.

414. As fluid passes down the proximal convoluted tubule, there is a fall of

more than 50 per cent in the

Concentration of sulphate ions.

Concentration of sodium ions.

Concentrations of amino acids.

Concentration of potassium ions.

Rate of ﬁltrate flow in the tubules.

415. In normal healthy people, urinary

Speciﬁc gravity ranges from 1.010–1.020.

Osmolality ranges from 200–400 mosmol/litre.

Colour is due to small quantities of bile pigments.

pH falls as dietary protein rises.

Calcium excretion is increased by parathormone.

416. Aldosterone secretion tends to raise the volume of

Plasma.

Interstitial fluid.

Intracellular fluid.

Urine.

Cerebrospinal fluid.

417. The renal clearance of

Bicarbonate is similar to that of glucose.

PAH is nearer 600 than 1200 ml/minute in the average adult.

Creatinine provides an estimate of renal plasma flow.

Phosphate is decreased by parathormone.

Protein is normally zero.

MCQ

178

Urinary system – answers

Answers

412.

False

Active transport of water has not been described in the body.

False

More than half of the water in glomerular ﬁltrate is reabsorbed in the proximal
tubules.

False

Conversely, they are rendered permeable to water by ADH which induces water
channels in the collecting ducts.

True

Osmolality in the inner medullary interstitium can exceed 1 osmol/litre.

True

By determining the amount of water reabsorbed as the glomerular ﬁltrate passes
through the hypertonic medullary interstitium.

413.

False

It is a steroid as its name suggests but is secreted by the adrenal cortex.

False

Some aldosterone is secreted in response to ACTH secretion, high K

⫹

intake, heart

failure, etc. in addition to activity in the renin/angiotensin system.

True

ACE inhibitor drugs tend to reduce the level of angiotensin II which stimulates
the adrenal cortex to produce aldosterone.

False

It increases potassium secretion in exchange for sodium.

True

It increases H

⫹

secretion also in exchange for sodium.

414.

False

Sulphate concentration rises since relatively more water than sulphate is reab-
sorbed.

False

It is little changed, since similar proportions of sodium and water are reabsorbed.

True

These are completely reabsorbed by active transport.

False

Potassium is reabsorbed in proportion to water.

True

Due to reabsorption of about 80 per cent of the water.

415.

False

It may range from 1.004 to 1.040.

False

It may range from 100 to 1000 mosmol/litre.

False

It is due to ‘urochrome’, a pigment of uncertain origin.

True

Dietary proteins lead to acid residues such as sulphates and phosphates.

True

More calcium is ﬁltered due to the raised blood level, so more is excreted.

416.

True

By retention of sodium chloride and water in the extracellular fluid compartment.

True

This, like plasma, is a subcompartment of the extracellular fluid.

False

The sodium chloride/water retention is conﬁned to the extracellular compart-
ment.

False

It reduces it by retaining salt and water.

False

CSF is a secretion classiﬁed as transcellular fluid; it is not a subcompartment of
ECF.

417.

True

Both are usually totally reabsorbed so their renal clearance is about zero.

True

PAH clearance is a measure of renal plasma flow, not renal blood flow.

False

It provides an estimate of the glomerular ﬁltration rate since the amount ﬁltered
is close to the amount excreted.

False

Phosphate clearance is increased by parathormone and lowers the blood phos-
phate level.

True

Small amounts of protein are ﬁltered but reabsorbed.

MCQ

Urinary system – questions

179

Questions 418–423

418. Potassium

Is actively secreted in the distal convoluted tubule.

Is reabsorbed in the proximal convoluted tubule.

Deﬁciency favours hydrogen ion secretion in the distal tubule.

Excretion is determined largely by potassium intake.

Blood levels tend to rise in patients with acute renal failure taking a normal diet.

419. Secretion of renin

Occurs in the stomach during infancy.

Is stimulated by the hormone angiotensin I.

Leads to raised levels of angiotensin II in the blood.

Is stimulated by a fall in extracellular fluid volume.

Inhibits ACTH secretion by the pituitary gland.

420. In chronic renal failure

Glomerular ﬁltration rate may fall by 70 per cent before the condition gives rise to
symptoms.

The speciﬁc gravity of the urine tends to be elevated, e.g. about 1.030.

Blood P

tends to be low.

Ionized calcium levels in the blood tend to be high.

Anaemia is common.

421. Diabetes insipidus (deficiency of antidiuretic hormone) causes a fall in

the

Osmolality of the urine.

Reabsorption of water from the proximal tubules.

Extracellular but not intracellular fluid volume.

Extracellular fluid osmolality.

Intracellular fluid osmolality.

422. The cystometrogram shows

A plot of bladder pressure on the ordinate axis against bladder volume on the abscissa.

Little rise in pressure with rise in volume at low bladder volumes.

A steep rise in pressure when volume rises above 100 ml.

That females generate higher pressures during micturition than males.

That patients with chronic urinary tract obstruction can generate higher than normal
micturition pressures.

423. Treatment with an aldosterone antagonist causes a fall in

Urine volume.

Body potassium.

Body sodium.

Blood volume.

Blood viscosity.

MCQ

180

Urinary system – answers

Answers

418.

True

In exchange for sodium ions.

True

It is reabsorbed passively down the gradient created by Na

⫹

and H

O reabsorp-

tion.

True

Potassium and hydrogen compete for secretion in exchange for sodium.

True

Thus potassium balance is maintained.

True

In acute renal failure, the failure to excrete the potassium intake leads to high
blood levels which can compromise the performance of the heart.

419.

False

Rennin is the enzyme secreted by infant’s gastric mucosa which curdles milk.

False

Renin promotes angiotensin I formation from a circulating precursor.

True

Angiotensin I is converted to angiotensin II by a converting enzyme in the lungs.

True

Renin’s action helps to restore this volume.

False

There is no direct feedback between the two systems.

420.

True

The kidneys have a large functional reserve.

False

Renal ability to concentrate urine is impaired; the range of speciﬁc gravity
decreases, converging towards that of protein-free plasma, 1.010.

True

Poor excretion of acid residues causes metabolic acidosis which stimulates ven-
tilation.

False

Ionized calcium levels fall due to retention of phosphate ions and failure of renal
activation of vitamin D.

True

Due mainly to deﬁciency of erythropoietin.

421.

True

Due to failure of the kidneys to reabsorb sufﬁcient water.

False

Reabsorption of water in proximal tubules is normal since it depends on the
active reabsorption of sodium; reabsorption in the collecting ducts is affected.

False

Both fluid compartments are depleted in volume.

False

It rises due to depletion of water but not salt.

False

Both compartments show the same raised osmolality; osmotic gradients are effec-
tive in moving water at cell membranes.

422.

True

Bladder pressure is measured while known volumes of fluid are run into it.

True

An example of receptive relaxation like that seen in the stomach.

False

The deflection usually occurs when around 500 ml is introduced.

False

The male urinary tract offers a higher ‘peripheral resistance’.

True

The increased work load causes muscular hypertrophy which allows generation
of higher micturition pressures.

423.

False

It increases due to increased salt and water loss.

False

Body potassium rises since aldosterone normally increases its excretion.

True

Due to decreased sodium reabsorption.

True

Due to decreased extracellular fluid volume.

False

The viscosity increases as the haematocrit increases.

MCQ

Urinary system – questions

181

Questions 424–429

424. Dialysis fluid used in the treatment of renal failure should contain the

normal plasma levels of

Urea.

Potassium.

Osmolality.

Plasma proteins.

Hydrogen ions.

425. Long-standing obstruction of the urethra may cause

Enlargement of the prostate gland.

Hypertrophy of the bladder muscle.

Dilation of the ureters.

Reduction of the glomerular ﬁltration rate.

An increase in residual volume in the bladder.

426. Emptying of the bladder may be less effective if

The sympathetic nerves carrying afferent information from bladder to spinal cord are
cut.

The pelvic nerves are cut.

Anticholinergic drugs are administered.

Alpha-adrenergic receptor antagonists are administered.

Beta-adrenergic receptor agonists are administered.

427. Renal transplantation for chronic renal failure in adults should

Be covered by immunosuppression even when the donor is the recipient’s identical twin.

Raise postoperative glomerular ﬁltration rate to the 10–20 ml/minute level.

Correct abnormal calcium metabolism.

Correct anaemia.

Abolish the need for further renal dialysis.

428. Drugs which interfere with active transport of sodium in the proximal

tubule tend to increase

Urine production.

Plasma osmolality.

Chloride excretion.

Interstitial fluid volume.

Plasma speciﬁc gravity.

429. A drug which inhibits carbonic anhydrase decreases

Bicarbonate formation and reabsorption in the kidney.

Plasma bicarbonate levels.

Blood pH.

Urinary loss of potassium ions.

Urinary volume and pH.

MCQ

182

Urinary system – answers

Answers

424.

False

It should be urea-free to provide a high concentration gradient for urea loss.

False

It should be lower to favour loss of potassium, which is elevated in renal failure.

False

It should be higher to reduce extracellular fluid volume and hence blood pres-
sure.

False

Fluid transfer is governed by hydrostatic pressure and crystalloid osmolality gra-
dients, not by colloid osmotic pressure gradients.

True

It should be buffered to prevent large pH changes.

425.

False

Prostatic enlargement is a cause, not a consequence, of urethral obstruction.

True

Due to the increased work it has to do.

True

Long-standing obstruction leads to urinary reflux when the uretero-vesical
valves become incompetent.

True

Back-pressure in the ureters is transmitted to the nephrons and raises capsular
pressure in the glomerulus.

True

This encourages urinary tract infection.

426.

False

Sympathetic trunks carry pain afferents, not stretch receptor afferents to the cord.

True

These carry the stretch receptor afferents from the bladder and parasympathetic
motor ﬁbres to the bladder; the micturition reflex is lost.

True

These block the parasympathetic motor ﬁbres to the detrusor muscle.

False

Alpha receptor antagonists relax bladder sphincter muscle: they are used to facil-
itate bladder emptying in patients with benign prostatic hypertrophy.

True

They tend to relax the detrusor muscle.

427.

False

Donor and recipient have identical genes and immunological characteristics.

False

It should raise it to near normal, 120–150 ml/minute.

True

This reverses the tendency to demineralization of bone.

True

The transplanted kidney should supply the missing erythropoietin.

True

A healthy transplanted kidney should return all aspects of renal function to
normal.

428.

True

By increasing salt and hence water loss.

False

This is regulated by ADH and the collecting ducts.

True

Chloride passively follows the sodium being excreted.

False

This falls with the loss of salt and water.

True

Due to concentration of the proteins by removal of water.

429.

True

Carbonic anhydrase in tubular cells catalyses the combination of CO

and H

O to

form H

which ionizes into H

⫹

and HCO

⫹

ions.

True

This is determined mainly by renal bicarbonate formation.

True

This falls as the plasma bicarbonate level falls.

False

More K

⫹

is secreted by the tubules in exchange for sodium since there are fewer

⫹

ions to compete with K

⫹

in the sodium/potassium exchange pump.

False

Failure to reabsorb HCO

results in an osmotic diuresis of alkaline urine.

MCQ

Urinary system – questions

183

Questions 430–434

430. A patient with chronic renal failure usually has an increased

Blood urea.

Blood uric acid.

Creatinine clearance.

Acid–base disturbance when he or she vomits.

Acid–base problem on a high protein diet.

431. Cutting the sympathetic nerves to the bladder may cause

Difﬁculty in emptying the bladder.

Loss of tone in the internal sphincter of the bladder.

Loss of tone in the external sphincter of the bladder.

Loss of pain sensation in the bladder.

Infertility in the male.

432. Sudden (acute) renal failure differs from gradual (chronic) renal failure

in that

Potassium retention tends to be more severe.

Blood urea levels tend to be higher.

Depression of bone marrow activity is unlikely to occur.

Metabolic acidosis is usually not a problem.

Dietary protein restriction is unnecessary.

433. In the treatment of someone with progressive renal failure

Protein should be excluded from the diet.

Water intake should be restricted to about 0.5 litre/day.

The diet should be potassium-free.

Adequate dietary iron intake prevents anaemia.

The caloriﬁc value of the diet should be gradually reduced.

434. A long-standing increase in arterial P

CO2

(respiratory acidosis) leads to an

increase in

Renal bicarbonate formation.

Urinary ammonium salts.

Plasma potassium concentration.

The ratio of monohydrogen to dihydrogen phosphate in urine.

Urinary bicarbonate excretion.

MCQ

184

Urinary system – answers

Answers

430.

True

A high blood urea is usually the ﬁrst sign of renal failure.

True

As with other end products of protein digestion.

False

Creatinine clearance, a measure of GFR, is reduced in proportion to the severity
of the renal failure.

False

Loss of the acid vomitus would improve the typical acidosis.

True

Proteins are a major source of the acid residues and toxic substances which accu-
mulate in renal failure.

431.

False

It may cause increased frequency of micturition.

True

Sympathetic activity tends to raise sphincter tone.

False

This sphincter is supplied by somatic nerves.

True

Afferent pain ﬁbres run with the sympathetic nerves.

True

Sympathetic ﬁbres are necessary for closure of the internal sphincter of the blad-
der during ejaculation to prevent reflux of seminal fluid.

432.

True

Potassium retention is one of the greatest hazards of acute renal failure and may
cause death from myocardial depression.

False

The blood urea level is determined by the severity of the condition, not by its rate
of progression.

False

Both may depress the marrow and lower RBC, polymorph and platelet counts.

False

Both impair renal bicarbonate production.

False

Protein restriction is advisable in both cases.

433.

False

A low protein diet is helpful but some protein is needed to provide essential
amino acids for tissue maintenance.

False

This would not cover insensible loss plus urine volume; also in some stages of
renal failure urine volume is increased.

False

Potassium intake is required to replace potassium lost in urine.

False

Anaemia is due to bone marrow depression, not iron deﬁciency.

False

Sufﬁcient dietary intake is needed to prevent excessive tissue protein catabolism.

434.

True

This raises plasma bicarbonate to compensate for the raised P

in respiratory

acidosis.

True

In acidosis, tubular cells excrete more to buffer the additional H

⫹

ions being

secreted.

True

The increased secretion of H

⫹

ions in exchange for Na

⫹

results in decreased secre-

tion of K

⫹

ions.

False

The ratio decreases as hydrogen ions are taken up by the phosphate buffer
system.

False

The urine remains bicarbonate-free.

MCQ

URINARY SYSTEM

185

EMQs

Questions 435–444

EMQ Question 435

For each case of bladder abnormality A–E, select the most appropriate option from the follow-
ing list.

1. Atonic bladder with overflow.

2. Stress incontinence.

3. Chronic prostatic obstruction.

4. Acute retention of urine.

5. Automatic bladder.

6. Bladder diverticulum.

A 30-year-old woman with three children complains of wetting herself during coughing
and sneezing.

A 20-year-old woman had a spinal injury two years ago as a result of diving into shal-
low water. She has lost normal control of the urinary bladder but can initiate micturi-
tion when the bladder is fairly full by pressing on the lower abdomen.

An 80-year-old man has been admitted to hospital as an emergency complaining of
lower abdominal pain and inability to pass urine for 12 hours. In recent months he had
noticed that the urinary stream was poor. On admission he has abnormal dullness to
percussion over his lower abdomen and on rectal examination, enlargement of the pros-
tate.

A 29-year-old man was admitted to hospital following a neck injury and paralysis of
the legs. On the day after admission, knee and ankle jerks cannot be elicited and he is
incontinent of urine.

A 75-year-old man complains of frequency of micturition and poor flow; his cystome-
trogram shows raised bladder pressures in the contracted state and an abnormally high
residual volume.

EMQ Question 436

For each of the functional descriptions A–E, select the most appropriate option from the fol-
lowing list of regions of the nephron and urinary tract.

1. Proximal convoluted tubule.

2. Distal convoluted tubule.

3. Thin limb of loop of Henle.

4. Thick limb of loop of Henle.

5. Collecting duct.

6. Ureter.

7. Bladder.

8. Urethra.

The site of the ﬁnal major adjustment of the pH of the ﬁltered fluid.

A region where reabsorption is associated with the presence of microvilli on the luminal
cell surface.

A region where the passage of a calculus (stone) is associated with severely painful
smooth muscle contractions referred to one side of the lower part of the trunk.

The site of the ﬁnal major adjustment of the ammonium content of the ﬁltered fluid.

The site of the ﬁnal major adjustment of the osmolality of the ﬁltered fluid.

EMQ

186

Urinary system – answers

Answers for 435

Option 2

Stress incontinence. During coughing and sneezing intrathoracic and intra-

abdominal pressure is raised. In the presence of impaired sphincter action at the bladder
outlet, a common consequence of damage during delivery, the raised pressure can expel
some urine from the bladder. Laughing may have a similar effect.

Option 5

Automatic bladder. The patient had a spinal injury which has led to loss of

bladder control. Such injuries isolate the micturition centre in the sacral cord from higher
centre control. In such patients the bladder can empty automatically when distended by
means of the bladder stretch reflex centred in the sacral cord. Pressure on the abdomen
can initiate the reflex at a convenient time before it occurs automatically.

Option 4

Acute retention of urine. In elderly men, prostatic enlargement leads to pro-

gressive compression of the prostatic urethra. This leads to increasing resistance to flow
so that the urinary stream is poor. If the obstruction becomes complete so that micturition
is impossible, the bladder becomes painfully distended.

Option 1

Atonic bladder with overflow. This is another case of spinal injury isolating

the micturition centre in the sacral cord from higher centre control. However, in the acute
phase that comes on immediately and lasts for some weeks after the injury, the patient
usually shows a complete absence of spinal stretch reflexes below the level of the lesion
spinal shock. The micturition stretch reflex is abolished so that the bladder loses tone,
becomes distended and leaks uncontrollably due to the high pressure in the passively dis-
tended organ. Catheterization is important, to prevent damage to the bladder by such
over-stretching.

Option 3

Chronic prostatic obstruction. This is another case of prostatic obstruction

but without acute retention of urine. Gradual narrowing of the prostatic urethra raises the
urethral resistance which the bladder must overcome. Hypertrophy of the bladder wall
occurs (as in the left ventricle in systemic hypertension), hence bladder pressure during a
micturating cystometrogram (record of bladder pressure versus volume) is increased. As in
the failing heart, the bladder muscle fails to empty as completely as usual.

Answers for 436

Option 2

Distal convoluted tubule. Cells here have the ability to secrete hydrogen ions

until the luminal pH has fallen to 4–5.

Option 1

Proximal convoluted tubule. This is the major site for reabsorption, which is

facilitated by microvilli similar in many respects to those in the small intestine.

Option 6

Ureter. Passage of a calculus here is associated with the severe pain of renal

colic, referred to one or other loin.

Option 2

Distal convoluted tubule. These cells form and secrete ammonia to buffer

hydrogen ions secreted in the same region, especially when the rate of hydrogen ion secre-
tion is high; this prevents luminal pH from falling below 4.

Option 5

Collecting duct. Depending on the circulating level of anti-diuretic hormone,

the osmolality of the ﬁltrate rises along the collecting duct, to a maximum about four
times that of plasma.

EMQ

Urinary system – questions

187

EMQ Question 437

For each urinary solute A–E, select the most appropriate option from the following list of con-
centrations to be found in the urine of healthy people.

1. Always greater than in plasma.

2. Always less than in plasma.

3. Always the same as in plasma.

4. Can be less than or greater than in plasma.

Sodium.

Hydrogen ions.

Potassium ions.

Urea.

Para-aminohippurate (PAH).

EMQ Question 438

For each description A–E, related to glomerular ﬁltration, select the most appropriate option
from the following list of pressures.

1. 0 mmHg.

2. 5 mmHg.

3. 10 mmHg.

4. 15 mmHg.

5. 20 mmHg.

6. 30 mmHg.

7. 40 mmHg.

8. 50 mmHg.

9. 100 mmHg.

The pressure drop along the glomerular capillaries when the pressure at the end of the
afferent arterioles is 60 mmHg and that at the start of the efferent arterioles is
40 mmHg.

The net ﬁltration pressure from capillary lumen to Bowman’s capsule when capillary
pressure is 60 mmHg, the plasma protein oncotic pressure is 25 mmHg and the capsular
pressure is 15 mmHg.

The net ﬁltration pressure when capillary pressure is 35 mmHg, oncotic pressure
25 mmHg and capsular pressure 5 mmHg.

The capillary pressure which would exactly balance a plasma protein oncotic pressure of
20 mmHg.

A capsular pressure at which flow distally along the nephron would not occur.

EMQ Question 439

For each mechanism A–E related to renal handling of plasma solutes, select the most appro-
priate option from the following list of nephron functions.

1. Active tubular secretion.

2. Passive tubular secretion.

3. Active tubular reabsorption.

4. Passive tubular reabsorption.

5. Glomerular ﬁltration.

The mechanism whereby healthy people avoid having glucose in the urine (glycosuria).

The mechanism whereby urea has a lower clearance than creatinine.

The mechanism whereby around 99 per cent of the ﬁltered water is not lost in the urine.

The mechanism whereby the distal convoluted tubules eliminate excess hydrogen ions
from the body.

The only mechanism whereby the ideal substance for measuring the glomerular ﬁltra-
tion rate is eliminated from the body by the kidneys.

EMQ

188

Urinary system – answers

Answers for 437

Option 4

Can be less than or greater than in plasma. The plasma sodium level is

around 140 mmol per litre; with a low sodium intake of 50 mmol per day and a urinary
volume of one litre, the sodium concentration would be 50 mmol per litre; with a fairly
high sodium intake of 250 mmol per day and the same urinary volume, the concentration
would be 250 mmol per litre.

Option 4

Can be less than or greater than in plasma. Plasma pH is around 7.4; uri-

nary pH can vary from less than 5 to around 8.

Option 1

Always greater than in plasma. The intakes and outputs of potassium are of

a similar order to those given for sodium, so to maintain balance, the urinary concentra-
tions are also similar to those of sodium; however the plasma potassium concentration is
only about 4 mmol per litre.

Option 1

Always greater than in plasma. About 99 per cent of ﬁltered water is reab-

sorbed, but only about half of the ﬁltered urea.

Option 1

Always greater than in plasma. Not only is all the ﬁltered PAH excreted

(compare urea above), but, provided the tubular maximum is not exceeded, all the PAH
reaching the kidney is also excreted.

Answers for 438

Option 5

20 mmHg. This is similar to the pressure drop along systemic capillaries

when pressure at the arteriolar end is 35 mmHg and that at the venous end is 15 mmHg.

Option 5

20 mmHg. This would represent the situation at the proximal ends of the

glomerular capillaries; further along the capillaries, their hydrostatic pressure falls, while
the oncotic pressure rises as protein-poor fluid is ﬁltered; both factors reduce the ﬁltra-
tion pressure.

Option 2

5 mmHg. This would represent the situation in a patient with serious hypo-

tension (due, for example, to haemorrhage), just before ﬁltration pressure dropped to zero
when no further urine could be formed (anuria).

Option 5

20 mmHg. With this capillary pressure, ﬁltration would not occur; without

any flow, capsular pressure would fall to near zero.

Option 1

0 mmHg. Like capillaries, nephrons need a pressure drop along them to

permit flow distally.

Answers for 439

Option 3

Active tubular reabsorption. Reabsorption of glucose in the proximal convo-

luted tubules by a carrier mechanism relies on active reabsorption of sodium ions.

Option 4

Passive tubular reabsorption. Urea, like creatinine, is freely ﬁltered, but,

whereas virtually all the creatinine remains in the tubular lumen, about half the ﬁltered
urea passively diffuses back into the renal capillaries.

Option 4

Passive tubular reabsorption. Water follows absorbed solutes, particularly

sodium and chloride ions, passively by osmosis, as they are reabsorbed into the capillar-
ies.

Option 1

Active tubular secretion. An active pump exchanges absorbed sodium for

secreted potassium and hydrogen ions.

Option 5

Glomerular ﬁltration. The ideal substance for measuring glomerular ﬁltra-

tion rate is freely ﬁltered and neither absorbed from nor secreted into the tubules in any
way; inulin and creatinine are close to the ideal.

EMQ

Urinary system – questions

189

EMQ Question 440

For each of the hormonal actions A–E related to the kidney, select the most appropriate option
from the following list of hormones.

1. Aldosterone.

2. Antidiuretic hormone.

3. Cortisol.

4. Glucagon.

5. Insulin.

6. Parathormone.

7. Renin.

8. Erythropoietin.

An action that prevents glucose being lost in the urine of healthy people.

An action that decreases the renal clearance of sodium and thereby increases the extra-
cellular volume.

An action that promotes the formation of angiotensin I.

An action that lowers extracellular phosphate by increasing the renal clearance of phos-
phate.

An action that tends to lower both intracellular and extracellular osmolality.

EMQ Question 441

For each aspect of the treatment of renal failure by haemodialysis or peritoneal dialysis A–E,
select the best matching option from the following list of problems caused by renal failure.

1. Raised blood urea.

2. Abnormal arterial blood pressure.

3. Abnormal cardiac rhythms.

4. Hyperventilation.

5. Anaemia.

6. Impaired consciousness.

Removal of a variety of toxins, many unidentiﬁed, and correction of a variety of meta-
bolic disturbances.

Dialysing with fluid with a potassium level well below the normal plasma value.

Manipulating pressures and osmolalities in the dialysis fluid to reduce or increase the
patient’s body fluid content.

Dialysing with fluid with a higher pH than the normal plasma level.

Dialysing to lower the osmolality of the body fluids, irrespective of any change in elec-
trolytes.

EMQ Question 442

For each of the functional regions in the kidneys mentioned in A–E below, select the most
appropriate option for the parts of the kidney associated with that function from the follow-
ing list (outer medullary means beside the cortex and inner medullary means beside the renal
pelvis).

1. Proximal convoluted tubule.

2. Distal convoluted tubule.

3. Thin limb of loop of Henle.

4. Thick limb of loop of Henle.

5. Collecting duct.

6. Outer medullary interstitial fluid.

7. Middle medullary interstitial fluid.

8. Inner medullary interstitial fluid.

A region where the osmolality is actively reduced to around one third of the plasma
value.

A region where the osmolality is around twice the plasma value.

A region where the osmolality is around three to four times the plasma value.

A region where an energy substrate is reabsorbed by a carrier mechanism linked to
active reabsorption of sodium ions, similar to that in the enterocytes of the small intes-
tine.

A region where most of the ﬁltered bicarbonate is ‘reabsorbed’.

EMQ

190

Urinary system – answers

Answers for 440

Option 5

Insulin. Insulin, by favouring rapid entry of absorbed glucose into cells for

conversion to glycogen, normally keeps the blood glucose level below the renal threshold
for glucose excretion.

Option 1

Aldosterone. This hormone favours reabsorption of ﬁltered sodium, thereby

decreasing its clearance. The reabsorbed sodium is accompanied by chloride (following the
electrical gradient) and water (following the osmotic gradient); all these are distributed
mainly extracellularly, adding to the extracellular volume.

Option 7

Renin. This hormone acts on the circulating precursor, angiotensinogen to

form angiotensin I.

Option 6

Parathormone. This hormone stimulates the release of calcium and phos-

phate from bone; it also increases phosphate clearance by decreasing the reabsorption of
ﬁltered phosphate from the tubules.

Option 2

Antidiuretic hormone. This hormone increases reabsorption of water from

the collecting ducts; as water enters the extracellular fluid its osmolality decreases; the
higher intracellular osmolality draws over half this water into cells, restoring osmotic
equality of the intra- and extracellular fluids.

Answers for 441

Option 6

Impaired consciousness. Drowsiness and coma are related to a variety of dis-

turbances; dialysis reduces toxins by creating a gradient for passive diffusion, it can also
correct electrolyte and acid–base disturbances.

Option 3

Abnormal cardiac rhythms. Although these too are related to a variety of

disturbances, a very high extracellular/plasma potassium level is the major cause.

Option 2

Abnormal arterial blood pressure. The pressure may be too high or too low;

in both cases it may be corrected by increasing or decreasing extracellular and hence
blood volume; this may be done by ‘sucking’ fluid out of the patient’s blood by a raised
dialysate osmolality or by lowering the dialysing equipment (or drainage bag with perito-
neal dialysis) to remove fluid by gravity.

Option 4

Hyperventilation. Hyperventilation is a sign of serious acidosis, so the pH of

the dialysate fluid should be increased.

Option 1

Raised blood urea. A raised urea raises total osmolality; as an extreme

example, a rise of 30 mmol per litre would increase the normal osmolality (around
290 mosmol/kg) by just over 10 per cent; having the dialysate fluid free of urea allows a
gradient for diffusion out of the patient’s blood.

Answers for 442

Option 4

Thick limb of loop of Henle. This is where salt is actively pumped from the

tubular lumen, without water following, so the tubular fluid becomes markedly hypotonic;
in the absence of anti-diuretic hormone the fluid remains hypotonic as it enters the renal
pelvis to become urine.

Option 7

Middle medullary interstitial fluid. The medullary interstitium shows a gradient

normal osmolality to severe hyperosmolality across the medulla from renal cortex to pelvis.

Option 8

Inner medullary interstitial fluid. This is the last region the collecting ducts tra-

verse, so if they are in a state of permeability to water due to the presence of antidiuretic hor-
mone most of the water is drawn out of the duct lumen and the urine is very concentrated.

Option 1

Proximal convoluted tubule. In both gut and kidney the two key body

requirements, glucose and sodium, are avidly absorbed/reabsorbed into the body.

Option 1

Proximal convoluted tubule. The major buffer, bicarbonate, is also conserved

at this stage, by a fairly complex process involving active secretion of hydrogen ions into
the lumen; the quotation marks are used because the bicarbonate entering the renal cap-
illaries has been generated in the tubule cells; the secreted hydrogen ions join with the ﬁl-
tered bicarbonate to generate water and carbon dioxide molecules which are lost in the
crowd.

EMQ

Urinary system – questions

191

EMQ Question 443

For each ﬁnding A–E related to renal transplantation, where both donor and recipient are
adult, select the most appropriate variable related to that ﬁnding from the following list.

1. Glomerular ﬁltration rate.

2. Renal plasma flow.

3. Brainstem death.

4. Persistent vegetative state.

5. Tissue compatibility.

6. Coma due to drug overdose.

7. Immunological rejection.

8. Erythropoietin.

9. Renin.

10. Aldosterone.

Prior to removal of the donor kidney, it had been established that the unconscious, arti-
ﬁcially ventilated donor had persistently absent corneal and pupillary reflexes, there
was no eye movement response to ice cold water in the external auditory meatus, nor
was there any ventilatory response to carbon dioxide when the donor was temporarily
disconnected from the ventilator.

A careful comparison of recipient and donor showed that their cells share an encourag-
ing number of common antigens.

A month after transplantation the creatinine clearance is reported to be 85 ml/minute,
which is regarded as satisfactory.

On the same occasion the para-aminohippurate clearance is reported to be
55 ml/minute, which does not seem compatible with the result reported in (C).

On a later occasion the patient is found to have a blood haemoglobin level of
143 g/litre, whereas prior to renal transplantation and while maintained satisfactorily on
dialysis, the level was usually around 110 g/litre.

EMQ Question 444

For each aspect of renal function outlined A–E, select the most appropriate option from the
following list of renal cellular contents or activities.

1. Carbonic anhydrase.

2. Renin.

3. Erythropoietin.

4. Active exchange of sodium for hydrogen

5. Passive Na

⫹

exchange.

ions.

6. Active sodium reabsorption.

7. Active chloride reabsorption.

8. Water channels.

When a patient is deﬁcient in both hydrogen and sodium ions due to vomiting gastric
contents, renal function tends to make the alkalosis worse.

When a patient is deﬁcient in extracellular fluid, adrenal cortical hormones help to
restore its volume.

The loop of Henle contains cells which lead to a remarkably high osmolality in parts of
the renal medulla.

Certain renal cells can sense the oxygen content of arterial blood and control the blood
haemoglobin level.

A high level of antidiuretic hormone leads to a low urinary volume.

EMQ

192

Urinary system – answers

Answers for 443

Option 3

Brainstem death. The reflex responses mentioned are all mediated through

the brainstem and their persistent absence suggests death of the brain stem and hence of
the brain since the brain stem is the least sensitive part of the brain; brainstem function
is retained in the persistent vegetative state. Drug-induced coma is potentially reversible
and organ donation is thus not considered.

Option 5

Tissue compatibility. Tissue typing is analogous to but involves more factors

than determining blood group; shared antigens reduce the risk of transplant rejection.

Option 1

Glomerular ﬁltration rate. Creatinine is freely ﬁltered but not appreciably

reabsorbed or secreted, so its clearance is a practical indicator of glomerular ﬁltration rate.
This result, over half the value for two normal kidneys, will provide excellent renal func-
tion. The value tends to rise in the weeks after transplantation, as the disturbances asso-
ciated with the upheaval of transplantation settle down. In addition, the kidney tends to
hypertrophy, as would happen in someone who had one kidney removed with the other
one normal.

Option 2

Renal plasma flow. Para-aminohippurate is normally completely eliminated

from the circulation as it passes through the kidney, so indicates the renal plasma flow.
With a normal haematocrit, the result would indicate a renal blood flow of 100 ml/minute,
less than 10 per cent of normal and inconsistent with the above good creatinine clearance.

Option 8

Erythropoietin. Dialysis can correct many disturbances of renal failure, but

the lack of erythropoietin means the patient is subject to anaemia; the transplanted kidney
provides adequate erythropoietin for a normal haemoglobin level.

Answers for 444

Option 4

Active exchange of sodium for hydrogen ions. Stimulation of this pump to

retain sodium also favours secretion of hydrogen ions, making the alkalosis worse. In
addition, such patients are usually also short of potassium (lost with the vomited fluid)
and this is made worse since potassium and hydrogen ions compete for the exchange. This
condition is hypokalaemic alkalosis and the cure is to give intravenous sodium plus a safe
supplement of potassium.

Option 6

Active sodium reabsorption. As well as the above exchange, sodium absorp-

tion can be balanced electrically by chloride absorption; water follows by osmosis to
restore the extracellular fluid volume.

Option 7

Active chloride reabsorption. It has been shown that the loop of Henle

actively reabsorbs chloride, which is balanced electrically by sodium (reverse of above);
in this case water cannot follow, so the lumen becomes hypotonic and the interstitium
hypertonic.

Option 3

Erythropoietin. Active tubular cells become hypoxic when perfused with

anaemic blood; this leads to synthesis of erythropoietin which stimulates the red bone
marrow.

Option 8

Water channels. Antidiuretic hormone induces these, so that the hypertonic

renal medullary interstitium can osmotically draw water out of the collecting ducts, leav-
ing a small volume of concentrated fluid to pass to the bladder.

EMQ

ENDOCRINE SYSTEM

193

MCQs

Questions 445–450

445. In plasma, the half-life of

A hormone is half the time taken for it to disappear from the blood.

Insulin is between ﬁve and ten hours.

Thyroxine is longer than that of adrenaline.

Thyroxine is longer than that of triiodothyronine.

Noradrenaline is longer than that of acetylcholine.

446. During sleep there is a fall in the circulating level of

Cortisol.

Insulin.

Adrenaline.

Antidiuretic hormone.

Growth hormone.

447. Adrenocorticotrophic hormone (ACTH) secretion increases

When the median eminence of the hypothalamic is stimulated.

When aldosterone blood level falls.

When cortisol blood levels fall.

In bursts during the night as the normal hour of wakening approaches.

Following severe trauma.

448. Melatonin

Is produced mainly in the intermediate lobe of the pituitary gland.

Is synthesized in the body from serotonin (5-hydroxytryptamine).

Affects the level of pigmentation in human skin.

Blood levels are highest during the night.

Influences the secretion rates of pituitary hormones.

449. Thyroid hormones, when secreted in excess, may cause an increase in the

Peripheral resistance.

Frequency of defaecation.

Energy expenditure required for a given workload.

Duration of tendon reflexes.

Heart rate when cardiac adrenergic and cholinergic receptors are blocked.

450. Aldosterone secretion is increased by an increase in plasma

Volume.

Osmolality.

Potassium concentration.

Renin concentration.

ACTH concentration.

MCQ

194

Endocrine system – answers

Answers

445.

False

It is the time it takes for the initial concentration to fall by half.

False

It is much shorter (about ﬁve minutes); this allows more precise and continuous
regulation of the blood glucose level.

True

It is much longer since moment to moment regulation of its level is less critical.

True

It is more highly protein-bound which appears to prolong its life.

True

Acetylcholine is broken down almost immediately by cholinesterase.

446.

True

The waking catabolic state changes to an anabolic state.

True

Insulin secretion occurs mainly in association with meals.

True

Adrenaline secretion is associated with stress.

False

This rises as plasma osmolality rises; water is lost but not replaced during sleep.

False

This increases, allowing growth and anabolic repair of tissue wear and tear.

447.

True

The median eminence secretes corticotropin-releasing hormone (CRH), the releas-
ing hormone for ACTH.

False

Aldosterone secretion is regulated mainly by the renin/angiotensin system.

True

This negative feedback helps to maintain the blood cortisol level.

True

This is part of the circadian rhythm which produces high morning cortisol levels.

True

Most forms of stress increase ACTH output by their neural input to the median
eminence of the hypothalamus where CRH is formed.

448.

False

Melanocyte-stimulating hormone is produced in the intermediate lobe of the
pituitary; melatonin is produced mainly in the pineal gland.

True

The necessary enzymes are in the pineal parenchymal cells.

False

It has no role in regulation of human skin pigmentation.

True

Melatonin secretion has a pronounced circadian rhythm, low during the day and
high by night.

True

Melatonin secreted in relation to prevailing conditions of light/darkness may
adjust pituitary hormonal rhythms appropriately.

449.

False

Increased metabolism leads to peripheral vasodilation.

True

The frequency of defaecation increases in hyperthyroidism.

True

Thyroid hormones uncouple oxidation from phosphorylation so that more energy
appears as heat.

False

The reverse is true.

True

This suggests a direct action on cells in the sinoatrial node.

450.

False

This reduces aldosterone secretion.

False

This increases adrenocortical hormone (ADH) secretion.

True

⫹

has a direct stimulatory effect on the adrenal cortex.

True

This leads to formation of angiotensin II which stimulates the cortex.

True

Though the main action of ACTH is on glucocorticoid secreting cells; it has some
action on mineralocorticoid secreting cells.

MCQ

Endocrine system – questions

195

Questions 451–456

451. Glucocorticoid injections lead to increases in

Lymph gland size.

Fibroblastic activity.

Anabolic activity in muscle.

Bone resorption.

Membrane stability in mast cell and lysosomes.

452. An intravenous infusion of noradrenaline differs from one of adrenaline

in that it

Acts on alpha adrenoceptors.

Does not act on beta adrenoceptors.

Raises total peripheral resistance.

Increases cardiac output.

Decreases skin blood flow.

453. Growth hormone

Promotes positive nitrogen and phosphorus balance.

Secretion is under hypothalamic control.

Levels in the blood are higher in children than in adults.

Secretion surges during sleep.

Stimulates the liver to secrete somatomedins which regulate bone and cartilage growth.

454. Parathormone

Secretion is regulated by a pituitary feedback control system.

Acts directly on bone to increase bone resorption.

Decreases the urinary output of calcium.

Decreases phosphate excretion.

Promotes absorption of calcium from the intestines.

455. Antidiuretic hormone (vasopressin)

Is released from nerve endings in the posterior pituitary gland.

Tends to raise the osmolality of plasma rise.

Increases the permeability of the cells in the loop of Henle to water.

Secretion is little affected by changes in plasma osmolality of less than 10 per cent.

Secretion increases when plasma volume falls but osmolality is unchanged.

456. Pancreatic glucagon

Is produced by the beta cells of the islets of Langerhans.

Is a polypeptide.

Output is inversely proportional to the blood glucose level.

Has a half-life in the circulation of 3–4 hours.

Increases the breakdown of liver glycogen.

MCQ

196

Endocrine system – answers

Answers

451.

False

Glucocorticoids inhibit mitotic activity in lymphocytes.

False

Glucocorticoids inhibit ﬁbroblastic activity; this may allow chronic infections to
spread since they are not walled off effectively by ﬁbrous scarring.

False

They are catabolic; released amino acids are converted to glucose.

True

Decreased bone formation and increased resorption may cause osteoporosis.

True

This blocks release of histamine and lysosomal enzymes in allergic responses.

452.

False

Both act on alpha receptors but noradrenaline is the more potent stimulant.

False

Both act on beta receptors but adrenaline is the more potent stimulant.

True

Noradrenaline raises but adrenaline reduces it.

False

Adrenaline raises but noradrenaline reflexly reduces it.

False

Both constrict skin vessels due to their alpha receptor stimulant properties.

453.

True

It is an anabolic hormone.

True

Secretion in the pituitary is stimulated by growth hormone releasing factor and
inhibited by somatostatin from the hypothalamus.

False

Blood levels are similar in children and adults.

True

Sleep is a time for anabolic activity.

True

Somatomedins (insulin-like growth factors, IGF) from the liver inhibit the pitui-
tary secretion of growth hormone and stimulate release of somatostatin from the
hypothalamus.

454.

False

It is regulated directly by the calcium level in the blood that perfuses it.

True

It stimulates osteoclasts to resorb bone; excessive secretion causes cysts to form.

False

The high blood calcium levels with parathormone and the resulting increase in
calcium ﬁltration in the glomeruli result in an increased calcium output in urine.

False

It increases phosphate excretion by reducing renal phosphate reabsorption.

True

It does this indirectly by stimulating 1,25-dihydroxycholecalciferol production.

455.

True

It is formed in neurones whose cell bodies lie in the hypothalamus and whose
axons transport it to the posterior pituitary gland.

False

The water retention it induces makes plasma osmolality fall.

False

It increases the permeability of the collecting ducts.

False

Secretion is affected by 1 per cent changes in osmolality; the sensitivity of the
hypothalamic receptors to osmolar change accounts for the constancy of plasma
osmolality.

True

Volume changes detected by vascular low-pressure receptors affect ADH secre-
tion.

456.

False

It is produced by the alpha cells.

True

It is quite similar in structure to secretin.

True

It normally prevents a serious fall in blood glucose.

False

It is much shorter (5–10 minutes); this allows glucagon levels in the blood to
adjust rapidly to changes in blood glucose levels.

True

It also mobilizes fatty acids.

MCQ

Endocrine system – questions

197

Questions 457–462

457. The concentration of ionized calcium in plasma is

The main regulator of parathormone secretion.

Less than the free ionized calcium concentration in intracellular fluid.

About 50 per cent of the total plasma calcium concentration.

Reduced when plasma pH rises.

Reduced when the plasma protein level rises.

458. Cortisol

Is bound in the plasma to an alpha globulin.

Is inactivated in the liver and excreted in the bile.

Injections lead to a rise in arterial pressure.

Inhibits release of ACTH from the anterior pituitary gland.

Is released with a circadian variation so that cortisol blood levels peak in the morning.

459. When secretory activity in the thyroid gland increases

The gland takes up iodide from the blood at a faster rate.

Its follicles enlarge and ﬁll with colloid.

The follicular cells become more columnar.

The follicular cells ingest colloid by endocytosis.

The blood level of thyrotropin (TSH) increases.

460 Releasing hormones produced in the hypothalamus

Are secreted by cells in the median eminence.

Pass down nerve axons to reach the pituitary gland.

May control the output of more than one pituitary hormone.

Regulate the release of thyrotropin.

Regulate the release of oxytocin.

461. Adrenaline secretion from the adrenal glands increases the

Blood glucose level.

Blood free fatty acid level.

Blood flow to skeletal muscle.

Blood flow to the splanchnic area.

Release of renin in the kidneys

462. Thyroid-stimulating hormone (TSH) secretion is increased

After partial removal of the thyroid gland.

In infants born without a thyroid gland.

When metabolic rate falls.

In starvation.

When the diet is deﬁcient in iodine.

MCQ

198

Endocrine system – answers

Answers

457.

True

Parathormone secretion is stimulated by a fall in the ionized Ca

⫹

level.

False

It is more than 10

times higher.

True

Most of the rest is bound to protein, mainly albumin.

True

In alkalosis more calcium is protein-bound.

False

The ionized calcium level is regulated independently.

458.

True

It is bound to transcortin; free cortisol is released to replace that taken up by the
tissues.

False

The inactive products of cortisol degradation in the liver are conjugated with glu-
curonic acid and sulphate and excreted in the urine.

True

Partly at least because of its mineralocorticoid effects.

True

The negative feedback loop that maintains plasma cortisol levels constant.

True

It is regulated through a hypothalamic ‘clock’.

459.

True

Iodide uptake is an index of activity.

False

The follicles shrink as the colloid content falls.

True

They change from cuboidal to columnar as their activity increases.

True

Reabsorption lacunae form as thyroglobulin is broken down to release hormones.

False

Negative feedback causes TSH levels to fall.

460.

True

From there they travel to the anterior pituitary gland.

False

They are carried in the hypophyseal-portal vessels from median eminence to
anterior pituitary gland.

True

For example, Gonadotrophin-releasing hormone (GnRH) controls pituitary secre-
tion of follicle-stimulating hormone (FSH) and luteinizing hormone (LH).

True

Thyrotropin-releasing hormone (TRH) controls thyrotropin release.

False

Oxytocin is released from terminals of nerves running from the hypothalamus to
the posterior pituitary gland.

461.

True

By promoting glycogenolysis in the liver.

True

By promoting lipolysis in the fat stores.

True

By its predominant effect on beta-receptors in the smooth muscle of skeletal
muscle arterioles.

False

Splanchnic flow falls since alpha-receptors predominate in splanchnic arterioles.

True

Juxtaglomerular cells respond to beta-receptor stimulation by releasing renin.

462.

True

Due to a reduction in pituitary inhibition by circulating thyroxine.

True

Due to absence of the normal pituitary inhibition by circulating thyroxine.

False

TSH and thyroxine influence metabolic rate, not vice versa.

False

The level falls, which tends to conserve energy.

True

Due to inadequate manufacture of thyroxine, pituitary inhibition is reduced.

MCQ

Endocrine system – questions

199

Questions 463–468

463. Insulin

Stimulates release of free fatty acids from adipose tissue.

Secretion tends to raise the plasma potassium level.

Facilitates entry of glucose into skeletal muscle.

Facilitates entry of amino acids into skeletal muscle.

Secretion is increased by vagal nerve activity.

464. The pituitary gland

Regulates activity in all other endocrine glands.

Output of prolactin is regulated by hypothalamic releasing factors.

Secretes antidiuretic hormone when blood osmolality falls.

Has an intermediate lobe which secretes melanotropin

Responds to nervous and hormonal influences from the brain.

465. Thyrocalcitonin

Is produced by the follicular cells of the thyroid gland.

Increases basal metabolic rate.

Reduces blood calcium in parathyroidectomized animals.

Secretion occurs when the blood phosphate level rises.

Stimulates osteoclast activity.

466. The thyroid gland

Takes up iodide against its electrochemical gradient.

Decreases in size when dietary iodine is deﬁcient.

Is relatively avascular.

Contains enzymes which oxidize iodide to iodine.

Contains enzymes which iodinate tyrosine.

467. Adrenaline differs from noradrenaline in that it

Increases the heart rate when injected intravenously.

Is the main catecholamine secreted by the adrenal medulla.

Increases the strength of myocardial contraction.

Is a more potent dilator of the bronchi.

Constricts blood vessels in mucous membranes.

468. Growth hormone secretion

Is stimulated by somatostatin released from the hypothalamus.

Increases when the blood glucose level falls.

Has a lactogenic effect.

Increases the size of viscera.

Stimulates liver production of somatomedins.

MCQ

200

Endocrine system – answers

Answers

463.

False

It stimulates uptake of fatty acids by adipose tissue.

False

It lowers it by promoting potassium uptake by cells.

True

Thus lowering the blood sugar level.

True

Thereby favouring anabolism.

True

This mobilizes insulin at the beginning of a meal.

464.

False

For example, parathyroid activity is not regulated by the pituitary.

True

Output can be increased and decreased by the action of prolactin-releasing hor-
mone (PRH) or prolactin-inhibiting hormone (PIH) respectively.

False

ADH is secreted by the posterior pituitary in response to a rise in blood osmolal-
ity.

True

This may stimulate melanin production in human melanocytes.

True

The anterior pituitary is influenced by hormones arriving in portal-hypophyseal
vessels and the posterior pituitary by impulses travelling in the hypothalamo-
hypophyseal tract.

465.

False

It is produced by ‘parafollicular’ cells in the thyroid thought to be derived from
the ultimobranchial bodies.

False

It does not affect basal metabolic rate.

True

Its action is independent of the parathyroid glands.

False

It is secreted when the blood calcium level rises.

False

It stimulates bone deposition by osteoblasts.

466.

True

It is taken up by an active process (the iodide pump).

False

Hyperplasia due to TSH stimulation occurs to give goitre.

False

It has one of the highest blood flow rates in the body; bleeding during surgery
may be a problem.

True

This is a stage in the formation of thyroxine.

True

Iodination takes place in the colloid.

467.

True

Noradrenaline injection causes reflex slowing of the heart.

True

Adrenaline constitutes some 80 per cent of this secretion.

False

Both increase the strength of myocardial contraction.

True

It has stronger beta effects (including bronchodilation).

False

Both vasoconstrict (‘decongest’) mucous membranes.

468.

False

Somatostatin inhibits growth hormone secretion.

True

This is the basis of a test of pituitary function.

True

Prolactin and growth hormone are similar peptides.

True

It stimulates growth of most tissues.

True

These peptides mediate general stimulation of growth.

MCQ

Endocrine system – questions

201

Questions 469–475

469. Vitamin D

Increases the intestinal absorption of calcium.

Is essential for normal calciﬁcation of bones in childhood.

Requires hepatic modiﬁcation for activation.

Cannot be synthesized in the body.

Deﬁciency may result in hyperparathyroidism.

470. Prolactin

Has a similar chemical structure and physiological action to luteinizing hormone.

Is responsible for breast growth in puberty.

Release is inhibited by dopamine.

Secretion is stimulated by suckling of the breast.

Causes pre-formed milk to be ejected by the breast during suckling.

471. The level of ionized calcium in blood falls when

Blood phosphate levels fall.

Subjects hyperventilate.

The thyroid gland is perfused with a calcium-rich solution.

Plasma protein levels fall.

Sodium citrate is added to the blood.

472. Thyroxine

Is stored in the follicular cells as thyroglobulin.

Increases the resting rate of carbon dioxide production.

Is essential for normal development of the brain.

Is essential for normal red cell production.

Acts more rapidly than triiodothyronine (T

473. Parathormone

Decreases the renal clearance of phosphate.

Mobilizes bone calcium independently of its actions on the kidney.

Depresses the activity of the anterior pituitary gland.

In the blood rises when the calcium level falls.

Stimulates the ﬁnal activation of vitamin D (cholecalciferol) in the kidney.

474. The chemical structure of insulin

Contains a sterol ring.

Is identical in all mammalian species.

Is such that it is effective when taken by mouth.

Has been synthesized in the laboratory.

Can be synthesized by bacteria.

475. Hormones secreted by the adrenal cortex

Include cholesterol.

Are mostly bound to plasma proteins.

Include sex hormones.

Are excreted mainly in the bile after conjugation.

Are essential for the maintenance of life.

MCQ

202

Endocrine system – answers

Answers

469.

True

This occurs mainly in the upper small intestine.

True

In its absence bones are weak and deformed (rickets).

True

Initial (25-) hydroxylation occurs here.

False

It can be produced in mammals by the action of ultraviolet light on
7-dehydrocholesterol in skin.

True

The low blood calcium level stimulates parathormone secretion.

470.

False

They are distinct hormones with different actions.

False

Breast growth depends on oestrogens and progestogens.

True

This mediates hypothalamic regulation of prolactin levels.

True

This is responsible for the maintenance of lactation in the puerperium.

False

Milk ejection is a consequence of oxytocin secretion.

471.

False

It rises since the product of [Ca

⫹

] [PO

⫺

] is constant.

True

Alkalosis increases calcium binding by plasma proteins.

True

Due to release of thyrocalcitonin.

False

But the total calcium level falls.

True

This binds calcium ions and prevents clotting.

472.

False

It is stored as thyroglobulin in the follicles.

True

By increasing the basal metabolic rate.

True

Deﬁciency in infancy causes mental retardation (cretinism).

True

Thyroxine deﬁciency can cause anaemia.

False

acts within a day, thyroxine within 2–3 days.

473.

False

It increases it by depressing phosphate reabsorption.

True

It does so in the absence of the kidneys.

False

It does not affect the anterior pituitary.

True

Blood calcium level determines its rate of secretion.

True

From 25-hydroxy to 1,25-dihydroxycholecalciferol.

474.

False

It contains two peptide chains.

False

Minor differences occur but these differences do not affect insulin action.

False

Its peptide structure is broken down by digestive proteases in the gut.

True

In 1964 by Katsoyannis.

True

Using recombinant DNA.

475.

False

This is not a hormone.

True

For example, the globulin transcortin binds cortisol.

True

In both sexes they stimulate the growth of axillary and pubic hair.

False

After conjugation they are excreted mainly by the kidney.

True

Without replacement therapy, loss of adrenal cortical function results in death.

MCQ

Endocrine system – questions

203

Questions 476–482

476. During an oral glucose tolerance test the

Subject is given 5–10 grams of glucose.

Plasma glucose should rise by less than 10 per cent from the fasting level.

Plasma insulin should rise by about 100 per cent from the fasting level.

Rise in plasma glucose is less than with intravenous administration.

Rise in plasma insulin is less than with intravenous administration.

477. Secretin differs from cholecystokinin-pancreozymin (CCK-PZ) in that it

Is formed by mucosal cells in the upper small intestine.

Stimulates the pancreas to secrete a juice which is rich in digestive enzymes.

Stimulates the pancreas to secrete a watery alkaline juice.

Has less effect on gallbladder smooth muscle.

Decreases gastric motility.

478. Inhibition of angiotensin-converting enzyme (ACE) decreases the

Formation of angiotensin II.

Plasma renin level.

Work of the heart.

Circulating level of angiotensin I.

Total body potassium.

479. The plasma level of adrenocorticotrophic hormone (ACTH)

Is normally maximal around midnight.

Is regulated mainly by the blood cortisol level.

Shows exaggerated circadian fluctuations with an adrenal tumour.

Is raised in the presence of complete adrenal failure.

Is reduced in patients on long-term high dosage glucocorticoids.

480. Possible consequences of hypothyroidism include having

A subnormal body core temperature.

A tendency to fall asleep frequently.

Increased body hair (hirsutism).

Moist hands and feet.

Prominent eyeballs.

481. Sudden complete loss of parathyroid function

Leads to skeletal muscle spasms.

May be fatal if treatment is not given to raise the blood level of ionized calcium.

Causes haemorrhagic disease due to lack of calcium for haemostasis.

May be treated in the short-term by slow intravenous injection of calcium ions.

May be treated in the long-term by regular doses of vitamin D.

482. When a patient with diabetes insipidus is treated successfully with anti-

diuretic hormone the

Urinary flow rate should fall by about 50 per cent.

Urinary output should be reduced to around 5 ml/minute

Urinary osmolality should rise to between 100 and 200 mosmol/litre.

Salt intake should be carefully regulated.

Blood pressure should stabilize within the normal range.

MCQ

204

Endocrine system – answers

Answers

476.

False

50–100 grams of glucose are used.

False

It normally rises by around 50 per cent.

False

It rises about ten-fold from a very low fasting level.

True

The rise is about half as great.

False

Oral glucose stimulates much more release of insulin.

477.

False

Both are formed by these cells.

False

Secretin juice is poor in enzymes.

True

Secretin juice is copious and rich in bicarbonate ions.

True

‘Cholecystokinin’ implies stimulation of the gallbladder.

True

CCK-PZ resembles gastrin and increases gastric motility.

478.

True

The enzyme converts angiotensin I into angiotensin II.

False

Plasma renin rises as the blood pressure falls.

True

The fall in blood pressure it causes decreases the work of the heart and can be an
effective treatment for some types of heart failure.

False

It rises due to the increased renin and the inability to convert to angiotensin II.

False

Due to the fall in aldosterone secretion, less potassium is excreted.

479.

False

It is maximal around the time of awakening.

False

This feedback system is over-ridden by the hypothalamic circadian rhythm.

False

The level is high but the circadian rhythm is lost.

True

Due to loss of negative feedback by cortisol.

True

ACTH is suppressed by these exogenous glucocorticoids.

480.

True

Due to the lowered metabolic rate.

True

Due to the slowing of mental processes.

False

Hair loss is characteristic of hypothyroidism.

False

Decreased sweating is found in hypothyroidism.

False

Prominent eyeballs are characteristic of the exophthalmos of hyperthyroidism.

481.

True

This is a central feature of tetany.

True

Due to severe convulsions.

False

Calcium levels do not fall below the levels needed for haemostasis.

True

This is the acute treatment of choice, e.g. calcium gluconate.

True

This acts by increasing intestinal calcium absorption.

482.

False

Typically it will be reduced by about 80 per cent.

False

It should fall to the normal value of about 1 ml/minute.

False

It should rise to about 600–900 mosmol/litre, 2–3 times normal plasma osmolal-
ity (300 mosmol/litre).

False

ADH does not interfere with salt regulation.

True

Due to greater stability of the body fluids.

MCQ

Endocrine system – questions

205

Questions 483–489

483. Severe uncontrolled diabetes mellitus leads to a raised

⫹

ion concentration in body fluids.

Plasma K

⫹

concentration.

Urinary speciﬁc gravity and osmolality.

Blood volume.

Arterial P

484. Hyperthyroidism is associated with a

Positive nitrogen balance.

Decreased urinary excretion of calcium.

Clinical picture consistent with excessive beta adrenoceptor stimulation.

Diminished heat tolerance.

Rise in the level of thyroxine-binding protein in plasma.

485. An adrenal medullary tumour (phaeochromocytoma) may cause an

increase in

Systolic blood pressure which may be transient or constant.

Tremor of the extended hand.

Basal metabolic rate.

Diastolic arterial pressure which does not respond to alpha adrenoceptor blocking drugs.

Urinary catecholamines.

486. Short stature is seen in adults who in childhood suffered from

Chronic malnutrition.

Castration.

Premature puberty.

Thyroid deﬁciency.

Adrenal deﬁciency.

487. Insulin

Requirements at night are similar to those during the day.

Half-life is usually reduced in patients with diabetes mellitus.

Is partly bound to proteins in the blood.

Requirements are increased in obesity.

Requirements are increased by exercise.

488. The risk of tetany is increased by

Sudden rises in plasma bicarbonate.

Sudden rises in plasma magnesium.

Removal of the anterior pituitary gland.

The onset of respiratory failure.

The onset of renal failure.

489. Destruction of the anterior pituitary gland causes

Amenorrhoea.

Diabetes insipidus.

Skin pallor.

Impaired ability to survive severe stress.

A fall in basal metabolic rate (BMR).

MCQ

206

Endocrine system – answers

Answers

483.

True

This is a prime feature of ketoacidosis.

True

The excess H

⫹

ions compete with K

⫹

ions for excretion in the distal tubules.

True

Due to the dissolved glucose.

False

This falls due to osmotic diuresis and vomiting.

False

Hyperventilation reduces P

to compensate the metabolic acidosis.

484.

False

It is negative due to muscle wasting.

False

It rises due to liberation of calcium from bone.

True

Beta adrenoceptor blocking drugs relieve such features, e.g. tachycardia.

True

Heat intolerance is due to the increased heat production.

False

The protein levels are normal but they bind more thyroxine.

485.

True

Due to phasic or tonic release of adrenaline and/or noradrenaline.

True

Due to beta adrenoceptor stimulation by adrenaline.

True

Due to release of adrenaline.

False

␣-receptor blockers typically lower the blood pressure.

True

This is a diagnostic feature.

486.

True

Early stunting cannot be compensated for later in childhood.

False

This leads to increased height due to delayed closure of the epiphyses.

True

The sex hormones promote early closure of the epiphyses.

True

Thyroid hormones are essential for normal growth.

True

Adrenal hormones also are essential for normal growth.

487.

False

Insulin is required mainly in response to meals.

False

The disease is not usually due to rapid insulin breakdown.

True

Abnormal binding may occur in diabetes mellitus.

True

Obese patients usually show increased insulin resistance.

False

Exercise reduces insulin requirements.

488.

True

In alkalosis, the calcium-binding power of the plasma proteins increases.

False

Like calcium, magnesium ions tend to prevent tetany.

False

The pituitary is not involved in calcium homeostasis.

False

The acidosis in respiratory failure reduces calcium binding by protein.

False

The acidosis in renal failure also reduces calcium binding by protein.

489.

True

Due to absence of FSH and LH.

False

ADH is released from the posterior pituitary.

True

Due to loss of ACTH and melanocyte-stimulating hormone (MSH) actions.

True

Due to loss of ACTH and failure of the cortisol surge in response to stress; loss of
TSH and consequent hypothyroidism also contribute.

True

BMR falls due to loss of TSH drive to the thyroid.

MCQ

Endocrine system – questions

207

Questions 490–496

490. Removal of the thyroid gland (without replacement therapy) leads to an

increased

Blood TSH level.

Blood cholesterol level.

Blood glucose level during an oral glucose tolerance test.

Response time for tendon reflexes.

Tremor of the ﬁngers.

491. In severe diabetes mellitus, there may be a fall in

Extracellular fluid osmolality.

Appetite.

Blood volume.

Arterial blood pH to below 7.0.

Blood bicarbonate to half its normal value.

492. Excessive glucocorticoid production (Cushing’s syndrome) causes an

increase in

Skin thickness.

Bone strength.

Blood glucose.

Arterial pressure.

The rate of wound healing.

493. A pituitary tumour secreting excess growth hormone (GH) in an adult

may lead to

A homonymous hemianopia.

Giantism.

Reduced levels of somatomedins in blood.

Enlargement of the liver.

A raised blood glucose level.

494. Hypoglycaemic coma differs from hyperglycaemic coma in that there is

more likelihood of a

Rapid loss of consciousness.

Weak pulse.

Normal blood pH.

Glucose-free urine.

High acetone level in urine.

495. In adrenal failure there is likely to be a fall in the

Extracellular fluid volume.

Total red cell mass.

The sodium:potassium ratio in plasma.

Arterial blood pressure.

Blood urea.

496. In diabetic ketosis there is a decreased metabolic breakdown of

Ketones.

Glycogen.

Glucose.

Fat.

Amino acids.

MCQ

208

Endocrine system – answers

Answers

490.

True

Due to loss of negative feedback to the pituitary.

True

Due mainly to a reduction in cholesterol excretion.

False

The curve is flattened due to slow absorption of glucose.

True

The ‘hung up’ ankle jerk is a good example.

False

Tremor is a feature of hyperthyroidism.

491.

False

It rises due to excess glucose molecules plus water loss.

False

It is increased due to loss of glucose in the urine.

True

Due to osmotic diuresis and vomiting.

True

This indicates life-threatening acidosis.

True

Bicarbonate is used up buffering the keto-acids.

492.

False

Skin is thin due to protein catabolism; striae appear.

False

Bones are weakened by breakdown of the protein matrix.

True

Due mainly to gluconeogenesis.

True

Due to the salt and water retention caused by gluco- and mineralocorticoids.

False

Healing is slowed in this catabolic state.

493.

False

Damage to the crossing nasal retinal ﬁbres in the optic chiasma leads to bitem-
poral hemianopia.

False

After puberty when the epiphyses have closed, excess GH causes acromegaly.

False

GH leads to increased production of somatomedins in the liver.

True

Body organs as well as the peripheries increase in size in acromegaly.

True

Growth hormone has ‘diabetogenic’ effects.

494.

True

Blood glucose can drop more rapidly than diabetic ketosis can develop.

False

The pulse is usually strong in hypoglycaemic coma but weak in hyperglycaemic
coma because of fluid depletion.

True

Hypoglycaemia does not affect the pH.

True

However, glucose may be present if urine containing glucose entered the bladder
before the onset of hypoglycaemia.

False

Usually acetone is absent in hypoglycaemic coma.

495.

True

Due to salt and water loss from lack of gluco- and mineralocorticoids.

False

The haemoglobin level rises due to haemoconcentration.

True

It falls since loss of aldosterone leads to potassium retention.

True

Low blood volume may lead to hypotension and hypovolaemic circulatory fail-
ure.

False

It tends to rise due to the oliguria associated with the hypotension.

496.

False

Breakdown continues normally but ketones accumulate due to rapid production.

False

Insulin normally inhibits glycogenolysis.

True

Due to its impaired entry into the cells.

False

Fat breakdown is increased to yield ketone bodies.

False

Gluconeogenesis and amino acid catabolism increase.

MCQ

Endocrine system – questions

209

Questions 497–501

497. A patient with severe diabetic ketoacidosis is likely to benefit from

administration of

Intragastric fluids.

Intravenous insulin.

Isotonic glucose.

Isotonic sodium chloride.

Oxygen by breathing mask if hyperventilation is present.

498. Impaired growth hormone secretion

In children causes delayed puberty.

In children leads to short stature with more stunting of the limbs than the trunk.

Is associated with pale, ﬁne and soft skin.

In adults leads to a reduction in the size of the viscera.

Can be treated effectively with bovine growth hormone.

499. Parathormone secretion is usually increased

In patients with chronic renal failure.

In people taking excessive amounts of vitamin D.

In patients with anterior pituitary tumours secreting excessive amounts of its hormones.

When blood phosphate levels fall.

When plasma protein levels fall.

500. An oral glucose tolerance test in a patient with

Diabetes mellitus shows a higher than normal fasting blood glucose level.

Diabetes mellitus shows glycosuria when blood glucose is three times the normal fasting
level.

Diabetes mellitus shows a delayed return to the fasting blood glucose level.

An insulin-secreting tumour shows no rise in blood glucose level during the test.

Malabsorption syndrome shows a lower than normal peak level for blood glucose.

501. Surgical removal of the pituitary gland is likely to lead to a decrease in

Plasma osmolality.

Menstrual frequency.

Axillary hair.

Sexual desire (libido).

Breast size.

MCQ

210

Endocrine system – answers

Answers

497.

False

Vomiting is likely so intravenous fluids are needed to correct the fluid deﬁcit.

True

Insulin is needed to reverse the derangement of metabolism.

True

A water deﬁcit is remedied by intravenous isotonic glucose.

True

This remedies the extracellular fluid deﬁcit; the pH disturbance is corrected by
restoring normal metabolism and fluid balance.

False

The hyperventilation is due to acidosis, not oxygen lack.

498.

False

Pituitary gonadotrophins, not growth hormone, determine the time of onset of
puberty.

False

Pituitary dwarfs are usually normally proportioned.

True

In addition, body hair is normally sparse.

False

It has no detectable effect on organ size in adults.

False

Only the human form is effective.

499.

True

Phosphate retention results in a fall in the ionized calcium level in blood; this
stimulates the parathyroid to produce more parathormone (secondary hyper-
parathyroidism).

False

The increased level of ionized calcium in blood depresses parathyroid activity.

False

Pituitary hormones are not involved in the regulation of parathyroid activity.

False

This raises ionized calcium levels and depresses parathyroid activity.

False

This decreases the total blood calcium but not the ionized calcium level that reg-
ulates parathormone secretion.

500.

True

The level is higher due to impaired glucose homeostasis even in the fasting state.

True

The renal threshold for glucose is about twice the normal fasting level.

True

Due to impaired insulin response to the glucose stimulus.

False

Blood glucose rises but then falls to a low level due to excessive insulin secre-
tion.

True

The curve is flattened due to impaired glucose absorption.

501.

False

Osmolality increases due to the induced diabetes insipidus.

True

Amenorrhoea is common due to loss of gonadotrophic hormones.

True

The adrenal androgens responsible for axillary hair are under ACTH control.

True

Libido is influenced by the sex hormones which are under gonadotrophic control.

True

The oestrogen and progesterone responsible for breast development are under
gonadotrophic control.

MCQ

ENDOCRINE SYSTEM

211

EMQs

Questions 502–512

EMQ Question 502

For each action or function related to calcium and phosphate metabolism A–E, select the most
appropriate option from the following list.

1. Increased blood calcium.

2. Decreased blood calcium.

3. Increased urinary phosphate

4. Decreased urinary phosphate excretion.

excretion.

5. Increased alimentary absorption of calcium.

6. Decreased alimentary absorption of

7. Hydroxylation of cholecalciferol.

calcium.

An action of parathormone which increases the likelihood of renal calculi by its effect
on renal tubular function.

A hepatic function which is necessary for normal absorption of calcium from the gut.

An outcome of the action of parathormone on osteoclasts.

A renal function which is necessary for the absorption of calcium from the gut.

A consequence of vitamin D deﬁciency in childhood which can lead to softening and
deformity of bones (rickets) due to inadequate mineral content.

EMQ Question 503

For each hormone A–E, select the best option from the following list of functions.

1. Causes milk ejection in the lactating

2. Polypeptide growth factors secreted by the

breast.

liver.

3. Stimulates sperm formation in the

4. Stimulates melanin formation in

male.

melanocytes.

5. Promotes water retention in the kidney.

MSH.

Somatomedins.

Oxytocin.

Vasopressin.

Luteinizing hormone.

EMQ Question 504

For each of the paediatric problems A–E, select the best option from the following list of
causes.

1. Non-dysjunction of chromosome 21.

2. Adrenal cortical overactivity in children.

3. Pituitary deﬁciency.

4. Thyroid deﬁciency in children.

5. An XO chromosomal pattern.

Cretinism.

Precocious puberty.

Down’s syndrome.

Ovarian agenesis.

Dwarﬁsm.

EMQ

212

Endocrine system – answers

Answers for 502

Option 3

Increased urinary phosphate excretion. Parathormone liberates both calcium

and phosphate ions from bone and in order not to exceed the solubility product for these
ions it is necessary to excrete the excess phosphate. Parathormone favours this by inhib-
iting reabsorption of ﬁltered phosphate. It thereby tends to raise the solubility product for
these ions in urine, favouring development of renal calculi.

Option 7

Hydroxylation of cholecalciferol. Cholecalciferol is ingested or synthesized in

the skin under the influence of sunlight. To become an active hormone promoting absorp-
tion of calcium from the gut it must be converted into 1:25 dihydroxycholecalciferol. The
ﬁrst hydroxylation takes place in the liver.

Option 1

Increased blood calcium. Parathormone stimulates osteoclasts to erode bone,

thereby releasing calcium and phosphate. This raises the blood calcium level; the phos-
phate is excreted as discussed above.

Option 7

Hydroxylation of cholecalciferol. The second hydroxylation necessary for

activating vitamin D (cholecalciferol) takes place in the kidney under the influence of
parathormone. Both hydroxylations (liver and kidney) are necessary before vitamin D can
regulate total body calcium (mainly in bones) by stimulating its active absorption in the
upper small intestine.

Option 6

Decreased alimentary absorption of calcium. When vitamin D is deﬁcient

(dietary plus lack of adequate sunlight) the substrate for hydroxylation and activation is
not available and absorption of calcium is deﬁcient so that there is inadequate calcium
for normal bone mineralization.

Answers for 503

Option 4

Stimulates melanin formation in melanocytes. Melanocyte-stimulating hor-

mone results in a darker pigmentation of the skin.

Option 2

Polypeptide growth factors secreted by the liver. Their production is stimu-

lated by the action of growth hormone on hepatic cells. Somatomedins interact with
growth hormone and affect growth, cartilage and protein metabolism.

Option 1

Causes milk ejection in the lactating breast. It is also important in causing

the uterus to contract at parturition.

Option 5

Promotes water retention in the kidney. Also known as antidiuretic hormone,

vasopressin affects the permeability of certain parts of the renal tubule to allow greater
reabsorption of water ﬁltered in the glomerulus.

Option 3

Stimulates sperm formation in the male. In the female, LH stimulates ovu-

lation and luteinization of the corpus luteum.

Answers for 504

Option 4

Thyroid deﬁciency in children. Such children are dwarfed, mentally retarded

and pot bellied. Early treatment is urgent to prevent permanent mental retardation.

Option 2

Adrenal cortical overactivity in children. The adrenal cortex can manufac-

ture the sex hormones needed to initiate and maintain the secondary sexual characteris-
tics of puberty. Disordered hypothalamic or pituitary function can also cause precocious
puberty.

Option 1

Non-dysjunction of chromosome 21. The non-disjunction of chromosome 21

during meiosis usually occurs in the ovary and increases in frequency with the age of the
mother. Both of the chromosomes go to one of the daughter cells during meiosis.

Option 5

An XO chromosomal pattern. In this condition (Turner’s syndrome), the

zygote does not receive a sex chromosome from one of the parents. The gonads are rudi-
mentary or absent and the child develops female external genitalia. There is small stature
and sexual maturation does not occur at puberty.

Option 3

Pituitary deﬁciency. There are several causes of dwarﬁsm but one of the

causes is a hypothalamic or pituitary disorder that diminishes the secretion of growth hor-
mone.

EMQ

Endocrine system – questions

213

EMQ Question 505

For each substance A–E, select the best option for its functional description from the follow-
ing list.

1. A ‘mineralocorticoid’.

2. An androgen.

3. An alpha globulin that binds with

4. A ‘glucocorticoid’.

cortisol.

5. Causes breast development.

Corticosterone.

Progesterone.

Aldosterone.

Transcortin.

Dihydroepiandrosterone.

EMQ Question 506

For each item related to thyroid gland activity A–E, select the best option for its functional
description from the following list.

1. The most active form of the thyroid

2. A disease caused by thyroxine deﬁciency in

hormones.

adults.

3. Protrusion of the eyeballs seen in

4. A pituitary gland hormone that stimulates

patients with thyroid overactivity.

the thyroid gland.

5. A glycoprotein stored in colloid in thyroid gland follicles.

Thyroglobulin.

Triiodothyronine (T

TSH.

Myxedema.

Exophthalmos.

EMQ Question 507

For each item related to bone metabolism A–E, select the best option for its functional descrip-
tion from the following list.

1. Results in decalciﬁcation of bone in

2. Results in bone formation.

adults.

3. Results in breakdown of bone matrix.

4. Results in impaired calciﬁcation of

5. Results in inhibition of bone resorption.

bone in children.

Rickets.

Osteoblast activity.

Osteomalacia.

Osteoporosis.

Calcitonin.

EMQ

214

Endocrine system – answers

Answers for 505

Option 4

A ‘glucocorticoid’. Glucocorticoids promote protein catabolism, glucogene-

sis and gluconeogenesis.

Option 5

Causes breast development. Progesterone can be manufactured from preg-

nenolone in the adrenal cortex.

Option 1

A ‘mineralocorticoid’. Aldosterone promotes fluid retention by facilitating

sodium retention by the renal tubules.

Option 3

An alpha globulin that binds with cortisol. Most circulating cortisol is bound

to transcortin and is inactive. Cortisol is freed and becomes physiologically active when
free cortisol levels fall.

Option 2

An androgen. This can cause ‘virilization’ in female patients with adrenocor-

tical tumours.

Answers for 506

Option 5

A glycoprotein stored in colloid in thyroid gland follicles. Thyroglobulin is

manufactured in the thyroid follicular cells and is secreted by exocytosis of granules into
the colloid for storage. The hormones remain bound to the colloid until they are secreted
into blood capillaries.

Option 1

The most active form of the thyroid hormones. T

, which contains four iodine

molecules, is less physiologically active than T

Option 4

A pituitary gland hormone that stimulates the thyroid gland. TSH secretion

from the anterior pituitary gland is controlled by the hypothalamic hormone, thyrotropin-
releasing hormone (TRF).

Option 2

A disease caused by thyroxine deﬁciency in adults. A disease characterized

by low basal metabolic rate, coarse hair and skin, poor cold tolerance and mental slow-
ness.

Option 3

Protrusion of the eyeballs seen in patients with thyroid overactivity. Due to

swelling of the external ocular muscles and other orbital tissues.

Answers for 507

Option 4

Results in impaired calciﬁcation of bone in children. Rickets is due to lack

of vitamin D in children. Poor calcium absorption in the gut results in bones with low
mineral content that are easily deformed.

Option 2

Results in bone formation. Osteoblasts are bone-forming cells that can lay

down collagen and other proteins for the bone matrix.

Option 1

Results in decalciﬁcation of bone in adults. Osteomalacia is due to lack of

Vitamin D in adults, usually childbearing women. It results in demineralization and de-
formation of the bones. When this affects pelvic bones, it may interfere with normal par-
turition.

Option 3

Results in breakdown of bone matrix. Osteoporosis is caused by loss of bony

matrix and the resulting bone weakness permits easy bone fracture to occur, especially in
the elderly.

Option 5

Results in inhibition of bone resorption. Calcitonin is a hormone secreted by

the parafollicular cells of the thyroid gland. It lowers the blood calcium level by inhibit-
ing bone resorption.

EMQ

Endocrine system – questions

215

EMQ Question 508

For each effect related to glucose metabolism A–E, select the best option for a possible cause
from the following list.

1. Hypoglycaemia.

2. Metabolic acidosis.

3. Insulin deﬁciency.

4. Insulin.

5. Somatostatin.

Inhibition of insulin secretion.

Increased potassium uptake by muscle.

Negative nitrogen balance.

Increased secretion of glucagon.

Increased ventilation (Kussmaul breathing).

EMQ Question 509

For each endocrine disorder A–E, select the best option from the following list of effects.

1. Periodic episodes of severe hypertension.
2. Thirst, polyuria, obesity and

3. Stones in the urinary tract.

tiredness.

4. Tachycardia, sweating and heat intolerance.

5. Enlargement of the hands and feet and protrusion of the lower jaw.

Hyperparathyroidism.

Thyrotoxicosis.

Type 2 diabetes mellitus.

Adrenal medullary overactivity.

Acromegaly.

EMQ Question 510

For each endocrine disorder A–E, select the best option from the following list of effects.

1. Hypertension.

2. Polycythaemia.

3. Increased water and salt excretion.

4. Amenorrhoea.

5. Increased skin pigmentation.

Increased secretion of erythropoietin.

Decreased anterior pituitary secretion.

Increased secretion of renin.

Increased secretion of atrial natriuretic peptide (ANP).

Decreased adrenal cortical activity.

EMQ

216

Endocrine system – answers

Answers for 508

Option 5

Somatostatin. This is one of the effects of somatostatin secreted by the D

cells of the islets of Langerhans.

Option 4

Insulin. Insulin increases both potassium and glucose uptake by muscle

cells. Injections of glucose and insulin are sometimes given to lower potassium levels in
blood when they are dangerously high.

Option 3

Insulin deﬁciency. This results from the increased breakdown of protein for

gluconeogenesis in insulin deﬁciency.

Option 1

Hypoglycaemia. Glucagon acts to raise blood glucose by glycogenolysis and

gluconeogenesis.

Option 2

Metabolic acidosis. The increase in ventilation with Kussmaul breathing

results from stimulation of the respiratory system by the hydrogen ions liberated from
keto-acids formed in severe diabetes.

Answers for 509

Option 3

Stones in the urinary tract. Excessive parathormone secretion in hyper-

parathyroidism mobilizes calcium from bone. This calcium is excreted by the kidneys.
Phosphate is also mobilized from the bones in hyperparathyroidism and excreted in the
urine. When the calcium phosphate solubility product is exceeded, precipitation of cal-
cium phosphate occurs and results in the formation of stones.

Option 4

Tachycardia, sweating and heat intolerance. The high metabolic rate in

hyperthyroidism results in increased heat production and this is associated with tachycar-
dia, sweating and heat intolerance.

Option 2

Thirst, polyuria, obesity and tiredness. The high blood glucose level in dia-

betes cause polyuria and consequential thirst. Obesity increases the tendency to develop
type 2 diabetes.

Option 1

Periodic episodes of severe hypertension. Tumours in the adrenal medulla

called phaeochromocytomas that release noradrenaline and adrenaline periodically can
cause this.

Option 5

Enlargement of the hands and feet and protrusion of the lower jaw. Excessive

growth hormone production in the adult after the epiphyses have closed results in thick-
ening and enlargement of bones rather than their lengthening.

Answers for 510

Option 2

Polycythaemia. Erythropoietin acts on bone marrow cells to increase the

production of erythrocytes.

Option 4

Amenorrhoea. This is due to loss of FSH and LH secretions that are respon-

sible for maintaining the menstrual cycle.

Option 1

Hypertension. Renin from the kidneys causes hypertension by converting

angiotensinogen to angiotensin I that is subsequently converted to angiotensin II that
results in salt and water retention by the kidneys and an increase in peripheral resistance.

Option 3

Increased water and salt excretion. ANP is produced by atrial cells when they

are stretched and causes increased loss of sodium and water by an action on the renal
tubules.

Option 5

Increased skin pigmentation. One of the features of Addison’s disease caused

by loss of adrenal function is a bronze pigmentation of the skin. ACTH which is secreted
in large amounts when adrenal cortical function is depressed, has some melanocyte-
stimulating hormone (MSH) effect and this accounts for the skin pigmentation in
Addison’s disease.

EMQ

Endocrine system – questions

217

EMQ Question 511

For each hormonal disturbance A–E, select the best option from the following list of effects.

1. Poor wound healing, thin skin and

2. Raised arterial pressure, slow heart rate and

muscle wasting.

raised peripheral resistance.

3. Glycogenolysis, gluconeogenesis

4. Increased glycogen synthesis, potassium

and lipolysis.

uptake, triglyceride deposition and

5. Excessive thirst and urinary output.

hypoglycaemia.

Excessive secretion of glucagon.

Insufﬁcient secretion of vasopressin.

Excessive secretion of glucocorticoids.

Excessive secretion of noradrenaline.

Excessive secretion of insulin.

EMQ Question 512

For each of the releasing or inhibiting hormones A–E, select the best option from the follow-
ing list of effects.

1. An effect on somatomedin levels in

2. An effect on adrenal cortical activity.

the blood.

3. An effect on lactation.

4. An effect on spermatogenesis.

5. An effect on thyroid-stimulating hormone

(TSH) secretion.

Corticotrophin-releasing hormone (CRH).

Growth hormone-releasing hormone (GRH).

Prolactin-inhibiting hormone (PIH).

Thyrotropin-releasing hormone (TRH).

Luteinizing hormone-releasing hormone (LHRH).

EMQ

218

Endocrine system – answers

Answers for 511

Option 3

Glycogenolysis, gluconeogenesis and lipolysis. These are some of the mech-

anisms by which glucagon raises the blood glucose level.

Option 5

Excessive thirst and urinary output. Lack of vasopressin (ADH) secretion

causes diabetes insipidus. In this condition there is reduced water reabsorption in the renal
tubules and a consequential loss of body fluid that leads to thirst.

Option 1

Poor wound healing, thin skin and muscle wasting. Glucocorticoids promote

gluconeogenesis by the breakdown of protein in skin and muscle to form glucose.

Option 2

Raised arterial pressure, slow heart rate and raised peripheral resistance.

Noradrenaline constricts arterioles to raise arterial pressure and a consequential reflex
slowing of the heart.

Option 4

Increased glycogen synthesis, potassium uptake, triglyceride deposition and

hypoglycaemia. These are some of the actions of insulin that lowers the blood sugar level.

Answers to 512

Option 2

An effect on adrenal cortical activity. CRH from the hypothalamus stimulates

the anterior pituitary gland to produce ACTH.

Option 1

An effect on somatomedin levels in the blood. GRH stimulates the anterior

pituitary gland to secrete GH (growth hormone), which in turn promotes somatomedin
synthesis in the liver.

Option 3

An effect on lactation. PIH is involved in prolactin secretion from the ante-

rior pituitary gland. Reduction of PIH secretion seems to be the main factor in controlling
prolactin secretion. Prolactin stimulates milk formation in the breasts.

Option 5

An effect on TSH secretion. TRH (thyrotropin-releasing hormone) stimulates

the anterior pituitary gland to secrete TSH (thyroid-stimulating hormone) that in turn
increases activity in the thyroid gland.

Option 4

An effect on spermatogenesis. LHRH (luteinizing hormone-releasing hor-

mone) stimulates the anterior pituitary gland to secrete LH (luteinizing hormone) that in
the male promotes spermatogenesis.

EMQ

REPRODUCTIVE SYSTEM

219

MCQs

Questions 513–519

513. In the normal menstrual cycle

Blood loss during menstruation averages around 100 ml.

The proliferative phase depends on oestrogen secretion.

Cervical mucus becomes more fluid around the time of ovulation.

Ovulation is followed by a surge in blood luteinizing hormone level.

Basal body temperature is higher after ovulation.

514. Fertilization of the human ovum normally

Occurs in the uterus.

Prevents further spermatozoa from entering the ovum.

Occurs 2–5 days after ovulation.

Occurs 5–7 days before implantation.

Leads to the secretion of human chorionic gonadotrophin (HCG) within two weeks.

515. Human spermatozoa

Contain 23 chromosomes.

Have enzymes in their heads which aid penetration of the ovum.

Are produced faster at 37 than at 32

Are motile in the seminiferous tubules.

Are stored mainly in the seminal vesicles.

516. After a baby is born, there is normally a fall in

Its systemic vascular resistance.

Its pulmonary vascular resistance.

Direct flow from pulmonary artery to aorta.

Direct flow from right to left atrium.

Direct flow from right to left ventricle.

517. Secretion of testosterone

Depresses pituitary secretion of LH.

Causes the epiphyses of long bones to unite.

May lead to a negative nitrogen balance.

Stimulates growth of scalp hair.

Stimulates growth of body hair.

518. Human chorionic gonadotrophic hormone (HCG)

Is a steroid.

Acts directly on the uterus to maintain the endometrium.

Is formed in the anterior pituitary

Blood level rises steadily throughout pregnancy.

Can be detected in the urine as an early sign of pregnancy.

519. Compared with the adult, the newborn has less ability to

Excrete bilirubin.

Maintain a constant body temperature.

Tolerate brain hypoxia.

Manufacture antibodies.

Resist infection.

MCQ

220

Reproductive system – answers

Answers

513.

False

It varies widely but averages about 30 ml (one ounce).

True

This occurs in the ﬁrst half of the cycle.

True

This mucus ‘cascade’ may facilitate sperm passage.

False

The LH surge precedes and initiates ovulation.

True

Metabolic rate is raised by progesterone.

514.

False

It occurs in the outer third of the uterine tube.

True

The zona pellucida becomes impermeable.

False

The ovum remains viable for only about a day.

True

During this time the fertilized ovum travels along the uterine tube and spends
several days free in the uterus.

True

This is necessary to maintain ovarian hormone production whose withdrawal
causes endometrial necrosis.

515.

True

Half the complement of human somatic cells.

True

These are in the acrosome (‘extremity body’).

False

Normal core temperature inhibits formation of spermatozoa.

False

At this stage they are non-motile and cannot fertilize.

False

They are stored in the epididymis.

516.

False

This rises due to closure of the umbilical arteries.

True

Due to expansion of the lungs and their blood vessels.

True

Flow in the ductus arteriosus reverses due to (A) and (B).

True

Again due to reversal of the pressure gradient.

False

Normally there is no opening in the intraventricular septum.

517.

True

This negative feedback keeps blood testosterone constant.

True

Sexual precocity can cause short stature.

False

Testosterone is anabolic and leads to skeletal muscle hypertrophy.

False

Scalp hair tends to recede.

True

This is a male secondary sexual characteristic.

518.

False

It is a glycoprotein resembling luteinizing hormone (LH).

False

It acts on the ovaries to maintain the corpus luteum.

False

It is formed in the chorion of the developing embryo.

False

It peaks in the ﬁrst three months of pregnancy and then declines.

True

An immunological technique is used to identify it.

519.

True

‘Physiological’ jaundice is due to immaturity of the liver.

True

Temperature-regulating mechanisms are also immature.

False

Fetal tissues are adapted to relative hypoxia.

True

Immunological competence develops around three months of age.

False

Maternal antibodies (supplied via the placenta and breast) provide effective pas-
sive immunity.

MCQ

Reproductive system – questions

221

Questions 520–526

520. Androgens are secreted in the

Testis by the seminiferous tubules.

Fetus in greater quantities than in early childhood.

In the female by the ovary.

In the male by the adrenal cortex.

In the male in decreasing quantities after the age of 30.

521. During pregnancy the

Uterine muscle enlarges due mainly to cell proliferation.

Uterus is quiescent until the onset of labour.

Breasts enlarge due mainly to the action of prolactin.

Haematocrit rises.

Basal metabolic rate rises by more than 10 per cent.

522. Males differ from females in that their

Pituitary glands secrete different gonadotrophic hormones.

Hypothalamus shows different patterns of hormone secretion.

Gonads produce gametes until later in life.

Blood gonadotrophin levels do not rise in later life.

Polymorphs show ‘drumsticks’ of chromatin on their nuclei.

523. Fetal haemoglobin

Is the only type identiﬁable in fetal blood.

Forms the bulk of total haemoglobin for the ﬁrst year of life.

Has a higher oxygen-carrying capacity than adult haemoglobin.

Binds 2,3-DPI more avidly than does adult haemoglobin.

Has a higher afﬁnity than the adult form for oxygen at low P

524. For normal development and fertility of spermatozoa there must be

Secretion of testosterone.

Secretion of luteinizing hormone.

Secretion of follicle-stimulating hormone.

A testicular temperature of 37

A sperm count of more than 10

/ml.

525. In the mammary glands

Milk formation is stimulated by oestrogen and progesterone.

Milk formation can be depressed by hypothalamic activity.

Maintenance of lactation depends on suckling.

Lactation ceases if the anterior pituitary gland is destroyed.

Milk ejection ceases if the posterior pituitary gland is destroyed.

526. The male postpubertal state differs from the prepubertal in that

The gonads are responsive to gonadotrophic hormones.

There is a greater output of l7-ketosteroids in the urine.

Skeletal muscle is stronger per unit mass of tissue.

The circulating level of follicle-stimulating hormone is higher.

Hypothalamic output of gonadotrophin-releasing factors is greater.

MCQ

222

Reproductive system – answers

Answers

520.

False

They are secreted by the interstitial cells of the testis.

True

Fetal androgens control male sex organ development.

True

The ovaries secrete small amounts of androgen.

True

Adrenal androgens control pubic and axillary hair growth in both males and
females.

True

There is a gradual fall, with no clear-cut ‘climacteric’.

521.

False

The enlargement is due more to an increase in the size of the muscle cells.

False

Spontaneous uterine contractions occur during pregnancy.

False

The enlargement is due mainly to oestrogen and progesterone.

False

It falls due to the increase in plasma volume.

True

It increases by about one-third.

522.

False

The gonadotrophic hormones are the same in males and females.

True

The female monthly cycle originates here.

True

Much later than the female menopausal age.

False

Both sexes show a rise in FSH and LH levels.

False

It is the female polymorphs that show this.

523.

False

The adult type appears around mid gestation.

False

It has almost disappeared by four months.

False

They have similar oxygen capacities.

False

It binds it less readily.

True

This aids oxygen transfer in the placenta.

524.

True

In its absence spermatogenesis is depressed.

True

This controls secretion of testosterone.

True

This also is required by the germinal epithelium.

False

Testicular temperature should be maintained around 32

False

The normal value is around 10

/ml.

525.

False

These depress milk formation during pregnancy; prolactin stimulates milk forma-
tion.

True

By release of prolactin-inhibiting hormone (dopamine).

True

This causes prolactin secretion which initiates and maintains lactation after deliv-
ery.

True

Milk formation ceases due to loss of prolactin.

True

Due to loss of oxytocin in response to suckling.

526.

False

They are responsive before puberty as well.

True

Due to greater production of sex hormones in the body.

True

This is one of the actions of testosterone.

True

This stimulates growth and function of the testes.

True

This initiates the various changes of puberty.

MCQ

Reproductive system – questions

223

Questions 527–532

527. In the placenta

Fetal and maternal blood mix freely in the sinusoids.

The P

in sinusoidal blood is similar to that in maternal arterial blood.

The barrier to oxygen diffusion is much greater than in alveoli.

Fetal blood in umbilical veins has a P

within 10 per cent of that in maternal sinusoids.

Fetal blood becomes more than 50 per cent saturated with oxygen.

528. During pregnancy, there is an increase in

Maternal blood volume to twice the normal level.

Peripheral resistance.

Venous tone.

Ligament laxity.

Maternal parathormone secretion.

529. In the fetal circulation the oxygen content of blood in the

Femoral artery is less than that in the brachial artery.

Superior vena cava is higher than that in the inferior vena cava.

Right ventricle is higher than that in the left ventricle.

Pulmonary artery is higher than that in the pulmonary veins.

Cerebral arteries is lower than in the maternal cerebral arteries.

530. Normal parturition depends on

An abrupt fall in placental secretion of oestrogen and progesterone.

Release of oxytocin from the posterior pituitary gland.

Activation of beta adrenoceptors in uterine muscle.

The presence of normal ovaries.

Innervation of the uterus.

531. The interstitial cells of the testis

Contribute to the volume of seminal fluid.

Are the source of the hormone inhibin.

Are stimulated to secrete by luteinizing hormone (LH).

Depend on hypothalamic activity to function properly.

Are non-functional unless the testis descends from the abdomen to the scrotum.

532. The size of the fetus at birth is likely to be smaller in

Small than in large mothers.

Multiple than in single fetus pregnancies.

Smoking than in non-smoking mothers.

Female than in male babies.

Firstborn than in subsequent babies.

MCQ

224

Reproductive system – answers

Answers

527.

False

The two circulations remain discrete.

False

It is about half the arterial level in this sluggish flow.

True

Due to a much thicker cellular barrier to diffusion.

False

It is about 50 per cent lower due to the thick diffusion barrier.

True

Due to its high afﬁnity for oxygen.

528.

False

It increases by about a third.

False

It decreases (large uterine vessels, vasodilation).

False

Venous tone decreases and varicose veins may develop in the legs.

True

Due to relaxin, which helps the birth canal to dilate.

True

Large amounts of calcium must be mobilized for the fetus.

529.

True

Due to deoxygenated pulmonary arterial blood passing through the ductus arte-
riosus to the descending aorta.

False

The IVC receives oxygenated blood from the placenta.

False

Deoxygenated SVC blood streams to the right ventricle while oxygenated IVC
blood streams via the foramen ovale to the left ventricle.

True

Since the lungs are not ventilated, oxygen is lost rather than gained in its pas-
sage through the fetal lungs.

True

Umbilical venous blood is only about 80 per cent saturated with oxygen and fetal
arterial oxygen levels cannot exceed this; fetal tissues are adapted to survive in
relative hypoxia.

530.

False

Secretion is maintained at high levels until parturition.

False

Birth can occur in the absence of the posterior pituitary.

False

Beta activation may be used to delay onset of labour.

False

Ovaries are not essential in late pregnancy and parturition.

False

Parturition can occur with a denervated uterus; the cause of the onset of normal
labour is unknown.

531.

False

They secrete testosterone into the circulation.

False

This hormone is produced by the seminiferous tubules.

True

LH is the interstitial cell-stimulating hormone in the male.

True

Gonadotropin releasing hormone from the hypothalamus is needed for LH secre-
tion.

False

Undescended testes can secrete testosterone.

532.

True

Fetal size has some relationship to uterine capacity.

True

Placental capacity per fetus is reduced.

True

Excessive alcohol intake during pregnancy also reduces fetal size at birth.

True

Males are on average about 200 grams heavier.

True

On average later children are 200 grams heavier.

MCQ

Reproductive system – questions

225

Questions 533–539

533. Testosterone secretion from the testis

Increases at puberty because LH levels increase.

Is responsible for the growth of facial hair.

Has a negative feedback effect on FSH secretion by the anterior pituitary gland.

Peaks in the early evening.

Is responsible for interest in the opposite sex.

534. The corpus luteum

Is essential for the secretory phase of the menstrual cycle.

Development is controlled by the pituitary gland.

Secretes hormones in early pregnancy when stimulated by pituitary gland hormones.

Is greyish-white in colour.

Begins to atrophy in the second month of pregnancy.

535. Erection of the penis

Cannot occur before puberty.

Is normally initiated by venoconstriction.

Depends on adrenergic sympathetic nervous activity.

Cannot occur after cervical spinal cord transection.

Is inhibited by ganglion-blocking drugs.

536. The placenta

Contains villi which transport glucose into fetal blood.

Can convert glucose into glycogen.

Can store iron and calcium.

Actively transports oxygen into fetal blood.

Allows certain proteins to pass from maternal to fetal blood.

537. The ovaries

Begin to develop ova at puberty when acted on by FSH.

Are required for cyclical menstrual activity.

Must have double follicular rupture if identical twins are conceived.

Cease to respond to FSH after the menopause.

Secrete hormones which constrict uterine vessels.

538. The normal seminal ejaculate

Has a volume of about 5–10 ml.

Comes mainly from the seminiferous tubules and epididymis.

Contains fructose from the seminal vesicles.

Contains phosphate and bicarbonate buffers.

Contains prostaglandins.

539. The 21st day of the menstrual cycle differs from the seventh in that the

Endometrium is thicker and contains glands.

Blood level of progesterone is higher.

Blood is oestrogen free.

Blood level of FSH is at a maximum.

Endometrial glycogen content is higher.

MCQ

226

Reproductive system – answers

Answers

533.

True

LH secretion is controlled by hypothalamic GnRH (LH/FSH RH).

True

Females given testosterone may develop a beard.

False

Inhibin secreted by the testis has a negative feedback effect on FSH secretion.

False

It peaks around the time of awakening.

True

Castrates have little interest in sex.

534.

True

By its secretion of oestrogen and progesterone.

True

It depends on luteinizing hormone (LH).

False

It is controlled by human chorionic gonadotrophin (HCG) from the early placenta.

False

It is yellow; corpus luteum is Latin for ‘yellow body’.

False

It is essential for the ﬁrst three months of pregnancy.

535.

False

It is not uncommon in infants.

False

It is normally initiated by arteriolar dilatation.

False

It depends on parasympathetic cholinergic nerves; activity in sympathetic nerves
is required for ejaculation.

False

It is based on a spinal reflex.

True

These block sympathetic and parasympathetic pathways.

536.

True

As in the intestinal villi.

True

This glycogen is stored in the placenta.

True

Also proteins and fat.

False

Oxygen transfer is accounted for by its pressure gradient.

True

For example, the gamma globulins concerned with passive immunity.

537.

False

The immature ova are formed before birth and no more are developed after birth.

True

Because of their secretion of oestrogen and progesterone.

False

Identical twins are derived from a single ovum.

True

Follicles disappear and are replaced by ﬁbrous tissue.

False

Withdrawal of ovarian hormones leads to vasoconstriction.

538.

False

The normal volume is 2–5 ml.

False

These contribute only about 20 per cent of volume.

True

Seminal vesicles contribute about 60 per cent of seminal volume (prostate 20 per
cent).

True

These help to neutralize acidic vaginal fluids.

True

Derived from seminal vesicles, prostaglandins may induce contractile activity in
the female genital tract.

539.

True

The endometrium is in the secretory phase of the cycle.

True

It is very low on the seventh day.

False

Oestrogen remains high in the second half of the cycle.

False

The maximum is around the 14th day.

True

Conditions are optimal for implantation.

MCQ

Reproductive system – questions

227

Questions 540–546

540. The newborn baby differs from the adult in that its

Urine has a lower maximum osmolality.

Urine has a lower minimum osmolality.

Blood–brain barrier is less permeable to bilirubin.

Temperature regulation is more efﬁcient because of brown fat.

Blood has a greater afﬁnity for oxygen at low oxygen pressures.

541. Changes in maternal physiology during pregnancy include a rise in

Nitrogen retention.

Mean arterial pressure of around 20 mmHg.

Arterial P

Tone in the urinary tract

The renal threshold for glucose.

542. Amniotic fluid is

Formed in early pregnancy by ﬁltration from fetal skin capillaries.

Formed in late pregnancy by ﬁltration from the gut mucosa.

Swallowed by the fetus.

Similar in electrolyte composition to plasma.

Inhaled and exhaled by the fetus.

543. Ejaculation of semen

Depends on a spinal cord reflex.

Depends on sympathetic nerve activity.

Involves rhythmic contractions of striated muscles.

Is accompanied by contraction of the cremasteric muscles.

Is followed by orgasm.

544. The fetus normally

Gains more weight in the last ten weeks of gestation than in the ﬁrst 30 weeks.

Has a higher haemoglobin level at term than a normal adult.

Stores sufﬁcient iron in the liver to last a year after birth.

Has a similar metabolic rate per metre

as an adult.

Passes rectal contents in the last three months of gestation.

545. Cessation of menstruation (secondary amenorrhoea) may occur because

Psychological stress.

Severe weight loss.

Continuous administration of oestrogens.

An adrenal tumour.

Continuous administration of gonadotropin-releasing hormone (GnRH).

546. Development of secondary sexual characteristics before age nine could be

Due to abnormal secretion of adrenal cortical hormones.

Associated with short stature.

Due to a hypothalamic tumour.

Due to a pituitary tumour.

Present in a normal health child.

MCQ

228

Reproductive system – answers

Answers

540.

True

Its ability to concentrate urine is poor.

False

Its ability to dilute urine is also poor.

False

It is more permeable and brain damage can result with high blood bilirubin levels.

False

Temperature regulation is poor in the newborn.

True

Because of persisting fetal haemoglobin.

541.

True

About 300 g nitrogen is retained, half by maternal tissues and half by fetal tis-
sues.

False

Blood pressure tends to fall, such a rise suggests disease.

False

It tends to fall due to increased ventilation.

False

Tone decreases and may lead to ureteric reflux and urinary infections.

False

It falls, and glucose may appear in urine at normal blood glucose levels.

542.

True

The non-keratinized skin is not waterproof.

False

It is formed by the kidneys and excreted as urine in late pregnancy.

True

Up to 0.5 litre/day is absorbed and excreted as urine.

True

The protein content is, however, much lower.

True

Surfactant from the lungs can be found in amniotic fluid in late pregnancy.

543.

True

The centre is in the lumbosacral region.

True

Stimulation of the hypogastric nerves in man can cause ejaculation.

True

These compress the urethra.

True

This causes elevation of the testicles.

False

Ejaculation and orgasm coincide.

544.

True

Fetal growth is exponential.

True

Around 170–200 grams/litre.

False

The stores last only a few months.

False

It is about twice as great due to rapid growth.

False

Passage of meconium before birth is a sign of distress.

545.

True

Psychological stress affects hypothalamic activity.

True

Amenorrhoea is common during starvation.

True

Continuous progesterone administration can have the same effect.

True

Androgens from the tumour may oppose the effects of female sex hormones on
the endometrium.

True

Normally GnRH secretion is pulsatile; thus interference with the normal hormone
rhythms can cause amenorrhoea and infertility.

546.

True

Adrenal androgens may lead to precocious puberty.

True

Sex hormones cause closure of the epiphyses.

True

If it secretes a gonadotropin-releasing hormone.

True

If gonadotropins are produced.

True

There is a wide scatter in the normal distribution of the age of onset of puberty.

MCQ

Reproductive system – questions

229

Questions 547–552

547. The fetal

Blood in umbilical veins contains more amino acid than maternal blood in uterine
veins.

Aorta has a higher rate of blood flow than the distal pulmonary artery.

Aortic blood pressure is lower than pulmonary arterial pressure.

Systemic resistance is higher than its pulmonary resistance.

Heart rate suggests fetal distress if it exceeds 100 beats/minute.

548. Lack of pulmonary surfactant

Is unlikely in infants born after 30 weeks gestation.

Can be diagnosed by examining the fetal amniotic fluid.

Increases the effort required for expiration.

Decreases the surface tension forces in the lungs.

Leads to poor oxygenation of the blood before birth.

549. A child whose sex chromosome pattern is

XY develops into a normal female.

XO shows incomplete sexual maturation at puberty.

XXX develops exaggerated female secondary sexual characteristics.

XXY develops into a true hermaphrodite.

XX is less likely to have haemophilia than one with XY.

550. The diagnosis of pregnancy is supported by finding

Conjugated progesterone in the urine.

Human chorionic gonadotrophin in the urine.

Viscous cervical mucus plugging the cervical canal.

Enlargement of the sebaceous glands in the mammary areolae.

A hardening of the cervical tissue.

551. The neonatal

Liver stores sufﬁcient vitamin K for the ﬁrst few months of life.

Blood volume is closer to 750 than 250 ml.

Blood glucose level fluctuates more than the fetal level.

Gut usually lacks certain enzymes needed for digestion of milk.

Peripheral vascular resistance is higher than that of the adult.

552. After a child is born

Its haemoglobin level rises steadily during the ﬁrst year.

There should be a delay in clamping the umbilical cord so that blood from the placenta
can drain into the fetus.

It should increase its weight by 10 per cent at four months.

Its brain can tolerate a lower blood glucose level than that of an adult.

Its brain can tolerate a lower oxygen level than that of an adult.

MCQ

230

Reproductive system – answers

Answers

547.

True

Amino acids are actively transported from maternal to fetal blood in the placenta.

True

Due to high flow through the ductus arteriosus to the aorta.

True

Blood flows from the pulmonary artery to the distal aorta.

False

Distal aortic flow is greater than distal pulmonary artery flow and the pressure is
lower (resistance

⫽pressure/flow).

False

It is normally about 140/minute; below 100 suggests distress.

548.

False

Its formation starts around the 35th week.

True

Fetal breathing movements wash it into this fluid.

False

It increases the work of inspiration.

False

Without surfactant the surface tension forces are great; these forces must be over-
come during inspiration.

False

The lungs are not used for gas exchange before birth; lack of surfactant causes
poor oxygenation in the neonate.

549.

False

He develops into a normal male.

True

The gonads fail to develop (Turner’s syndrome).

False

Abnormalities do not result.

False

He develops as a male with abnormal testes and a high risk of mental retardation
(Klinefelter’s syndrome).

True

Haemophilia is an X-linked recessive condition.

550.

False

This is normally present in the childbearing period.

True

This is not otherwise present.

True

Progesterone increases the viscosity of cervical mucus.

True

These are known as Montgomery’s tubercles.

False

The cervix softens during pregnancy.

551.

False

Vitamin K is not stored and deﬁciency at birth is common.

False

It would be about 240 ml in a three-kilogram neonate.

True

The neonatal liver is less mature than the maternal liver.

False

It can usually deal adequately with the nutrients in milk.

True

The AV pressure gradient is almost as great as in the adult and flow is much
smaller (resistance

⫽pressure gradient/flow).

552.

False

It falls from around 170–200 g/litre to around 110 g/litre.

True

The placenta contains about half as much blood as the fetus; some can be trans-
ferred by uterine contraction.

False

Its weight should be doubled at this stage and trebled at one year.

True

It can tolerate about 25 per cent of the normal adult fasting level.

True

Fetal tissues are adapted to survive moderate hypoxia.

MCQ

Reproductive system – questions

231

Questions 553–558

553. Removal of the testes in the adult causes

A rise in the pitch of the voice.

Loss of libido.

Loss of the ability to copulate.

Hot flushes, irritability and depression.

A fall in the blood levels of LH and FSH.

554. Administration of oestrogens and progestogens to women

Prevents menstruation if given daily throughout the year.

Tends to cause salt and water retention.

Depresses secretion of pituitary gonadotrophins.

Decreases the likelihood of ovulation.

Tends to accentuate acne vulgaris.

555. Secondary sexual characteristics do not develop in children

Who have been castrated.

Whose seminiferous tubules, but not interstitial cells, have been damaged by radiation.

Suffering from severe malnutrition.

With dwarﬁsm.

Lacking pituitary hormones.

556. Methods of reducing fertility include

Conﬁning intercourse to the period from the 10–20th day of the menstrual cycle.

Bilateral ligation and division of the uterine tubes.

Bilateral ligation and division of the vas deferens.

The use of agents which prevent the fertilized ovum from implanting.

Mechanical barriers (condoms and caps) which are the most effective methods.

557. Infertility usually occurs

When the sperm count is reduced to 10 per cent of normal.

When posterior pituitary function is lost.

When one uterine tube is blocked.

In males with undescended testes.

Because of a reproductive disorder in the female partner.

558. Maternal blood loss in the first 24 hours after delivery

Is considered abnormal if it exceeds 600 ml.

Is greater after a short than after a long labour.

Is increased if part of the placenta is retained.

May justify transfusion of unmatched AB Rh-positive blood.

May, if excessive, impair anterior pituitary function.

MCQ

232

Reproductive system – answers

Answers

553.

False

Laryngeal changes induced by testosterone are permanent.

True

Testosterone secretion increases libido.

False

The sexual reflexes persist in the absence of testosterone.

True

Rather like menopausal symptoms.

False

These rise due to loss of feedback inhibition.

554.

True

Withdrawal causes menstruation.

True

Possibly due to structural afﬁnity with mineralocorticoids.

True

By a negative feedback mechanism.

True

By suppressing pituitary gonadotrophins.

False

Oestrogens antagonize the effect of androgens on sebaceous glands and improve
acne.

555.

True

Gonadal hormones are essential for their development.

False

Testosterone promotes secondary sexual characteristics even if the germ cells
cannot develop.

False

They are delayed but appear eventually.

False

In most cases they develop.

True

These are required to stimulate the gonads to produce the essential sex hormones.

556.

False

This is the maximally fertile period.

True

This is difﬁcult to reverse.

True

An interval is necessary before infertility can be assumed.

True

Intrauterine devices (IUDs) act in this way.

False

Oral contraceptives and intrauterine devices are more effective.

557.

True

Even though only one sperm ultimately fuses with the ovum.

False

Vasopressin and oxytocin are not needed for fertilization.

False

This would only reduce fertility moderately.

True

The higher temperature in the abdomen impairs function in the spermatogenic
epithelium.

False

Male and female causes are about equally common in infertile couples.

558.

True

This is the threshold for post-partum haemorrhage.

False

After a long labour, the uterine contractions which normally close off the mater-
nal sinusoids may be less efﬁcient.

True

This also hinders sinusoidal compression.

False

Blood group O Rh-negative (universal donor) may be used.

True

This is a recognized complication (Sheehan’s disease).

MCQ

Reproductive system – questions

233

Questions 559–565

559. Failure to ovulate in a given cycle is likely if

Pregnanediol appears in the urine in the second half of the cycle.

Basal body temperature is constant throughout the cycle.

Unilateral abdominal pain is experienced at mid-cycle.

Cervical mucus showed evidence of unopposed oestrogen action in the second half of
the cycle.

The endometrium shows proliferating glands in the second half of the cycle.

560. Features indicating poor physical condition in the newborn include

A blue rather than a pale grey colour.

A steadily rising heart rate.

Spontaneous limb movements.

Relaxed muscles with low tone.

A grimace rather than a cough when the pharynx is stimulated.

561. Premature labour is associated with a greater

Risk of maternal complications.

Risk of cerebral haemorrhage in the fetus.

Fat content of the baby’s skin.

Fetal head to body size ratio.

Need to feed the baby with milk.

562. Following the menopause, the

Vaginal secretions become more acid.

Myometrium decreases in bulk.

Libido may increase.

Lack of sex hormones may produce general body changes.

Level of pituitary gonadotrophins falls markedly.

563. Women having their first child after the age of 35 have a greater

Average blood loss than younger women.

Incidence of ineffective uterine contractions during labour.

Compliance of the perineum and vagina.

Incidence of fetal abnormalities.

Risk of spontaneous abortion.

564. Infertility in the male can be explained by observations that

There are no motile sperms in semen 15 minutes after ejaculation.

50 per cent of the sperms in the semen are abnormal.

The sperm count is 10

/ml.

The sperm count is 50 per cent below average.

There is widespread autonomic neuropathy.

565. Pregnant women with five or more previous deliveries have a greater

risk of having

Anaemia.

An unfavourable presentation of the baby in the pelvis.

Complications due to rhesus incompatibility.

Serious loss of blood after delivery.

Involuntary urination while coughing (stress incontinence).

MCQ

234

Reproductive system – answers

Answers

559.

False

This is a normal derivative of progesterone which dominates the second half of
the cycle.

True

Normally there is a rise in the second half of the cycle.

False

This is a sign of ovulation (mittelschmerz).

True

Progesterone would normally prevent this effect (‘ferning’ due to salt crystals) in
the second half of the cycle.

False

Proliferating glands are normally present at this stage.

560.

False

The pale grey colour suggests circulatory failure.

False

This suggests recovery from vagal slowing.

False

These are a good sign.

True

This suggests severe hypoxia.

True

This indicates depressed reflexes.

561.

False

The fetus is smaller and is delivered more easily.

True

Due to the greater fragility of cerebral veins at this stage of maturity.

False

The skin tends to be brick red due to lack of fat.

True

The body ‘catches up’ in late pregnancy.

False

Milk is less well digested by premature infants.

562.

False

They become less acid; infection is more likely.

True

The uterus decreases in size.

True

It may increase or decrease.

True

Including osteoporosis and coronary artery disease.

False

It rises due to loss of sex hormone negative feedback.

563.

True

Uterine contraction is less effective in stopping bleeding.

True

Again, due to deteriorating uterine function with age.

False

It is less; Caesarean section is more often needed.

True

Down’s syndrome is one example of the genetic problems.

True

Fetal abnormalities may be an important cause of this.

564.

True

The sperms should be motile for at least one hour.

True

This indicates a serious defect in sperm formation.

False

This is the normal value.

False

The count must be below 10–20 per cent to cause infertility.

True

This neuropathy can affect the sexual reflexes.

565.

True

Due partly to depletion of iron stores.

True

Due to flabby uterine and abdominal wall muscles.

True

There have been more opportunities for sensitization.

True

Again due to deteriorating uterine function.

True

Due to pelvic damage.

MCQ

Reproductive system – questions

235

Questions 566–567

566. Secretion of androgens in the adult female

Is abnormal.

In large amounts can cause enlargement of the clitoris.

Does not affect the voice.

May lead to growth of facial hair.

May result in amenorrhoea.

567. Fetal death is likely to result from serious impairment of fetal

Liver function.

Alimentary tract function such as obstruction.

Renal function.

Cerebral function.

Cardiac function.

MCQ

236

Reproductive system – answers

Answers

566.

False

Adrenal androgen secretion is normal.

True

It may grow to resemble a small penis.

False

The voice deepens due to permanent laryngeal enlargement.

True

As in the male.

True

By suppressing the normal endometrial cycle.

567.

False

The maternal liver can compensate.

False

Fetal nutrition depends on the placenta.

False

The maternal kidneys can compensate.

False

Fetal survival does not depend on normal brain function.

True

Fetal circulation is needed to harness maternal support systems to supply fetal
needs.

MCQ

REPRODUCTIVE SYSTEM

237

EMQs

Questions 568–576

EMQ Question 568

For each aspect A–E, of multiple pregnancy (twins, triplets etc), select the most appropriate
option from the following list of obstetrical terms.

1. Individual fetal mass.

2. Total mass of all fetuses.

3. Fetal prematurity.

4. Neonatal mortality.

5. Placental adequacy.

6. Assisted reproduction.

7. Perinatal mortality.

A mother with multiple pregnancies is more likely to have an inappropriately early (pre-
mature) onset of labour.

Since there is always a risk of loss of the fetus in early pregnancy, starting with two or
more embryos increases the chance of at least one reaching maturity.

Multiple pregnancies decrease the likelihood of delayed labour due to inadequate size of
the birth canal.

Multiple births are associated with an increased risk of neonatal jaundice and, more
seriously, difﬁculty in overcoming surface tension forces during inspiration (respiratory
distress syndrome).

The chances of surviving problems in the weeks before and after birth are less for a
twin than a single birth, less still for a triplet and even less for a quadruplet.

EMQ Question 569

For each case of reduced fertility A–E, select the most appropriate option from the following
list of aspects of the male and female reproductive systems.

1. Ovulation.

2. Spermatogenesis.

3. Transport in the uterine tube.

4. Transport in the vas deferens.

5. Erection of the penis.

6. Ejaculation.

7. Implantation.

A couple’s infertility is attributed to medication with a drug which interferes with relax-
ation of vascular smooth muscle in the reproductive system.

Contraception is provided by a combination of oestrogen and progesterone given for 21
consecutive days in each month.

Contraception is provided by an intrauterine device.

A couple’s infertility is attributed to the man’s wearing a tight-ﬁtting garment which
holds the testes close to the trunk.

Infertility is attributed to surgery which has damaged sympathetic nerves in the pelvis.

EMQ

238

Reproductive system – answers

Answers for 568

Option 2

Total mass of all fetuses. Despite each fetus being small for its age, the total

mass is exceptionally large, exaggerating the likelihood of labour before completion of the
usual nine months of gestation.

Option 6

Assisted reproduction. Insertion of early embryos into the uterus as a means

of treating infertility is a common cause of multiple birth; such embryos are at increased
risk of abortion, so it is usual to insert several.

Option 1

Individual fetal mass. Each fetus of a multiple set is smaller than average at

the time of labour, so is less likely to be hindered by a relatively small birth canal.

Option 3

Fetal prematurity. The more premature the fetus, the less mature is its liver,

and the less able is it to conjugate the bilirubin load after birth; more seriously, it is also
much more likely not to have developed the capacity to produce adequate surfactant to
reduce the otherwise punishing effect of surface tension forces in the newborn lung.

Option 7

Perinatal mortality. This term refers to the risk of death in late pregnancy

and early infancy; it mounts dramatically with the number of fetuses because of the com-
bined effects of placental inadequacy, prematurity, and the problems of dealing with
multiple infants at one delivery.

Answers for 569

Option 5

Erection of the penis. Erection depends on relaxation of smooth muscle in

arterioles supplying the erectile tissue of the penis; its failure is described as impotence,
in which condition ejaculation is not possible.

Option 1

Ovulation. The contraceptive pill leads to feedback inhibition of release of

the gonadotrophins follicle-stimulating hormone and luteinizing hormone which control
maturation and release of the ovum.

Option 7

Implantation. The intrauterine device interferes with implantation of the fer-

tilized ovum.

Option 2

Spermatogenesis. This type of garment can raise the testicular temperature

to a level where spermatogenesis is considerably impaired, leading to reduced fertility.

Option 6

Ejaculation. Ejaculation depends on sympathetic nerves for expulsion of

seminal fluid into the urethra, and also for contraction of the bladder neck to prevent ret-
rograde ejaculation into the bladder.

EMQ

Reproductive system – questions

239

EMQ Question 570

For each aspect A–E of the male and female reproductive systems, select the most appropriate
option from the following list of hormones.

1. Follicle-stimulating hormone.

2. Gonadotrophin-releasing hormone.

3. Inhibin.

4. Luteinizing hormone.

5. Oestradiol.

6. Progesterone.

7. Testosterone.

A peptide hormone formed in testes and ovaries which acts as a local growth factor and
also gives negative feedback to the hypothalamic–pituitary axis.

A steroid hormone formed in the testes which is necessary for normal spermatogenesis.

A peptide hormone formed in the hypothalamus which is necessary for normal sper-
matogenesis.

A steroid hormone which accounts for the rise in metabolic rate in the second half of
the menstrual cycle.

A peptide hormone which plays a major role in both ovulation and the activity of the
interstitial (Leydig) cells in the testis.

EMQ Question 571

For each effect of pregnancy A–E, select the most appropriate option from the following list of
physiological terms.

1. Smooth muscle relaxation.

2. Smooth muscle constriction.

3. Brainstem reflex.

4. Sacral spinal cord reflex.

5. Decreased metabolic rate.

6. Increased metabolic rate.

The pregnant woman feels excessively hot in quite cool conditions; she dresses more
lightly than most people and is keen to have windows opened for ventilation.

The pregnant woman has suffered several episodes of urinary frequency with a burning
sensation on passing urine; this has been attributed to urinary infection, from which she
has not previously suffered.

The pregnant woman suffers frequently from a burning sensation referred to the mid
line of the chest; she didn’t have it before pregnancy, it is not related to taking exercise,
but indigestion tablets seem to help.

The woman in early pregnancy feels severely nauseated and quite frequently vomits,
particularly ﬁrst thing after getting up.

Despite eating more than usual, the pregnant woman suffers from decreased frequency
and difﬁculty in defaecation.

EMQ

240

Reproductive system – answers

Answers for 570

Option 3

Inhibin. This hormone (like many others) exists in several forms sometimes

referred to as the inhibins; in the testis it is formed by Sertoli cells which nurture sper-
matozoa, so are a marker for spermatogenesis, completing the feedback loop.

Option 7

Testosterone. Among its widespread effects, testosterone, which is formed by

interstitial cells of the testis, is responsible for spermatogenesis in the seminiferous
tubules.

Option 2

Gonadotrophin-releasing hormone. This key hormone is required for the

release of follicle-stimulating and luteinizing hormones in both sexes, so is responsible for
all sexual activity; control by the hypothalamus allows the complicated control which is
different in the two sexes, so that, while male sexual activity shows no regular fluctua-
tion, female sexual activity follows the monthly cycle, which can be modiﬁed by nutri-
tional and psychological factors.

Option 6

Progesterone. As implied by its name, this hormone is particularly associated

with gestation; in the second half of the cycle it stimulates development in the endo-
metrium which favours implantation of a fertilized ovum.

Option 4

Luteinizing hormone. A surge of this hormone is the precursor of ovulation

and it also acts in the testis, giving it the secondary name of interstitial cell-stimulating
hormone; note that, as in the body generally, hormones are either peptide or steroid based;
in the reproductive system the peptides tend to be common to male and female, whereas
the steroids make the difference.

Answers for 571

Option 6

Increased metabolic rate. These symptoms are like those of hyperthyroidism;

in both cases the resting metabolic rate is increased; this leads to a parallel increase in
heat production, so a cooler environment is needed for thermoneutrality.

Option 1

Smooth muscle relaxation. The hormones of pregnancy induce smooth

muscle relaxation in many parts of the body; loss of tone in the bladder hinders complete
emptying and favours reflux into the ureters; the urinary stasis favours infection.

Option 1

Smooth muscle relaxation. This time the muscle involved is the cardiac

sphincter; loss of tone favours reflux of acid from the stomach into the oesophagus where
the very low pH causes burning pain – ‘heartburn of pregnancy’.

Option 3

Brainstem reflex. ‘Morning sickness’ is a classical sign of early pregnancy;

the vomiting reflex is stimulated, possibly by the sudden change in hormonal levels, sharp
rise in chorionic gonadotrophin, and rises in oestrogen and progesterone.

Option 1

Smooth muscle relaxation. Again this is the problem, this time affecting the

lower bowel so that emptying of the rectum is inefﬁcient.

EMQ

Reproductive system – questions

241

EMQ Question 572

For each aspect of labour A–E, select the most appropriate option from the following list of
muscle activities.

1. Smooth muscle relaxation.

2. Smooth muscle contraction.

3. Skeletal muscle relaxation.

4. Skeletal muscle contraction.

The onset of the ﬁrst stage of labour is when regular spasms of abdominal pain begin
(labour pains).

The onset of the second stage of labour is when the uterine cervix becomes fully dilated.

During the second stage of labour the mother is encouraged to make powerful bearing
down/pushing actions to help deliver the baby.

After the third stage of labour which ends with the expulsion of the placenta, the
mother may be given oxytocin, or encouraged to put the infant to the breast.

During the ﬁrst stage of labour, the mother is encouraged to avoid bearing down actions
and breath-holding so that the baby is not forced against an incompletely dilated
cervix.

EMQ Question 573

For each description of a phase in the menstrual cycle A–E, select the most appropriate option
for the following list of days.

1. Day 0.

2. Day 4.

3. Day 7.

4. Day 14.

5. Day 21.

6. Day 27.

Vaginal secretions are at their most fluid; the endometrium has regenerated but is not
yet optimal for implantation.

The endometrium has undergone ischaemic necrosis (death due to lack of blood flow)
and external discharge has been noted.

The level of luteinizing hormone is around its peak, the level of oestradiol is medium,
and that of progesterone relatively low.

The menstrual discharge has just ended.

The level of progesterone is around its peak.

EMQ Question 574

For each aspect of spermatogenesis and the seminal ejaculate A–E, select the most appropriate
option from the following list of components of the male reproductive system.

1. Leydig cells.

2. Sertoli cells.

3. Seminiferous tubules.

4. Epididymis.

5. Seminal vesicles.

6. Prostate gland.

7. Vas deferens.

At their site of formation, the spermatozoa acquire the haploid number of chromosomes.

Testosterone, which is essential for normal spermatogenesis, is produced by cells stimu-
lated by follicle-stimulating hormone.

Spermatozoa are stored for some 2–4 weeks, while their motility and ability to fertilize
steadily increase.

Most of the volume of the seminal ejaculate consists of a slightly alkaline fluid rich in
fructose.

The spermatozoa in the seminal ejaculate leave the scrotum because of powerful
contraction of smooth muscle cells.

EMQ

242

Reproductive system – answers

Answers for 572

Option 2

Smooth muscle contraction. Labour begins when the state of uterine quies-

cence is replaced by regular, painful, contractions of the uterine smooth muscle.

Option 1

Smooth muscle relaxation. Full relaxation of the smooth muscle in the ute-

rine cervix sets the stage for passage of the baby; in the body generally, expulsion is
achieved by contraction behind and relaxation in front of what is being expelled; in the
heart expulsion of contents takes place on a very short time scale, in the bladder and
rectum it is longer, and in the uterus the time scale is relatively very long.

Option 4

Skeletal muscle contraction. This is a form of the Valsalva manoeuvre, where

abdominal skeletal muscle contracts to favour expiration against a closed glottis; this
manoeuvre helps expulsion of abdominal contents when the relevant oriﬁce is open as
well as in delivery of the baby, the maneouvre has a part is speeding micturition and def-
aecation, and in producing vomiting.

Option 2

Smooth muscle contraction. Oxytocin favours powerful contraction of the

uterine smooth muscle which helps to limit bleeding after delivery (post-partum haemor-
rhage); stimulation of the breast by the baby leads to release of endogenous oxytocin from
the posterior pituitary.

Option 3

Skeletal muscle relaxation. The mother cannot influence the uterine contrac-

tions, but can favour relaxation of the abdominal muscles by avoiding the Valsalva
manoeuvre, usually expressed as ‘not pushing down’, but rather breathing shallowly.

Answers for 573

Option 4

Day 14. This is the middle of the cycle, when ovulation is just occurring;

fluid vaginal secretions favour passage of spermatozoa; if the ovum is fertilized it will be
ready to implant in about a week when the endometrium will be at its most receptive.

Option 1

Day 0. The menstrual cycle is timed from when the patient ﬁrst notices the

menstrual discharge.

Option 4

Day 14. The sudden peaking of the level of luteinizing hormone initiates

ovulation; at this stage the level of oestradiol is falling from its initial peak in the prolife-
rative phase; the level of progesterone is about to start rising steeply.

Option 2

Day 4. The menstrual discharge lasts around four days on average.

Option 5

Day 21. At this stage progesterone is having its maximal effect and the

endometrium is at its most receptive; in the absence of a fertilized ovum the progesterone
level will fall leading to menstruation; if an ovum implants, the gonadotrophic hormone
it produces will stimulate the corpus luteum to maintain and increase secretion of proges-
terone so maintaining the endometrium and the pregnancy.

Answers for 574

Option 3

Seminiferous tubules. This is where the spermatozoa originate and begin

their development.

Option 1

Leydig cells. These are the interstitial cells between the seminiferous tubules.

Option 4

Epididymis. This is the main storage and maturation site.

Option 5

Seminal vesicles. These contribute about two-thirds of the ejaculate volume;

the alkalinity protects the sperm against vaginal acidity and the fructose is a source of
energy.

Option 7

Vas deferens. This transports the spermatozoa under the influence of sym-

pathetic stimulation of the smooth muscle in its wall.

EMQ

Reproductive system – questions

243

EMQ Question 575

For each stage of pregnancy A–E, select the most appropriate option from the following list of
months.

1. Month one.

2. Month two.

3. Month ﬁve.

4. Month eight.

The levels of oestradiol and progesterone are around their maximum; the level of chor-
ionic gonadotrophin is submaximal.

Morning sickness is relatively mild, if present; joint discomfort is not usually a problem
either.

The levels of oestradiol, progesterone and chorionic gonadotrophin are all rising rapidly.

The level of chorionic gonadotrophin is approaching its maximum; the levels of oestrad-
iol and progesterone are well below their maximum.

Heartburn from regurgitation of gastric acid to the oesophagus is favoured by a marked
loss of smooth muscle tone in the lower oesophagus and by a marked rise in intra-
abdominal pressure.

EMQ Question 576

For each of the phases of the female life cycle A–E, select the most appropriate option from
the following list of ages.

1. 10–15 years.

2. 15–20 years.

3. 20–25 years.

4. 30–35 years.

5. 40–45 years.

6. 50–55 years.

7. 60–65 years.

The risk of having a baby with the major genetic abnormality of Down’s syndrome is
around its maximum.

Fertility is at its maximum and the complications of pregnancy at a minimum.

The chances of natural conception are almost zero; the level of gonadotrophic hormones
is around its maximum.

Secondary sexual characteristics usually begin to appear at this age.

The risk of coronary artery disease is now close to the male level; bone density is likely
to have decreased markedly.

EMQ

244

Reproductive system – answers

Answers for 575

Option 4

Month eight. In the last trimester (3-month period) of pregnancy, the hor-

mones sustaining pregnancy are having their maximal effect; the maximal level of chor-
ionic gonadotrophin occurs in the ﬁrst trimester when it is maintaining the corpus luteum.

Option 3

Month ﬁve. The middle trimester tends to have the least discomfort; morn-

ing sickness has usually subsided and the physical effects of a relatively huge uterus in
the last trimester are not yet marked.

Option 1

Month one. The gonadotrophin rises rapidly to produce the corpus luteum

essential in the ﬁrst trimester, and the corpus luteum rapidly increases its activity to ini-
tiate the major changes of pregnancy via oestradiol and progesterone.

Option 2

Month two. The middle of the ﬁrst trimester is the mirror image of the last

trimester in terms of these hormones.

Option 4

Month eight. Regurgitation is favoured by relaxation of the lower oesopha-

geal sphincter, particularly by progesterone and by the concomitant surge in uterine size
and intra-abdominal pressure; both of these effects subside dramatically on delivery of the
baby, and so does the heartburn.

Answers for 576

Option 5

40–45 years. This is the last epoch with a moderate fertility; by this time the

primordial ova are four decades old.

Option 3

20–25 years. In both sexes most physical characteristics are around the

optimal.

Option 6

50–55 years. A minute number of conceptions take place around the age of

50; nearly all women have reached the menopause with its surge of gonadotrophins
directed at the senescent gonads.

Option 1

10–15 years. Changes in fat and hair distribution, the onset of menstruation

(menarche) and the adolescent growth spurt usually begin in this epoch.

Option 7

60–65 years. Some 15 years after the menopause these changes are asso-

ciated with withdrawal of oestrogens and progesterone; many women take hormonal
replacement therapy during this period; it relieves hot flushes and other symptoms which
may be related to the surge in gonadotrophins; some protection against coronary artery
disease and osteoporosis can be balanced against adverse long-term effects.

EMQ

GENERAL QUESTIONS

245

MCQs

Questions 577–582

577. Ultrafiltration

Separates the colloidal contents of a solution from the crystalloid contents.

Is involved in the movement of water and electrolytes across cell membranes.

Is involved in the formation of tissue fluid by the capillaries.

Is involved in the formation of glomerular ﬁltrate by the kidneys.

Is involved in the formation of cerebrospinal fluid by the choroid plexuses.

578. The Fick principle enables

Blood flow through an organ to be calculated if organ uptake (U), arterial concentration
(A) and venous concentration (V) are known for a given substance.

Cardiac output to be calculated by injecting an indicator into the pulmonary artery and
monitoring its concentration downstream in a systemic artery.

Renal plasma flow to be calculated using PAH as the substance measured.

Cardiac output to be estimated using the lungs as the organ and carbon dioxide as the
substance measured.

Cerebral blood flow to be measured using nitrous oxide as the substance taken up by
the brain.

579. Mitochondria

Have membranes similar to the cell membrane.

Are the chief site for protein synthesis.

Are the chief sites for generation of ATP.

Are more numerous in brown than in white fat cells.

Are absent near the membranes of actively secreting cells.

580. Sleep is associated with

An alpha rhythm in the electroencephalogram.

Increased activity in the reticular activating system.

A high level of vagal tone to the heart.

Grinding movements of the teeth.

A rise in central body temperature.

581. During the Valsalva manoeuvre (forced expiration with glottis closed)

Pressure rises in the urinary bladder.

The initial rise in arterial pressure coincides with a fall in the rate of venous return.

Cardiac output rises.

Heart rate slows.

Peripheral resistance rises.

582. Jejunal mucosal cells are similar to proximal convoluted tubular cells in

that both

Absorb glucose by a process linked with sodium absorption.

Absorb chloride ions actively.

Absorb amino acids actively.

Are rich in mitochondria.

Possess microvilli on their luminal border.

MCQ

246

General questions – answers

Answers

577.

True

It depends on pore size and hydrostatic pressure gradients; colloids are larger par-
ticles than crystalloids.

False

Substances cross cellular walls by active transport or down electrochemical gra-
dients; hydrostatic pressure gradients are not involved.

True

An outward hydrostatic pressure gradient exists at the arterial end of the capil-
lary.

True

The pressure gradient across glomerular capillary walls is greater than that in
other capillaries.

True

But active secretion is also involved in the formation of CSF.

578.

True

From the principle, U

⫽F (A⫺V), so F⫽U/(AV).

False

This method is related to the indicator dilution rather than the Fick principle.

True

Uptake

⫽urine volume⫻urine concentration, V⫽zero; the formula is then the

same as for PAH clearance.

True

Either oxygen or carbon dioxide can be the substance measured.

True

The Kety method to measure cerebral blood flow uses the Fick principle.

579.

True

Both membranes have the same lipid bilayer structure.

False

This applies to the ribosomes.

True

ATP is formed by oxidative phosphorylation.

True

Brown fat cells can generate energy, and hence heat, more rapidly.

False

They are concentrated where most energy is required.

580.

False

The alpha rhythm disappears during sleep.

False

Activity decreases; increased activity is associated with alertness.

True

This maintains a slow heart rate during sleep.

True

Teeth-grinding is associated with REM sleep and is called bruxism.

False

This tends to drop during the early hours of sleep.

581.

True

Due to the rise in intra-abdominal pressure.

True

Both result from the sudden initial rise in intrathoracic pressure.

False

It falls due to the reduced venous return.

False

It rises to compensate for a falling arterial pressure.

True

Another reflex compensatory mechanism to restore arterial pressure.

582.

True

In both cases, glucose absorption is blocked by phlorhizin.

False

In both, these follow passively the absorption of sodium.

True

Again the process requires active absorption of sodium.

True

Both expend considerable energy.

True

The two types of cell have very similar functions.

MCQ

General questions – questions

247

Questions 583–589

583. Exercise which doubles the metabolic rate is likely to at least double the

Oxygen consumption.

Cardiac output.

Stroke volume.

Arterial P

Minute volume.

584. The endoplasmic reticulum

Is a complex system of intracellular tubules.

Is a component of the Golgi apparatus.

Has a membrane structure similar to the cell membrane.

Is associated with ribonucleoprotein.

Is well developed in secretory cells.

585. In bone

Osteoclasts are responsible for bone resorption.

Osteoclasts are inhibited by parathyroid hormone.

Maintenance of normal calcium content depends on exposure to mechanical stress.

Strontium ions may substitute for calcium ions.

The width of the epiphyseal plate is an index of its growth rate.

586. The standard deviation of a series of observations

Is related to the scatter of the observations.

Is such that about 95 per cent of observations lie within one standard deviation of the
mean.

Should be calculated only if observations are normally distributed.

Is a measure of the signiﬁcance of the observations.

Is a more valid expression of scatter than is the absolute range for small numbers of
observations, e.g. less than ﬁve.

587. Human circadian (24-hour) rhythms

Are triggered totally by external (exogenous) factors.

Depend more on the integrity of the cerebral cortex than of the hypothalamus.

Adapt within 48 hours on changing from day to night shift work.

For melatonin secretion produce high night-time and low day-time levels of the hor-
mone.

For the eosinophil count produce peak values around midday.

588. The mammalian cell membrane

Is seen as an optically dense line using light microscopy.

Consists mainly of protein.

Is more permeable to fat- than to water-soluble particles.

Contains enzymes.

Contains the receptors for steroid hormones.

589. During early inspiration there is an increase in

Heart rate.

Central venous pressure.

Intrapulmonary pressure.

Abdominal girth.

Afferent impulse trafﬁc in the vagus nerves.

MCQ

248

General questions – answers

Answers

583.

True

Oxygen consumption is directly related to metabolic rate.

False

This rises more slowly than metabolic rate because tissue O

extraction increases.

False

Since heart rate rises, stroke volume does not rise in proportion to metabolic rate.

False

This is little changed.

True

This rises proportionately more than metabolic rate.

584.

True

It is analogous to the sarcoplasmic reticulum in muscle cells.

False

The Golgi apparatus differs in structure, function and location in the cell.

True

As do mitochondria.

True

RNA is found in the ribosomes which are attached to the cytoplasmic side of the
tubules in rough endoplasmic reticulum and are responsible for protein synthe-
sis.

True

It is the site of hormone and enzyme synthesis.

585.

True

They contain an acid phosphatase.

False

They are stimulated to resorb bone with release of calcium ions.

True

Calcium is released from bone during bed rest and inactivity.

True

This may subject bones to increased radioactivity.

True

The epiphyseal plate is relatively wide during childhood.

586.

True

It increases as scatter increases.

False

This is true for two standard deviations; for one standard deviation it is 66 per
cent.

True

Otherwise (B) above does not hold.

False

It is only a description of the scatter of observations.

False

It should not be calculated for very small numbers of observations.

587.

False

External triggers modulate an endogenous clock.

False

The hypothalamus is thought to be the location of the endogenous clock.

False

Adaptation takes about a week or longer.

True

Melatonin given at bedtime has been used to allay the circadian rhythm distur-
bances of sleep with jet-lag.

False

The peak is at night when cortisol level is minimal.

588.

False

It is beyond the resolution of the light microscope.

False

It consists mainly of lipid.

True

Fat-soluble particles dissolve easily in the lipid matrix.

True

These are involved in active transport.

False

Steroid hormones cross the membrane and act intracellularly.

589.

True

This is part of the cycle of respiratory sinus arrhythmia.

False

It decreases due to expansion of the great veins.

False

It falls due to expansion of the thoracic cage.

True

Due to descent of the diaphragm.

True

From stretch receptors in the lung mediating the Hering–Breuer reflex.

MCQ

General questions – questions

249

Questions 590–596

590. Lysosomes

Are membrane-bound organelles in the cytoplasm.

Contain enzymes known as lysozyme.

Are present in serous salivary glands.

Enable neutrophil granulocytes to digest phagocytosed material.

Can digest cellular contents.

591. On lying down there is a decrease in the

Central venous volume.

Total systemic peripheral resistance.

Ventilation/perfusion ratio in lung apices.

Vital capacity.

Rate of formation of urine.

592. One mole of calcium ion

Is equivalent to two osmoles of calcium.

Has the same mass as two equivalents of calcium ion.

Is present in one litre of a normal solution of calcium ions.

Weighs 40 grams.

Depresses the freezing point of water to the same extent as one mole of sodium ion.

593. The Valsalva manoeuvre is followed by a decrease in

Intrapleural pressure.

Intra-abdominal pressure.

Cardiac output.

Arterial blood pressure.

Heart rate.

594. Carbonic anhydrase has a role to play in the formation of

HCl by the parietal cells of the stomach.

Carbaminohaemoglobin.

Cerebrospinal fluid in the choroid plexuses.

Bicarbonate by the pancreas.

Aqueous humour by the ciliary bodies.

595. Sinus arrhythmia

Refers to the cyclical changes in blood pressure that accompany the respiratory cycle.

Can be observed in normal people.

Has a greater amplitude in old than in young people.

Is mediated mainly through sympathetic nerves to the heart.

Can be used as an index of autonomic nerve function.

596. Membrane ion channels

Consist mainly of carbohydrate and lipid.

Have a speciﬁc structure for each ion species.

For sodium may be blocked by tetrodotoxin.

May be opened by a given change in transmembrane potential.

Remain open as long as the activating signal is present.

MCQ

250

General questions – answers

Answers

590.

True

They are present in most cells.

True

Lysozyme breaks down organic structures.

True

Lysozyme in saliva helps to destroy ingested bacteria.

True

The granules are examples of lysosomes.

True

This is responsible for decomposition of tissues after death.

591.

False

Volume expands as blood shifts from veins in the lower extremities to the chest.

True

A reflex response to an increased central blood volume.

True

Apical perfusion increases during recumbency.

True

Due to vascular distension in the lungs and pushing up of the diaphragm.

False

An increase in central blood volume results in increased urine formation.

592.

False

One mole of any ion in solution exerts one osmole of osmotic pressure.

True

Because calcium is divalent.

False

A normal solution has one equivalent weight of ion per litre.

True

This is the atomic weight in grams.

True

1 osmole of a substance in 1 litre of water depresses the freezing point by 1.86°C.

593.

True

It returns to its normal negative value.

True

It also returns to normal.

False

It rises as blood surges back to the central circulation.

False

It rises due to the great increase in cardiac output.

True

A reflex response to the surge in arterial pressure.

594.

True

It facilitates H

⫹

and HCO

⫺

formation from H

O and CO

and H

⫹

is secreted.

False

Carbaminohaemoglobin is formed when CO

combines directly with amino

groups of the globin component of haemoglobin.

False

Blockade of the enzyme does not affect CSF formation.

True

It facilitates H

⫹

and HCO

⫺

formation from CO

and H

O and HCO

⫺

is secreted.

True

Blockade of the enzyme reduces the rate of formation of aqueous humour. It may
be used to lower intraocular tension in patients with glaucoma.

595.

False

It refers to the cyclical changes in heart rate that accompany the respiratory
cycle.

True

It is a normal, harmless phenomenon.

False

It decreases in amplitude with age.

False

It is mediated by vagal nerves and abolished by vagal blockade with atropine.

True

It is impaired in vagal autonomic neuropathy.

596.

False

They are usually proteins.

False

There is usually a family of channels for each ion species.

True

This toxin from the puffer ﬁsh speciﬁcally blocks sodium channels.

True

These channels are ‘voltage-gated’ channels; ‘ligand-gated’ channels are opened
by chemical substances such as acetylcholine.

False

They close automatically after a certain interval.

MCQ

General questions – questions

251

Questions 597–603

597. The hydrogen ion concentration in a solution

Equals the hydroxyl ion concentration at pH 7.

Rises with increasing acidity.

Of pH 5 is 100 times greater than that in a solution of pH 7.

Is inversely related to the hydroxyl ion concentration.

Is approximately doubled if the pH falls by 0.3 units.

598. The human cell nucleus

Has a membrane which is permeable to nucleic acid.

In somatic cells contains 44 chromosomes.

Stores its genetic material in the nucleolus.

Has a skeleton of ﬁne ﬁlaments.

Is essential for cell division.

599. Athletic training leads to an increase in the

Ratio of lean body mass to body fat.

Resting vagal tone.

Resting stroke volume.

Maximal oxygen consumption.

Blood lactate level for a given level of work.

600. The total osmotic pressure of human plasma is

About 25 mmHg.

Similar to that of 0.9 per cent saline.

Similar to that of 0.9 per cent glucose solution.

Opposing the tendency of fluid to leave capillaries.

Equal to that of intracellular fluid.

601. With increasing age there is a fall in the

Arterial pulse pressure.

Ability to detect smells.

Ability of the kidneys to concentrate urine.

Residual volume of the lungs.

Fasting blood glucose concentration.

602. Ingestion of protein

Raises metabolic rate more than ingestion of equally caloriﬁc amounts of fat or carbo-
hydrate.

Tends to lower the pH of urine.

Permits the body to synthesize the essential amino acids.

Yields more toxic metabolites than fat or carbohydrate.

Should exceed 2 g/kg body weight/day to satisfy normal body requirements.

603. Drinking a litre of water

Increases secretion of antidiuretic hormone.

Reduces the plasma sodium concentration.

Causes more osmolar change in portal venous than in systemic venous blood.

Causes body cells to shrink.

Decreases the speciﬁc gravity of the body.

MCQ

252

General questions – answers

Answers

597.

True

This is the neutral pH of water.

True

The pH falls.

True

pH is minus log

hydrogen ion concentration.

True

The product of these ionic concentrations is constant.

True

Log 2

⫽0.301.

598.

True

Messenger RNA crosses the nuclear membrane.

False

The total is 46; i.e. 44

⫹XX or XY.

False

The nucleolus is a condensation of RNA; the genetic material is in chromosomes.

True

These are attached to the nuclear membrane.

True

For example, red blood cells cannot divide.

599.

True

Skeletal muscle bulk increases with activity more than fat.

True

This explains the slow pulse rate seen in athletes.

True

This maintains resting cardiac output with the slower heart rate.

True

This is a good index of physical ﬁtness.

False

Due to greater capacity to deliver oxygen to muscle, the reverse is true.

600.

False

It is about 5500 mmHg (25 mmHg is the colloid osmotic pressure).

True

Both have an osmolality around 290 mosmol/litre.

False

It is similar to 5 per cent glucose which contains about the same number of par-
ticles.

False

The colloid osmotic pressure does this; the crystalloids pass capillary walls freely
and exert no effective pressure gradient across the capillary wall.

True

Intracellular and extracellular fluid have the same osmolality.

601.

False

It rises with loss of arterial elasticity.

True

The condition is called hyposmia.

True

Due to a fall in maximal renal medullary osmolality.

False

It increases as small airways collapse more readily.

False

It rises as glucose homeostasis loses efﬁciency.

602.

True

Due, perhaps, to the additional metabolic work in processing protein in the body.

True

Protein is the main dietary source of the acidic residues excreted by the kidney.

False

Essential amino acids cannot be synthesized in the body.

True

These metabolites, normally detoxiﬁed in the liver, may cause hepatic encepha-
lopathy in hepatic failure.

False

One gram per kilogram is adequate.

603.

False

It suppresses secretion of antidiuretic hormone.

True

Osmolality is reduced in all the body fluid compartments.

True

The water is absorbed via the portal vein.

False

They swell as water is drawn in osmotically.

False

It moves it upwards from its value of less than 1.0.

MCQ

General questions – questions

253

Questions 604–610

604. The Golgi apparatus is

Found in all eukaryotic cells.

A collection of complex tubules and vesicles.

Well developed in cells with secretory activity.

Associated with endoplasmic reticulum.

Not conspicuous in neurones.

605. An acid–base buffer system

Can be a mixture of a weak acid and its conjugate base.

Can be a solution of sodium and bicarbonate ions.

Prevents any change in pH when acid is added.

Works best when acid and base are equal in concentration.

With pK

⫽4 would be a better blood buffer than one with pK⫽6.

606. Rapid eye movement (REM) sleep is

Associated with EEG waves of high amplitude.

Less common after a period of sleep deprivation.

Associated with a high level of general muscle tone.

Ineffective in relieving fatigue.

A more frequent component of sleep in the elderly than in the young.

607. From childhood to old age

There is a steady decrease in total sleeping time per day.

Deep (stage 4) sleep increases as a percentage of total daily sleep.

Brain mass steadily decreases.

Body water decreases as a percentage of body mass.

Sleep becomes less aggregated into a single sleeping period.

608. Immersion of an upright adult to chest level in water increases the

Water pressure on the feet to nearer 100 than 20 mmHg.

Thoracic blood volume.

Total peripheral resistance.

Sodium excretion in the urine.

Transmural pressure in the blood vessels of the feet.

609. In the days following a major surgical operation there is

An increase in plasma cortisol level.

A negative nitrogen balance.

Potassium retention.

A negative sodium balance.

A decreased tendency for the blood to clot.

610. The graph of body mass (ordinate) versus age

Normally steepens from birth to ﬁve years.

Normally steepens during secondary sexual development.

Steepens earlier than usual with precocious puberty.

Is parallel for males and females.

Deviates towards the normal curve with successful treatment of a child with dwarﬁsm.

MCQ

254

General questions – answers

Answers

604.

True

Usually close to the nucleus.

False

It is a collection of about six flattened, membrane-enclosed sacs stacked together.

True

Secretions are packaged into vesicles in the Golgi apparatus.

True

Proteins formed by the granular endoplasmic reticulum fuse with the membranes
of the Golgi sacs before being packed into vesicles and released into the cyto-
plasm.

False

Neurones are secretory cells.

605.

True

Or a mixture of a weak base with its conjugate acid.

False

It can be a mixture of carbonic acid and bicarbonate ions.

False

It minimizes, but does not prevent, pH change.

True

⫽pK⫹log [base]/[acid]; log 1⫽0.

False

pK should be near blood pH, which is 7 4.

606.

False

The waves are of high frequency and low amplitude.

False

REM sleep increases proportionately after sleep deprivation.

False

General muscle tone is reduced.

False

Fatigue is poorly relieved if REM sleep is prevented.

False

It occurs less frequently in the elderly.

607.

True

The elderly seem to need less sleep.

False

This percentage also falls steadily.

False

It increases markedly in early childhood.

True

From over 80 per cent in the fetus to less than 50 per cent in old age.

True

Though aggregation increases in infancy, it later declines steadily.

608.

True

100 mmHg is equivalent to 1.36 metres of H

True

Due to pressure on capacity vessels in the lower body.

False

Increased central blood volume reflexly lowers resistance.

True

Increased central blood volume causes diuresis, perhaps via atrial natriuretic hor-
mone.

False

It decreases transmural pressure and so protects the vessels against distension due
to gravitational forces.

609.

True

This is essential for normal recovery.

True

Cortisol breaks down protein to form glucose.

False

Potassium excretion increases.

False

There is a positive sodium balance.

False

The clotting tendency increases for about ten days.

610.

False

It becomes less steep over this period.

True

This is the adolescent growth spurt.

True

Sex hormones produce an early adolescent growth spurt.

False

Females show an earlier adolescent growth spurt.

True

The faster than normal growth rate is an important sign of appropriate treatment.

MCQ

General questions – questions

255

Questions 611–616

611. Obesity can be treated successfully by

Diuretic drugs.

Supplementing the normal diet with slimming foods.

Conﬁning the diet to foods of low caloriﬁc value.

Increasing exercise without increasing food intake.

Reducing food intake relative to energy expenditure.

612. An injection of atropine typically produces a decrease in

Resting heart rate.

Skeletal muscle strength.

Salivary flow.

Mucus secretion in the airways.

Impulse transmission at autonomic ganglia.

613. In percentage terms, arterial P

CO2

is more affected than arterial O

con-

tent by

Carbon monoxide poisoning.

Anaemia.

A 20 per cent fall in inspired P

Ascent to 2000 metres (about 6500 feet) above sea level.

Increasing the oxygen pressure in the air breathed to three atmospheres.

614. Polycythaemia is caused by

Lung disease which causes a fall in oxygen saturation in arterial blood.

Heart disease which causes a right to left shunt.

Chronic renal failure.

Pregnancy.

High doses of vitamin B

615. When kept afloat by a life jacket, survival time in water at 15°C is

Usually 12–24 hours.

Limited by muscular fatigue.

Extended if many layers of clothing are worn.

Extended by swimming gently rather than floating motionless.

More prolonged in fat than in thin persons.

616. An organ transplant is less likely to be rejected if the recipient

Is given glucocorticoid treatment.

Has previously received a skin graft from the same individual.

Is an infant.

Is an identical rather than a non-identical twin of the donor.

Has the same blood group as the donor.

MCQ

256

General questions – answers

Answers

611.

False

This reduces body water but not body fat.

False

This makes the person fatter.

False

This is ineffective unless the total energy intake is reduced.

True

Energy expenditure increases; energy intake is unchanged.

True

This is the only effective long-term treatment.

612.

False

It increases due to blocking of acetylcholine’s action at the sinus node.

False

Atropine does not block acetylcholine’s action on skeletal muscle.

True

Salivation is stimulated by cholinergic autonomic nerves.

True

This may be useful during surgical operations.

False

This cholinergic transmission is resistant to atropine.

613.

False

Pressure is little affected but content is decreased.

False

Pressure is normal but content decreased.

True

Arterial P

is reduced but content falls by only 3 per cent or so because of the

shape of the oxygen dissociation curve.

True

This causes a fall of about 20 per cent in inspired oxygen pressure.

True

This causes a huge rise in P

but a relatively small increase in arterial oxygen

content since the haemoglobin is almost fully saturated when breathing oxygen
at 100 mmHg pressure.

614.

True

A fall in the O

content of arterial blood stimulates production of erythropoietin.

True

This also reduces the oxygen content of arterial blood.

False

Anaemia is common in chronic renal failure due to damage to the erythropoietin-
producing cells.

False

The increase in plasma volume causes a fall in red cell count.

False

This prevents megaloblastic anaemia but does not raise red cell concentration
above normal.

615.

False

It is usually under two hours.

False

It is limited by hypothermia.

True

This improves insulation by trapping layers of water around the body to form a
stable microclimate.

False

Swimming increases heat loss by disturbing the microclimate.

True

Due to better thermal insulation by the superﬁcial fat.

616.

True

This suppresses immune reactions.

False

This would sensitize the immune response.

True

The immune system is less well-developed in infants.

True

Only identical twins have identical genes and hence identical tissue antigens.

True

However, blood group compatibility is not a reliable index of tissue compatibil-
ity.

MCQ

General questions – questions

257

Questions 617–622

617. Obesity

Is associated with reduced life expectancy.

Is one cause of diabetes mellitus.

In parents is associated with obesity in their children.

Is usually due to an endocrine disorder.

May be treated by surgical removal, or bypass, of part of the small intestine.

618. Sudden exposure to an atmospheric pressure of 100 mmHg (13 kPa), as

might occur with loss of aircraft cabin pressure at around 15 000 m alti-
tude, causes

Rupture of the eardrums by outward bulging.

The appearance of gas bubbles in joints and lungs.

No serious fall in the alveolar oxygen pressure if the person is breathing pure oxygen.

Expansion of gas in closed spaces in the body.

Gradual loss of consciousness in 10–15 minutes due to hypoxia.

619. Restoration of the blood volume after haemorrhage is aided by

Contraction of venous reservoirs.

A fall in capillary pressure in certain vascular beds.

Arteriolar vasoconstriction.

Mobilization of intracellular fluid into the circulation.

An increase in the osmotic pressure of the plasma proteins.

620. A transplanted kidney is

Able to maintain the recipient’s blood urea at normal levels.

Able to correct the anaemia of chronic renal failure.

Probably being rejected if the glomerular ﬁltration rate is falling rapidly.

Probably being rejected if there is a sharp rise in body temperature in the absence of
infection.

Probably being rejected if the urinary volume is low and the osmolality high.

621. Helium is used to replace nitrogen in gas breathed by divers because it

Is more soluble in body fluids.

Diffuses through the tissues more rapidly.

Causes less depression of cerebral function.

Diminishes the work of breathing relative to nitrogen.

Combines less readily with haemoglobin.

622. Someone who has received an electric shock causing ventricular fibrilla-

tion

Loses consciousness in less than a minute.

Has a reduction in cardiac output of about 50 per cent.

Has a rapid but weak carotid pulse.

Should be given external cardiac massage after removal from the electrical contact.

Should not be given artiﬁcial ventilation until the ventricular ﬁbrillation has been
reversed.

MCQ

258

General questions – answers

Answers

617.

True

Being 20 per cent overweight reduces life expectancy by about 20 per cent.

True

The diabetes may then be cured by weight reduction.

True

Both genetic and environmental factors may operate.

False

This is a very rare cause.

True

This leads to malabsorption, but the resulting malnutrition may have side effects.

618.

True

Ambient pressure drops much faster than middle ear pressure.

True

This is a manifestation of decompression sickness.

False

More than half of the total alveolar pressure will be taken up by carbon dioxide
and water vapour.

True

This must happen from Boyle’s law.

False

Sudden severe hypoxia of this order causes unconsciousness in less than a
minute.

619.

False

This redistributes but does not increase blood volume.

True

This favours absorption of tissue fluid into the circulation.

True

This leads to the fall in downstream capillary pressure.

False

Haemorrhage does not increase the osmolality of extracellular fluid.

False

Colloid osmotic pressure falls as tissue fluid is drawn into the circulation.

620.

True

One normal kidney can do this.

True

By replacing the deﬁcient erythropoietin.

True

This suggests nephron damage.

True

This, like a raised ESR and granulocyte count, suggests tissue destruction.

False

A high urinary osmolality suggests excellent renal function.

621.

False

Being less soluble, less goes into solution during compression so there is less
bubble formation during decompression.

True

This also reduces the time needed for decompression.

True

It is less narcotic than nitrogen.

True

It is less viscous than nitrogen.

False

Neither combine with haemoglobin.

622.

True

Due to the abrupt fall in cerebral blood flow.

False

Cardiac output is nil.

False

There is no cardiac output; hence no pulse.

True

This will prevent brain damage until the ﬁbrillation has been reversed.

False

Artiﬁcial ventilation must accompany cardiac massage to avoid brain damage.

MCQ

General questions – questions

259

Questions 623–629

623. A patient with fever

Has warm extremities as central temperature rises.

Has a raised basal metabolic rate.

Shows evidence of altered hypothalamic function.

Loses the capacity for reflex thermoregulation.

May develop heat stroke if the core temperature rises to 40

624. Acidosis in a patient may lead to

Increased urinary excretion of potassium.

Hypoventilation.

A blood pH of less than 5.5.

A urinary pH of less than 5.5.

Tetany.

625. When a patient inherits a disease as a recessive autosomal character

One of the parents of the patient will exhibit the disease.

All of the children of the patient will exhibit the disease.

All of the children of the patient will be carriers.

Both parents of the patient must carry the recessive character.

Subsequent siblings have a 50 per cent risk of the disorder.

626. If treatment A is superior to treatment B in certain respects (with a P

value less than 0.01) it can be concluded that

A given patient’s chances of improvement by treatment A are 99 per cent.

The likelihood that the observed difference between treatments A and B is due to chance
is less than 1 per cent.

The observed superiority is statistically signiﬁcant.

At least 100 patients were studied.

Treatment A should now be substituted for treatment B.

627. A low serum potassium level

Can be suspected from the appearance of the ECG.

Can result from repeated vomiting of gastric contents.

Indicates that total body potassium is low.

May be a consequence of aldosterone deﬁciency.

Impairs gut motility.

628. A rise in the osmolality of extracellular fluid may lead to

Thirst.

Increased water reabsorption in the proximal convoluted tubules.

Release of vasopressin.

A fall in intracellular fluid volume.

Suppression of sweat secretion.

629. Maximal exercise leads to an increase in

Systolic blood pressure.

Total peripheral resistance.

Blood lactic acid.

Tissue fluid formation in active muscles.

Urinary output.

MCQ

260

General questions – answers

Answers

623.

False

Reflex vasoconstriction causes cold hands at this stage.

True

The raised body temperature speeds metabolism.

True

The ‘set point’ for temperature regulation is raised.

False

Core temperature is maintained around the raised level.

False

The core temperature needs to rise to about 43

C before heat stroke develops.

624.

False

Hydrogen ions compete with potassium for secretion.

False

Ventilation is increased in acidosis.

False

This level would be fatal.

True

Urinary pH may fall below 5.0.

False

Acidosis reduces the risk of tetany by decreasing protein afﬁnity for calcium.

625.

False

Both parents are usually healthy.

False

They are likely to be normal due to the dominant normal gene from the spouse.

True

All will receive the recessive gene from the patient.

True

Only thus will the patient have a homozygous genotype.

False

From simple Mendelian laws the chances are 25 per cent.

626.

False

This cannot be concluded from the results given.

True

This is the meaning of P less than 0.01.

True

Conventionally P must then be less than 0.05.

False

This cannot be concluded from the results given.

False

Adverse effects may outweigh the beneﬁt shown.

627.

True

It leads to low voltage T waves.

True

The vomitus is relatively rich in potassium.

False

It is a poor reflector of total body potassium.

False

This favours retention of potassium and a high serum level.

True

It may cause paralytic ileus (paralysis of peristalsis).

628.

True

Due to stimulation of hypothalamic osmoreceptors.

False

Water reabsorption in proximal tubules is not geared to meet body water needs.

True

Impulses from hypothalamic osmoreceptors cause release of pituitary vasopres-
sin.

True

The cells shrink as fluid is drawn out osmotically.

False

Sweat production is not geared to body fluid requirements.

629.

True

Due mainly to the increase in the force of ventricular ejection.

False

This falls markedly due to vasodilatation in muscle, heart and skin.

True

Since the muscles may have to work in anaerobic conditions.

True

This results from the rise in hydrostatic pressure in muscle capillaries.

False

This decreases, probably due to reflex vasoconstriction in the kidneys and
increased release of vasopressin.

MCQ

General questions – questions

261

Questions 630–636

630. Following adaptation to a hot climate there is an increase in

Basal metabolic rate.

Resting cardiac output.

Urinary output.

The ability to lose heat by sweating.

Exercise tolerance.

631. Sudden complete obstruction of the respiratory tract causes

A fall in blood pressure.

Stimulation of central chemoreceptors.

Cyanosis.

Reflex apnoea.

Dilatation of the pupils.

632. Inherited diseases associated with sex-linked recessive genetic disorders

Involve the Y rather than the X chromosome.

Are more common in females than in males.

Are transmitted by the female but not by the male.

May fail to manifest themselves in female carriers.

Include haemophilia.

633. Infants differ from adults in that their

Nitrogen balance is normally positive.

Extracellular fluid volume is a larger proportion of total body water.

Blood contains reticulocytes.

Total peripheral resistance is lower.

Brown fat stores are relatively small.

634. Excessive sweating (hyperhidrosis) in a limb is likely to be relieved by

Blockade of autonomic ganglia with ganglion-blocking drugs.

Blockade of autonomic cholinergic nerve endings with atropine.

Blockade of somatic cholinergic nerve endings with curare.

Blockade of adrenergic nerve endings with phentolamine.

Section of the sympathetic motor nerves supplying the limb.

635. A disease inherited as a dominant autosomal character

Affects males and females equally.

Affects all the children of the affected adult.

Usually prevents reproduction.

Requires that both parents carry the abnormality.

May be transmitted by a carrier who does not manifest the disease.

636. The effects of moving from sea level to an altitude of 5000 metres

include an increase in

Alveolar ventilation.

Blood bicarbonate level.

Appetite for food.

Exercise tolerance.

Simulation of the bone marrow.

MCQ

262

General questions – answers

Answers

630.

False

BMR falls due to a decrease in resting thyroid activity.

True

Partly due to increased thermoregulatory blood flow.

False

Urinary output is usually reduced due to increased water loss by extrarenal
routes.

True

Daily secretion of sweat may rise to several litres.

True

Due mainly to the improved ability to dissipate heat.

631.

False

Blood pressure rises due to reflex stimulation of the heart and peripheral vaso-
constriction.

True

Accumulation of CO

is mainly responsible for the reflex cardiovascular and res-

piratory responses.

True

Deoxygenated haemoglobin appears in the arterial blood.

False

Respiratory effort increases with chemoreceptor stimulation.

True

Part of the generalized sympathetic response to stress.

632.

False

The abnormality is on the X chromosome.

False

Females are protected by the normal X chromosome.

False

Both can transmit a defective X chromosome.

True

Due to protection by a normal X chromosome.

True

Colour blindness is another example.

633.

True

Adults are normally in nitrogen balance.

True

It exceeds intracellular fluid volume.

False

Both infants and adults have reticulocytes in the blood.

False

It is higher; the pressure gradient to cardiac output ratio is much greater.

False

They are relatively much larger.

634.

True

But the side effects are likely to be worse than the disease.

True

Again side effects may be troublesome.

False

This paralyses skeletal muscles without inhibiting sweating.

False

The nerves responsible for sweating are cholinergic.

True

This is an effective therapy.

635.

True

The autosomes are similar for males and females.

False

Half would receive the normal autosome.

False

Such genes are commonly transmitted.

False

If so, it would not be a dominant disorder.

False

Carriers of a dominant character exhibit the disease.

636.

True

Due to stimulation of peripheral chemoreceptors by hypoxia.

False

Bicarbonate is lost in the urine to compensate for the respiratory alkalosis.

False

Loss of appetite (anorexia) is a common complaint in mountain climbers.

False

Exercise tolerance is reduced by the decreased ability to deliver O

to the blood.

True

Due to an increased erythropoietin level.

MCQ

General questions – questions

263

Questions 637–639

637. The ratio of intravascular hydrostatic pressure to colloid osmotic pressure

is greater

In splanchnic than in renal glomerular capillaries.

Than normal in patients with hepatic failure.

Than normal in the systemic capillaries of patients following severe blood loss.

Than normal in capillaries where there is oedema due to venous obstruction.

In systemic than in pulmonary capillaries.

638. Sudden application of cold water to the

Hand causes local vasoconstriction.

Hand causes vasodilation in the opposite hand.

Oesophagus can cause changes in the electrocardiogram.

External auditory meatus causes nausea and nystagmus.

Whole body by immersion causes apnoea.

639. Normal healthy young adults can tolerate loss of half of their

Renal tissue without developing renal failure.

Pulmonary tissue without developing respiratory failure.

Circulating platelets without developing a haemorrhagic tendency.

Seminal sperm count without suffering from infertility.

Liver without developing hepatic failure.

MCQ

264

General questions – answers

Answers

637.

False

It is higher in glomerular capillaries, as is necessary for ﬁltration.

True

Colloid osmotic pressure falls because the liver fails to synthesize enough albu-
min.

False

The reverse is true, causing transfer of tissue fluid into the circulation.

True

Hence excess fluid is forced out of the capillaries into the interstitial spaces.

True

The lower ratio in the lungs normally prevents fluid leak into the alveoli.

638.

True

Due to the direct effect of cold on vascular smooth muscle.

False

Immersion of a hand in cold water provokes general vasoconstriction and a rise
in blood pressure – the cold pressor response.

True

By cooling the myocardium.

True

By inducing currents in endolymph which stimulate vestibular receptors.

False

By stimulating uncontrollable gasping under water, it may result in drowning.

639.

True

Normal function can be maintained with one kidney.

True

Though maximum exercise tolerance is reduced, considerable exertion is possible.

True

The platelet count must fall by more than 75 per cent before bleeding problems
arise.

True

Infertility is unlikely unless the count falls to around a quarter of the normal
value.

True

In short, most body functions carry at least a 50 per cent reserve in the young
adult.

MCQ

GENERAL QUESTIONS

265

EMQs

Questions 640–649

EMQ Question 640

For each of the intracellular organelles A–E, select the best option from the following list of
descriptions.

1. Sites of protein synthesis rich in RNA.
2. Intracellular membrane-bound structures containing enzymes that can destroy most

cellular structures.

3. Granules in a layer produced by high-speed centrifugation of cells.
4. Structures lying close to the nucleus responsible for organizing the microtubular

systems.

5. Membrane-bound organelles associated with numerous enzymes that catalyse a

variety of anabolic and catabolic reactions.

Lysosomes.

Centrosomes.

Peroxisomes.

Microsomes.

Ribosomes.

EMQ Question 641

For each of the varieties of acid–base disturbance A–E, select the best option for a possible
cause from the following list.

1. Sudden laryngeal obstruction.

2. Severe chronic respiratory disease.

3. Chronic renal failure.

4. Mountain climbing.

5. Severe diarrhoea.

Uncompensated respiratory acidosis.

Uncompensated metabolic acidosis.

Compensated respiratory acidosis.

Uncompensated respiratory alkalosis.

Compensated metabolic acidosis.

EMQ

266

General questions – answers

Answers for 640

Option 2

Intracellular membrane-bound structures containing enzymes that can

destroy most cellular structures. The postmortem breakdown of the lysosomal membranes
releases lysosomal enzymes that autolyse (cause self-destruction of) the cell.

Option 4

Structures lying close to the nucleus responsible for organizing the microtu-

bular systems. Centrosomes are made up of two centrioles. At mitotic division the centro-
somes are duplicated and one goes to each end of the mitotic spindle. The microtubules
they control allow movement within the cell.

Option 5

Membrane-bound organelles associated with numerous enzymes that cata-

lyse a variety of anabolic and catabolic reactions. They are involved in the oxidation of
some long chain fatty acids. Drugs that can modify peroxisome behaviour are being used
in the attempt to lower lipid levels in the blood.

Option 3

Granules in a layer produced by high-speed centrifugation of cells. This is

the generic name for the cellular organelles brought down by high-speed centrifugation.

Option 1

Sites of protein synthesis rich in RNA. Ribosomes can be attached to the

endoplasmic reticulum where they synthesize proteins such as hormones.

Answers for 641

Option 1

Sudden laryngeal obstruction. The obstruction leads to a rapid rise in P

before the kidneys can compensate by generating bicarbonate thus raising the blood
bicarbonate level.

Option 5

Severe diarrhoea. Severe diarrhoea results in loss of bicarbonate in the stools

and thus to a fall in the blood bicarbonate level.

Option 2

Severe chronic respiratory disease. The raised P

in chronic respiratory dis-

ease may be compensated for by renal generation of bicarbonate to raise the blood bicar-
bonate level.

Option 4

Mountain climbing. The respiratory drive caused by the action of low Po

arterial chemoreceptors washes out CO

. This lowers the P

to cause an alkalosis.

Eventually the kidneys compensate by eliminating more bicarbonate.

Option 3

Chronic renal failure. The fall in blood bicarbonate used in buffering the

acid residues of protein digestion in chronic renal failure is compensated for by an
increased respiratory drive that results in a fall in P

EMQ

General questions – questions

267

EMQ Question 642

For each of the electrical potentials A–E, select the best option for a possible description from
the following list.

1. The graded, non-propagated potential changes across cell membranes induced by

neurotransmitter substances.

2. The voltage gradient between the inside and the outside of a cell.
3. The unstable membrane potentials seen in smooth and cardiac muscle.
4. All or non-propagated potentials in excitable tissues.
5. The graded, non-propagated potential changes seen in sensory end organs.

Action potentials.

Membrane potentials.

Generator potentials.

Pacemaker potentials.

Post-synaptic potentials.

EMQ Question 643

For each of the substances associated with synaptic transmission A–E, select the best option
for its possible function from the following list.

1. A neurotransmitter in the brain involved in determining mood.
2. Involved in the genesis of inhibitory post-synaptic potentials (IPSPs).
3. Involved in the breakdown of catecholamines.
4. A neurotransmitter in the brain involved in basal ganglia activity.
5. Involved in the breakdown of acetylcholine.

Mono amine oxidase (MAO).

Cholinesterase.

Gamma amino butyric acid (GABA).

Dopamine.

Serotonin.

EMQ

268

General questions – answers

Answers for 642

Option 4

All or none-propagated potentials in excitable tissues. Action potentials

travel as a wave of reversed polarity caused by an initial increase in membrane perme-
ability to sodium followed by a slower increase in membrane permeability to potassium.

Option 2

The voltage gradient between the inside and the outside of a cell. This poten-

tial is maintained actively by metabolic processes and disappears if these processes are
poisoned. Resting membrane potentials range from about 60 to about 90 millivolts, neg-
ative inside with respect to outside.

Option 5

The graded, non-propagated potential changes seen in sensory end organs.

When a stimulus is applied to a sensory end organ it causes a non-propagated depolariza-
tion whose size is related to the strength of the stimulus. When the generator potential
reaches the threshold for ﬁring, it gives rise to an action potential that travels along the
axon away from the end organ.

Option 3

The unstable membrane potentials seen in smooth and cardiac muscle. The

membranes of pacemaker cells show an unstable membrane potential that falls spontane-
ously until it reaches the threshold for ﬁring when it gives rise to one or more propagated
action potentials.

Option 1

The graded, non-propagated potential changes across cell membranes

induced by neurotransmitter substances. When an impulse reaches the terminal processes
of a pre-synaptic nerve, it causes neurotransmitter to be released that induces post-
synaptic potentials in the post-synaptic neurone. When the potential reaches the thresh-
old for ﬁring in the post-synaptic nerve an action potential is induced that travels over
the entire membrane of the post-synaptic cell.

Answers for 643

Option 3

Involved in the breakdown of catecholamines. Catecholamines are inacti-

vated by oxidation by the enzyme MAO that is found in some neurones.

Option 5

Involved in the breakdown of acetylcholine. Cholinesterase is found in high

concentration near motor nerve endings in muscle and rapidly hydrolyses acetylcholine
following its release from the nerve endings.

Option 2

Involved in the genesis of inhibitory post-synaptic potentials (IPSPs). GABA

is released from pre-synaptic nerve endings and causes hyperpolarization of the post-syn-
aptic membrane so causing an IPSP.

Option 4

A neurotransmitter in the brain involved in basal ganglia activity.

Degeneration of dopaminergic neurones in the substantia nigra is associated with
Parkinson’s disease.

Option 1

A neurotransmitter in the brain involved in determining mood. Serotonin

containing nerves have been found in the brain stem. Selective serotonin uptake inhibi-
tor drugs are used in the treatment of depression.

EMQ

General questions – questions

269

EMQ Question 644

For each of the items related to body energy A–E, select the best option for its description from
the following list.

1. The increase in energy expenditure

2. A thioester high-energy compound.

following ingestion of food.

3. A method to estimate the metabolic rate.

4. A phosphorolated high-energy

5. The rate of metabolism in a resting subject.

compound.

Measurement of oxygen consumption.

Speciﬁc dynamic action (SDA).

ATP.

BMR.

Acetyl-coenzyme A.

EMQ Question 645

For each variety of reflex A–E, select the best option from the examples in the following list.

1. Nerve-mediated skin vasodilatation

2. The withdrawal reflex.

following skin damage.

3. Salivation on seeing or thinking about

4. The knee jerk.

food.

5. The baroreceptor reflex.

A monosynaptic reflex.

A polysynaptic somatic reflex.

A conditioned reflex.

A visceral unconditioned reflex.

An axon reflex.

EMQ Question 646

For each variety of sensory receptor A–E, select the best option for its adequate stimulus from
the following list.

1. Pain.

2. Angular acceleration of the head.

3. Stretch.

4. Sound waves in the inner ear.

5. Sweet substances in solution.

Muscle spindles.

Bare nerve endings.

Crista ampullaris receptors.

Outer hair cells receptors.

Fungiform papillae receptors.

EMQ

270

General questions – answers

Answers for 644

Option 3

A method to estimate the metabolic rate. The rate of metabolism can be esti-

mated from the oxygen consumption if the respiratory quotient is known.

Option 1

The increase in energy expenditure following ingestion of food. The extra

energy expenditure required to assimilate ingested food into the body is referred to as its
SDA. It is required for all types of food but protein requires the most energy for its assim-
ilation.

Option 4

A phosphorolated high-energy compound. Adenosine triphosphate (ATP) is

widely distributed in the body and much energy is stored in its phosphate bonds. This
energy can be released when required to energy-requiring processes such as muscle
contraction and membrane polarization.

Option 5

The rate of metabolism in a resting subject. The basal metabolic rate is a

measure of total energy expenditure at rest in the post-absorptive state. It can be meas-
ured by measuring oxygen consumption.

Option 2

A thioester high-energy compound. This sulphur containing high-energy

compound is derived from mercaptan. It combines with substances in reactions that would
otherwise require outside energy.

Answers for 645

Option 4

The knee jerk. This is a spinal reflex with two neurones. The afferent nerve

from the muscle spindle synapses with a motor ﬁbre in the anterior horn of the spinal
cord.

Option 2

The withdrawal reflex. This reflex has more than two synapses in the reflex

pathway.

Option 3

Salivation on seeing or thinking about food. This is a learned reflex that can

be reinforced or inhibited by learned experience and involves the cerebral cortex.

Option 5

The baroreceptor reflex. This reflex is inborn and is not modiﬁed by learned

experiences.

Option 1

Nerve-mediated skin vasodilatation following skin damage. An axon reflex

is a local reflex that does not involve the spinal cord. Stimulation of a sensory nerve
receptor results in a local response mediated by a local branch of the sensory nerve.

Answers for 646

Option 3

Stretch. Stretching of the muscle spindles leads to reflex contraction of the

muscle being stretched as in the knee jerk.

Option 1

Pain. These nerve endings are stimulated by stimuli that tend to damage the

tissues in which the bare nerve endings lie.

Option 2

Angular acceleration of the head. The sensory end organs in the crista

ampullaris are stimulated when movement of fluid in the semicircular canals moves the
hair cells in the cupulae.

Option 4

Sound waves in the inner ear. These sensory organs lie in the organ of Corti

and are stimulated when sound waves cause vibrations in the basilar membrane in the
inner ear.

Option 5

Sweet substances in solution. These taste receptors are found towards the

front of the tongue and can detect sweet taste stimuli.

EMQ

General questions – questions

271

EMQ Question 647

For each clinical disturbance A–E, select the best option for its possible cause from the follow-
ing list.

1. Renal failure.

2. Respiratory failure.

3. Heart failure.

4. Peripheral circulatory failure.

5. Liver failure.

Lowered central venous pressure.

A raised plasma bicarbonate level.

Metabolic acidosis and anaemia.

Raised central venous pressure.

A lowered blood urea.

EMQ Question 648

For each region of the brain A–E, select the best option for one of its possible functions from
the following list.

1. Fear and rage reactions.

2. Vision.

3. Alerting reactions.

4. Temperature regulation.

5. Postural reflexes.

The reticular formation.

The substantia nigra.

The hypothalamus.

The limbic system.

The occipital cortex.

EMQ Question 649

For each variety of inhibition in the nervous system A–E, select the best option for its descrip-
tion from the following list.

1. Inhibition produced by the action of neurotransmitters on the terminal processes of

afferent nerves.

2. Inhibition produced by release of transmitters that affect the membrane potential of

efferent neurones.

3. A form of inhibition in which activation of one neural group causes inhibition of

neurones surrounding the activated group.

4. Inhibition of a conditioned reflex by the application of a new stimulus just before the

application of the conditioned stimulus.

5. A state where neurones in the brain and spinal cord are less excitable than normal.

Afferent inhibition.

Central inhibition.

Post-synaptic inhibition.

Pre-synaptic inhibition.

External inhibition.

EMQ

272

General questions – answers

Answers for 647

Option 4

Peripheral circulatory failure. In circulatory failure such as may occur in

severe shock or haemorrhage, the fall in venous return to the heart lowers central venous
pressure.

Option 2

Respiratory failure. The retention of CO

in respiratory failure leads to an

acidosis that is compensated for by generation of bicarbonate by the kidney.

Option 1

Renal failure. In renal failure, failure to excrete acid residues of metabolism

causes acidosis. Anaemia is often seen since erythropoietin is normally manufactured by
the kidneys.

Option 3

Heart failure. In heart failure where the heart cannot pump forward all the

blood being delivered to it, there is a rise in central venous pressure that increases the
diastolic ﬁlling of the heart.

Option 5

Liver failure. The liver is responsible for the deamination of amino acids and

the conversion of the NH

residues into urea.

Answers for 648

Option 3

Alerting reactions. Stimulation of the ascending reticular formation leads to

increased electrical activity in the cortex and results in a state of alertness.

Option 5

Postural reflexes. Diseases affecting this part of the brain such as Parkinson’s

disease result in abnormal distribution of muscle tone. Substantia nigra neurones are
dopaminergic.

Option 4

Temperature regulation. Temperature regulating centres are found in the

hypothalamus.

Option 1

Fear and rage reactions. The limbic region is associated with the emotions.

Option 2

Vision. Visual impulses are conveyed to the occipital cortex in the optic

tracts where they give rise to conscious visual images.

Answers for 649

Option 3

A form of inhibition in which activation of one neural group causes inhibi-

tion of neurones surrounding the activated group. This is seen in the neurones of the occip-
ital cortex where central excitation reduces activity in surrounding neurones.

Option 5

A state where neurones in the brain and spinal cord are less excitable than

normal. A general state of inhibition of excitability of the neurones in the CNS can be
induced by general anaesthetic and other drugs that depress the central nervous system.

Option 2

Inhibition produced by release of transmitters that affect the membrane

potential of efferent neurones. Here the inhibition of the post-synaptic membrane is caused
by the action of pre-synaptic nerve terminals directly on the membrane of the post-syn-
aptic cell body.

Option 1

Inhibition produced by the action of neurotransmitters on the terminal pro-

cesses of afferent nerves. In this case nerve endings of afferent neurones release neuro-
transmitters close to the nerve endings of other neurones to modulate release of
neurotransmitter from them.

Option 4

Inhibition of a conditioned reflex by an application of a new stimulus just

before the application of the conditioned stimulus. Conditioned reflexes can be reinforced
or inhibited by external stimuli given at about the same time as the conditioned stimulus.

EMQ

SPORT AND EXERCISE PHYSIOLOGY

273

MCQs

Questions 650–655

650. In athletes, physical fitness is more closely correlated with

Maximal oxygen uptake than with resting oxygen uptake.

Maximal pulse rate than with resting pulse rate.

Maximal minute ventilation than with maximal cardiac output.

Blood oxygen saturation than with blood lactate level during strenuous exercise.

Resting vagal tone than with resting sympathetic tone to the heart.

651. The muscle fibres adapted to endurance running

Are classiﬁed as slow rather than fast.

Have a relatively high myoglobin content.

Are red rather than white.

Have a relatively high mitochondria content.

Are classiﬁed as anaerobic rather than aerobic.

652. The oxygen consumed per minute

Is greater than the carbon dioxide produced per minute during long distance running.

In the resting adult is nearer 100 than 150 ml.

During intense mental activity can rise to twice the resting level.

During brisk walking is nearer ﬁve times than twice the resting level.

In an Olympic athlete can rise to 50 litres.

653. The increase in blood flow to muscle in an exercising limb is related to a

rise in

Local P

Local H

⫹

concentration.

Local muscle temperature.

Arterial pressure.

Vasodilator nerve activity.

654. During muscular training

Neural control factors improve performance before there is evidence of skeletal muscle
hypertrophy.

Repeated stretching of skeletal muscle ﬁbres leads to their hypertrophy.

There is a gradual decrease in the size of the heart in diastole.

There is a gradual increase in the O

extraction rate from blood perfusing exercising

skeletal muscle.

The increase in skeletal muscle blood flow for a given work load decreases.

655. Blood lactic acid is

Normally undetectable in resting subjects.

A product of anaerobic metabolism.

Increased by a 100-metre dash.

Not increased during steady state running in a marathon race.

Raised to about 5–10 moles/litre during maximal exercise.

MCQ

274

Sport and exercise physiology – answers

Answers

650.

True

Maximal oxygen uptake is the ‘gold standard’ of ﬁtness.

False

Maximal pulse rate is related to age; a slow pulse indicates ﬁtness.

False

Cardiac output is the usual limiting factor in exercise.

False

Saturation changes little during exercise; a relatively low lactate level during
strenuous exercise is an indication of ﬁtness.

True

A high resting vagal tone is the cause of the low resting heart rate.

651.

True

The time course of their twitch is relatively long.

True

This provides an intracellular store of oxygen.

True

This is due to their myoglobin content.

True

They generate energy by oxidative phosphorylation.

False

Their high rate of oxygen consumption classiﬁes them as aerobic.

652.

True

The respiratory quotient is less than 1.0 during long distance running.

False

It is around 250–300 ml.

False

Brain oxygen consumption increases in relatively small active areas, but the total
changes little.

True

This is a useful way of maintaining ﬁtness, particularly in older people.

False

The maximum recorded is less than ten litres.

653.

True

This causes local vasodilation.

True

Acidosis also favours vasodilation.

True

Heat dilates blood vessels.

False

Exercising a limb causes little change in mean arterial pressure.

False

Vasomotor nerves are not involved in exercise hyperaemia.

654.

True

Neural factors account for most of the early improvement in performance.

True

This is a potent factor causing hypertrophy.

False

There is an increase due to increased diastolic ﬁlling with the lower resting heart
rate.

True

This results in a lower blood lactate level for a given workload.

True

A consequence of the greater oxygen extraction rate.

655.

False

The resting level is around one millimole per litre.

True

It is a marker for anaerobic metabolism.

True

Almost all the energy used in the 100-metre dash comes from anaerobic metab-
olism.

False

Even though the lactic acid level is steady, it is still raised during steady state
exercise.

False

It rises to 5–10 millimoles per litre.

MCQ

Sport and exercise physiology – questions

275

Questions 656–661

656. Isotonic (dynamic) exercise differs from isometric (static) exercise in that

there is less

Increase in systolic arterial pressure.

Increase in diastolic arterial pressure.

Assistance to the circulation by the muscle pump.

Use of slow-twitch muscle ﬁbres.

Reliance on anaerobic glycolysis.

657. Electrocardiological danger signs during incremental treadmill exercise

include

A heart rate equal to the maximal predicted for the person’s age.

An R-R interval of about 500 milliseconds.

R waves with an amplitude greater than one millivolt.

Ventricular tachycardia.

ST depression of one millimetre.

658. Exercising in a hot chamber may induce

Fainting due to a decreased total peripheral resistance.

Heat stroke when core temperature rises above 40

A rise in alveolar P

A decrease in the osmolality of extracellular fluid.

Heat adaptation if performed daily for several weeks.

659. Cold

Injury to feet exposed for long periods to 5–10

C is due to frostbite.

Injury to the extremities is made less likely by increased afﬁnity of haemoglobin for O

at low temperatures.

Environments may induce a ﬁve-fold rise in resting metabolic rate.

Water immersion causes death from hypothermia more rapidly in fat than in thin
people.

Water immersion of the hand at 5

C is painless.

660. The maximum possible metabolic rate during exercise is

Reached when the blood lactate level starts to fall.

Reached when the respiratory exchange ratio starts to fall.

Reached when ventilation reaches the maximum breathing capacity.

Reduced by about half if the haemoglobin level falls by half.

About 50 times the resting rate in an athlete.

661. Asthma can interfere with exercise by

Increasing the work of breathing.

Cold-induced bronchial muscle spasm.

Limiting alveolar ventilation.

Reducing the diffusing capacity of the lung alveoli.

Reducing the oxygen carrying capacity of the blood.

MCQ

276

Sport and exercise physiology – answers

Answers

656.

False

There is a greater increase during isotonic exercise.

True

Diastolic pressure rises more with isometric exercise.

False

The muscle pump does not function during static exercise.

False

In dynamic exercise more use is made of endurance ﬁbres.

True

Isotonic exercise relies mainly on aerobic metabolism, whereas isometric exercise
relies mainly on anaerobic glycolysis.

657.

False

It is normal to reach one’s predicted maximal heart rate.

False

This implies a heart rate of about 120 beats/minute, well within the normal range.

False

This is also a normal ﬁnding.

True

Stroke volume is impaired and ventricular ﬁbrillation may develop.

False

Depression of 2–3 millimetres is the borderline level for danger.

658.

True

Vasodilation in skin in addition to that in muscle may reduce arterial pressure to
fainting point.

True

There is a serious risk of a progressive rise to fatal levels due to positive feedback.

False

It falls due to the hyperventilation induced by the rise in core temperature.

False

Osmolality rises due to the high output of hypotonic sweat.

True

By improving the efﬁciency of heat losing mechanisms, heat adaptation allows
the subject to have a smaller rise in core temperature for a given workload.

659.

False

The tissues do not freeze at this temperature; ‘trench foot’ injury can occur.

False

Hypoxia is an increased risk due to poor release of oxygen to the tissues.

True

Increased muscle tone and shivering account for this.

False

Fat people have much better insulation of their body core.

False

It is very painful, a warning of the danger of such temperatures.

660.

False

The lactate level keeps rising with increasing severity of exercise.

False

Increasing lactate acid increases ventilatory elimination of CO

; a rising respira-

tory exchange ratio suggests that exercise is approaching maximal.

False

The level of ventilation in exercise does not reach the maximum breathing capac-
ity.

True

Oxygen delivery depends crucially on the haemoglobin level.

False

The limit is about half of this.

661.

True

Due to the increased resistance of the airways.

True

Some people respond to increased ventilation of cold air in this way.

True

Ventilatory capacity falls as resistance increases.

False

The problem is in the bronchial tree, not the alveoli.

False

Asthma does not produce this effect.

MCQ

Sport and exercise physiology – questions

277

Questions 662–667

662. In someone with diabetes mellitus being treated by injected insulin

Omission of an insulin injection causes a rise in the blood glucose level.

Regular daily exercise increases insulin requirements.

Unaccustomed exercise leads to a low blood glucose level.

Carbohydrate intake should be decreased if daily exercise is increased.

Tremor may occur if the blood glucose level falls.

663. During maximal exercise, a 75 kg athlete aged 25 would have a

Heart rate nearer 200 than 150 beats/minute.

Stroke volume nearer 70 ml than 140 ml.

Tidal volume nearer 2 litres than 1 litre.

Blood lactate nearer 50 than 10 times the resting level.

Mixed venous blood oxygen content nearer 100 than 150 ml/litre.

664. Secondary amenorrhoea (disappearance of previously established men-

struation) in a 25-year-old female athlete is associated with

A strenuous daily training schedule.

Weight loss rather than weight gain.

Direct depression of the ovaries rather than loss of gonadotrophins and their releasing
hormone.

Reversal of the condition when strenuous exercise is discontinued and normal body
weight regained.

A body fat content of 25 per cent.

665. The metabolism of

Glycogen by exercising muscle leads to a respiratory quotient nearer 0.7 than 0.8.

Fat liberates more than twice the energy liberated by the same weight of carbohydrate.

Fatty acids by skeletal muscle plays no part in normal exercise.

Amino acids for energy is decreased by cortisol.

An 80 kg male athlete in training requires nearer 2000 kcal (8.4 MJ) than 3000 kcal
(12.6 MJ)/day.

666. Hypoxia in

Exercising muscle decreases the rate of lactate formation.

Life at high altitudes leads to a respiratory acidosis.

Patients with cardiac failure is of the hypoxic variety.

Patients with asthma is alleviated by treatment with adrenoceptor

␤ blocking drugs.

Smokers is due partly to carboxyhaemoglobin formation in blood.

667. During strenuous exercise (12 METS, where one MET is the resting meta-

bolic rate, corresponding to an oxygen consumption of 3.5 ml per
minute) as compared with moderate (6 METS) dynamic exercise, there is
a higher

Carbon dioxide production in the body.

Systolic arterial blood pressure.

Blood lactate level.

Arterial blood pH.

Respiratory exchange ratio.

MCQ

278

Sport and exercise physiology – answers

Answers

662.

True

There is impaired uptake and storage of glucose in muscle ﬁbres.

False

Exercise facilitates uptake of glucose in muscles and less insulin is needed.

True

The normal insulin dosage is now excessive.

False

Exercise increases carbohydrate requirements.

True

Tremor is part of the sympathetic response to the hypoglycaemia; included in this
response is a tendency to oppose the fall in blood glucose by mobilizing glucose
from hepatic glycogen.

663.

True

The predicted rate (220 minus age in years) is 195.

False

A heart rate of 195 and stroke volume of 70 would give a cardiac output of 13.65
litres/minute; maximal output in an athlete is about twice that value.

True

A tidal volume of 2 litres and respiratory rate of 60/minute gives a total ventila-
tion of 120 litres/minute.

False

It should be ﬁve to ten times the resting level.

True

It would be below 100 ml/litre (less than 50 per cent saturated); most of the cir-
culation passes through exercising muscles and gives up considerably more than
half its oxygen to the muscles.

664.

True

This is a recognized adverse effect of strenuous training over weeks or months.

True

Amenorrhoea is likely when body weight falls markedly below the normal value.

False

It is usually a hypothalamic response to a reduction in the body’s energy stores
which are sensed in the hypothalamus.

True

As at the menarche, reproductive activity, including ovulation and menstruation,
generally depend on attaining a normal adult body mass, including fat stores.

False

This is the normal female body fat level.

665.

False

The respiratory quotient for carbohydrate is 1.0.

True

The ratio is about 9:4.

False

Muscle energy is normally derived about equally from carbohydrate and fat.

False

Cortisol favours this catabolic process by converting amino acids into glucose.

False

Training greatly increases energy needs, up to 4000 kcal (16.8 MJ)/day, or more.

666.

False

Lack of oxygen leads to anaerobic glycolysis and increases lactic acid formation.

False

It stimulates ventilation and leads to a respiratory alkalosis.

False

It is ‘stagnant’ hypoxia due to inadequate tissue blood flow.

False

But beta-receptor stimulation leads to relaxation of airway smooth muscle and
should relieve hypoxia when caused by asthma.

True

Due to the carbon monoxide content of the smoke.

667.

True

Like O

consumption, CO

production is a precise index of metabolic rate.

True

Systolic pressure rises with the level of exercise as cardiac output increases.

True

With exercise at twelve times resting metabolic rate, the lactate level is high and
rising.

False

pH falls due to the lactic acid production.

True

This rises as the maximal level (10–15 METS for most people) is approached as
buffering of lactic acid leads to CO

production.

MCQ

Sport and exercise physiology – questions

279

Questions 668–673

668. The elastic recoil of muscles and tendons in the legs

Increases jumping height when someone jumps from a height immediately before take
off.

Improves performance during sprinting.

Contributes more to performance when sprinting on a cinder track than on a concrete
surface.

Can be improved by training.

Is greater in weight lifters than in skiers.

669. The risk of osteoporosis is increased

In people between 60 and 90 years of age as compared with people between 40 and 50
years of age.

In males as compared with females.

During prolonged periods of bedrest.

When both ovaries are removed in a premenopausal woman.

During treatment with adrenal glucocorticoids.

670. During a hospital treadmill exercise test, cardiac abnormality is suggested

A heart rate greater than 150 beats per minute.

A systolic arterial pressure greater than 150 mmHg.

ST depression greater than 5 mm in the ECG.

Inability to follow the usual protocol because of discomfort in the legs.

A falling systolic arterial pressure during the test.

671. For the average healthy, normal male aged 20, the

Body fat is about 30 per cent of total body weight.

Skin-fold thickness is higher than in a female.

Heart rate during maximal exertion is about 200 beats per minute.

Cardiac output during maximal exertion is about 10 litres per minute.

Maximal oxygen consumption is about 10 ml/kg/minute.

672. Heat

Load during maximal exertion should not exceed three times resting heat load.

Syncope is caused by an inappropriately high cardiac output.

Stroke is a less serious condition than heat syncope.

Adaptation results in the subject having a smaller rise in core temperature for a given
level of work.

Adaptation takes about six days rather than six weeks to develop.

673. Pain is produced by

Potassium ions more than by sodium ions.

Occluding the circulation to an exercising limb for ﬁve minutes.

Occluding the circulation to a resting limb for ﬁve minutes.

Raised tissue endorphin levels.

Thawing of tissue frozen during frostbite.

MCQ

280

Sport and exercise physiology – answers

Answers

668.

True

The elastic tissue in extensor muscles is stretched by the initial downward jump.

True

Elastic recoil aids the activity independently of muscular contractions.

False

The concrete surface ‘reflects’ more of the energy stored during landing the foot
on the surface.

True

Training which stretches the muscles achieves this.

False

Compared with skiers, weight lifters produce little muscle stretch and rebound
during training.

669.

True

Bone density declines, particularly after 60.

False

The risk is considerably greater in females, especially after the menopause.

True

Normal calciﬁcation requires exposure of the bone to gravitational and other
stress.

True

This leads to an artiﬁcial menopause and a considerably increased risk.

True

These lead to breakdown of bone collagen thereby reducing bone strength.

670.

False

This would be the predicted normal for someone of 70 years of age.

False

Systolic pressure rises to 200 mmHg in ﬁt young people.

True

This level indicates severely inadequate blood flow (ischaemia) – the threshold for
deﬁnite abnormality is around 3 mm (0.3 mV) depression.

False

The abnormality (inadequate flow, muscle fatigue etc.) is in the legs.

True

This means the heart is failing to pump adequately and is a serious sign.

671.

False

The normal is around 15 per cent.

False

Females normally have greater deposits of fat in the skin.

True

This is the predicted value (220 minus age in years).

False

It is around 20–25 litres/minute.

False

Average values are around 30–40 ml/kg/minute.

672.

False

It normally increases ten to ﬁfteen-fold in a ﬁt individual.

False

It is caused by cardiac output not rising sufﬁciently to compensate for the fall in
peripheral resistance due to the skin vasodilation.

False

Unlike heat syncope, heat stroke is likely to be fatal unless treated promptly and
effectively.

True

Due to the development of more efﬁcient heat-losing mechanisms.

False

Six weeks gives useful and fairly complete adaptation.

673.

True

Injections of isotonic potassium but not sodium into the skin are extremely pain-
ful.

True

Due to the accumulation of pain-producing metabolites when blood flow is in-
adequate to clear the metabolites generated by muscle exercise.

False

Accumulation of such metabolites is very slow in the resting limb; with more pro-
longed occlusion, anaesthesia due to nerve hypoxia usually occurs before
metabolite retention in the tissues rises to the levels needed to stimulate pain
nerve endings.

False

Endorphins inhibit pain pathways.

True

Thawing releases pain mediators and restores function to numbed nerves.

MCQ

Sport and exercise physiology – questions

281

Questions 674–679

674. Heart disease may limit exercise tolerance by

Reducing the patient’s maximal cardiac output.

Increasing the left ventricular ejection fraction.

Depriving cardiac muscle of an adequate blood supply.

Decreasing heart rate through increased vagal tone.

Changing the relationship between cardiac work and ﬁbre length.

675. Respiratory disease can limit exercise by halving the

Vital capacity.

Airway conductance.

Body’s resting oxygen consumption.

Oxygen-carrying capacity of the blood.

Rate of pulmonary blood flow.

676. Olympic level endurance fitness is associated with an exceptionally high

Haemoglobin level.

Oxygen saturation of the blood.

Vital capacity.

Cardiac vagal tone during maximal exercise.

Resting stroke volume.

677. Exercise at high altitudes is hindered by

Increased resistance by the atmosphere to athletic activity.

A fall in the total oxygen supply available to muscle during maximal effort.

Respiratory alkalosis.

The compensatory fall in blood bicarbonate level.

High blood lactate levels during severe exertion.

678. Malnutrition can limit exercise tolerance by

Reducing muscle bulk and hence strength.

Depleting stores of glycogen and fat.

Causing hypoxic rather than anaemic hypoxia.

Causing iron deﬁciency.

Depleting energy stores even though daily food energy intake exceeds 2500 kcal
(10.5 MJ).

679. Increased arousal during competitive sport is indicated by

Dilation of the pupils.

A high resting heart rate.

Increased muscle blood flow.

Decreased sweating.

Tremor.

MCQ

282

Sport and exercise physiology – answers

Answers

674.

True

This is the main mechanism limiting exercise.

False

It decreases ejection fraction and hence stroke volume and cardiac output.

True

This causes temporary (angina) and potentially permanent (myocardial infarc-
tion) dysfunction.

False

It may decrease heart rate by blocking impulses from the sinoatrial node to the
ventricles.

True

It decreases work done at a given ﬁbre length on the left ventricular function
curve.

675.

True

This may occur in severe obstructive or restrictive disease.

True

This may occur in obstructive disease such as asthma.

False

Unless resting oxygen requirements are met, death results immediately.

False

The oxygen carrying capacity of blood often rises in respiratory disease because
of polycythaemia; desaturation of haemoglobin is the usual cause of hypoxia in
respiratory disease.

False

Pulmonary blood flow equals cardiac output, which tends to rise in respiratory
disease.

676.

False

Not unless the individual has been training at high altitude; for some activities a
maximal haematocrit is set to discourage artiﬁcial means of raising the oxygen
carrying ability of blood.

False

This also is likely to be normal (around 98 per cent in arterial blood).

False

Ventilation is not usually a limiting factor for endurance activity.

False

There will only be sympathetic tone to the heart at maximal exercise.

True

This permits a low resting pulse rate and a high maximal cardiac output.

677.

False

Atmospheric drag is reduced at high altitudes.

True

Due to impaired saturation of the blood with oxygen (hypoxic hypoxia).

True

Due to increased ventilation induced by hypoxia; this limits ability to further
increase ventilation.

False

This compensates for the low P

and allows increased ventilation.

True

Lactate levels tend to rise rapidly and fall slowly, leading to intense fatigue and
collapse.

678.

True

Due to shortage of amino acids to repair loss due to normal turnover.

True

Thus the substrates for energy production in exercise are missing.

False

A reduced haemoglobin level is common and causes anaemic hypoxia.

True

This is the commonest cause of anaemia (haemoglobin contains iron).

True

High activity requires more energy than this so there would be negative energy
balance.

679.

True

Due to stimulation of radial dilator ﬁbres by sympathetic nerves.

True

Another sympathetic effect.

True

Due partly to circulating adrenaline.

False

Sweating increases as part of the ﬁght or flight response.

True

Another beta sympathetic adrenoceptor response.

MCQ

Sport and exercise physiology – questions

283

Questions 680–684

680. In someone whose activities are limited by a recent stroke

Weakness is more of muscular than neurological origin.

Voluntary movements are better preserved than reflex movements such as the knee jerk.

Speech difﬁculties are usually worse when the weakness is left-sided.

Weakness usually affects both legs.

The main area of nervous system damage is usually in the cerebellum.

681. Exercise at a level of 10 METS

Implies a rate of energy consumption ten times that of the basal metabolic rate.

Requires an oxygen uptake of 2 to 3 litres per minute in the average adult.

Requires an oxygen uptake of less than 2 litres per minute in a 20 kg child.

Is not suitable for a person on insulin treatment for diabetes mellitus.

Is probably too much for a ﬁt 90-year-old person to maintain for one hour.

682. An environmental temperature of 40°C

Is thermoneutral if there is a strong wind.

Leads to a generalized release of sympathetic vasoconstrictor tone.

Leads to an increase in heat loss by convection and radiation from the skin.

May lead to heat stroke if relative humidity is 100 per cent.

Is appropriate for people in training for heat adaptation in a climatic chamber.

683. A feeling of anxiety before a sporting event may be associated with an

increase in

Heart rate.

Parasympathetic activity.

Beta adrenoceptor blockade.

Circulating levels of adrenaline.

Resting respiratory rate.

684. An appropriate daily dietary energy intake for a 70 kg adult

Who is sedentary and wishes to lose weight is nearer 1500 than 3000 kcal (6.3 versus
12.6 MJ).

Convalescing from a wasting illness would be nearer 3000 than 2000 kcal (12.6 versus
8.4 MJ).

In training averaging 10 METS for 6 hours/day is more than twice that required for sed-
entary conditions.

Athlete should be sufﬁcient to avoid ketoacidosis.

Should contain as little carbohydrate as possible.

MCQ

284

Sport and exercise physiology – answers

Answers

680.

False

The weakness is of neurological origin.

False

Voluntary movements are weak, but spinal reflexes such as the knee jerk are usu-
ally increased.

False

The muscles on the right side and speech are usually controlled by the left side
of the brain; both are usually impaired when the left side of the brain is damaged
by a stroke.

False

A stroke usually affects just one side of the body.

False

The damage is usually in one cerebral hemisphere, where the main motor ﬁbres
pass from the cerebral cortex to the brainstem.

681.

False

Conventionally it is ten times the resting rate (higher than the basal rate).

True

10 METS require 10 times the resting oxygen consumption of around
250 ml/minute.

True

Resting metabolic rate is roughly proportional to body mass.

False

Such people should exercise at this level, but advice is needed on dietary and
insulin needs.

True

The world record for the mile at this age is between ten and ﬁfteen minutes,
implying much less than ten METS for about a quarter of an hour.

682.

False

The maximal thermoneutral temperature is around 30 degrees.

False

Thermoregulatory release of vasoconstrictor tone is conﬁned to skin blood ves-
sels.

False

Since the ambient temperature is higher than blood temperature, the only ave-
nues left for heat loss are evaporation of sweat and fluid lining the respiratory
tract.

True

Exercise in such environments is inadvisable.

True

Provided the relative humidity is low.

683.

True

An increased heart rate is a feature of increased sympathetic drive.

False

This tends to produce a relaxed, drowsy state as after a large meal.

False

Beta blocking drugs reduce the tachycardia and tremor which exacerbate anxiety.

True

This produces tachycardia and tremor.

True

This is another physical correlate of anxiety.

684.

True

This gives a daily deﬁcit of about 500 kcal which would be supplied by metabo-
lizing fat stores.

True

This provides a positive energy balance and allows replenishment of body pro-
tein and fat, assuming an adequate protein content of the diet.

True

Metabolizing at 10 METS for 6 hours (60 MET hours) would itself use up more
than the daily sedentary requirement (e.g. sleeping for 8 hours, about 8 MET
hours; average 2 METS for 16 hours, 32 MET hours).

True

Ketoacidosis impairs muscle function.

False

A moderate carbohydrate intake is required to avoid ketoacidosis; a relatively
high carbohydrate intake is required for exercise.

MCQ

Sport and exercise physiology – questions

285

Questions 685–686

685. The increase in ventilation during maximal exercise

May exceed 100 litres/minute in a young 70 kg adult.

Is smaller when the exercise is performed at high altitudes.

Is related in part to a fall in pH due to lactic acidosis.

Is related in part to stimulation of receptors in muscle (‘metaboreceptors’) by metabolic
products of exercise.

Does not involve the brain above the level of the brain stem (pons, midbrain and
medulla).

686. Glycogen stores in skeletal muscle

Are beyond the resolution of the electron microscope.

Help the body to avoid ketoacidosis during exercise.

Increase during endurance training.

Are replaced more completely if carbohydrate is ingested immediately, rather than
hours, after exercise.

Are depleted in people with inadequately treated diabetes mellitus.

MCQ

286

Sport and exercise physiology – answers

Answers

685.

True

This is necessary to maintain a normal alveolar oxygen level and full blood
oxygen saturation.

False

It is increased due to the low oxygen content at low atmospheric pressures; ven-
tilatory ability can then be a limiting factor.

True

This occurs above the anaerobic/lactate threshold.

True

Ventilation is somewhat reduced if this input to the brain is blocked.

False

The precise matching of ventilation to exercise requirements is postulated to take
place in an ‘exercise centre’ which receives an input from the cortical neurones
initiating the exercise.

686.

False

Glycogen granules are readily identiﬁable in sections of biopsied muscle.

True

By providing an adequate source of glucose.

True

This is an important effect of training; muscle glycogen stores may then exceed
1 kg.

True

This has been conﬁrmed in studies involving muscle biopsies.

True

Insulin promotes glucose uptake by muscle for replenishment of glycogen stores.

MCQ

SPORT AND EXERCISE PHYSIOLOGY

287

EMQs

Questions 687–691

EMQ Question 687

For each measurement of physical ﬁtness A–E, select the most appropriate option from the fol-
lowing list of physiological terms.

1. Aerobic metabolism.

2. Anaerobic metabolism.

3. Slow twitch muscle.

4. Fast twitch muscle.

5. Maximal oxygen consumption.

6. Respiratory quotient.

The subject tested measures handgrip strength by gripping as strongly as possible a
measuring device which gives a reading proportional to the strength of the handgrip.

The subject runs back and forward across a 20 metre length in time to a series of beeps,
one for each traverse; the beeps gradually come closer together and the subject’s score
is the number of twenty laps completed before giving up either due to fatigue or lag-
ging behind the beeps.

Small samples of blood are taken from an athlete’s ear lobe during exercise and meas-
ured for lactic acid content.

The subject’s ventilation rate (litres per minute) expired carbon dioxide and oxygen
levels, heart rate, respiratory exchange ratio and blood lactic acid level are measured
each 15 seconds during exercise at an increasing level, reaching exhaustion after about
15 minutes.

The timing for completion of a Marathon is recorded.

EMQ Question 688

For each description of an aspect of running the Marathon A–E, select the most appropriate
option from the following list of physiological mechanisms.

1. Brainstem respiratory control.

2. Higher centre respiratory control.

3. Local metabolic control of vascular

4 Baroreceptor reflex control of vascular tone.

tone.

5. Low level sympathetic activity.

6. High level sympathetic activity.

7. Low vagal tone.

8. High vagal tone.

As the run proceeds in medium temperature conditions, the runner’s skin becomes
markedly flushed.

Despite differing levels of exertion, the runners maintain their arterial oxygen pressures
close to their normal resting values.

As the race proceeds the runners show marked sweating and take in fluid to maintain
fluid balance.

The runners have very high levels of blood flow through their leg muscles.

A positive correlation has been found between a runner’s resting heart rate and time
taken to complete the Marathon.

EMQ

288

Sport and exercise physiology – answers

Answers for 687

Option 4

Fast twitch muscle. This is a test of muscle strength as opposed to endu-

rance; it is related to muscle bulk and not skill, so the dominant hand is not always the
strongest.

Option 3

Slow twitch muscle. In contrast to the above, this is a test of endurance, a

property of the less bulky slow twitch muscles.

Option 2

Anaerobic metabolism. Lactic acid is a marker for anaerobic metabolism; a

relatively low value at a high level of performance indicates good ﬁtness.

Option 5

Maximal oxygen consumption. Oxygen consumption is calculated from the

difference between inspired (atmospheric) and expired oxygen multiplied by the ventila-
tion rate; it is assumed to be maximal when a plateau is reached around the time of
exhaustion; heart rate should be maximal and the respiratory exchange ratio (carbon
dioxide output/oxygen uptake) should have risen to above 1.0; lactic acid is usually 5–10
times the resting value.

Option 3

Slow twitch muscle. For most people this is the ultimate test of the slow

twitch endurance muscle.

Answers for 688

Option 5

Low level sympathetic activity. As the runners generate increased heat from

their exercising muscles there is temperature reflex release of sympathetic tone to the skin
blood vessels; removal of the resting constrictor tone causes vasodilation.

Option 2

Higher centre respiratory control. The precise matching of ventilation (and

cardiac output) to muscular activity is evidence of sophisticated cerebral activity above
the level of the automatic, reflex centres in the medulla; this concept has led to the term,
‘exercise centre’.

Option 6

High level sympathetic activity. Sweating is induced by activity in choliner-

gic sympathetic nerves to sweat glands.

Option 3

Local metabolic control of vascular tone. The huge increase in muscle blood

flow is due to metabolic changes generated locally by the active muscles.

Option 8

High vagal tone. Endurance athletes, such as marathon runners, demonstrate

their ﬁtness by having very low (e.g. 30–40 beats per minute) heart rates due to very high
resting cardiac vagal tone; this is related to their having large powerful hearts with a high
stroke volume so resting cardiac output requires only a low heart rate; during exercise
they can reach the usual high rates, so multiplying their resting cardiac output during
maximal exercise much more (say 6 times) than the average person (say 3–4 times).

EMQ

Sport and exercise physiology – questions

289

EMQ Question 689

For each aspect of physical exertion in people with insulin-dependent diabetes mellitus A–E,
select the most appropriate option from the following list of physiological terms.

1. Decreased insulin requirement.

2. Increased insulin requirement.

3. Hyperglycaemia.

4. Hypoglycaemia.

5. Parasympathetic effects.

6. Sympathetic effects.

Prior to a two-hour period of strenuous physical afternoon’s activity, diabetic patients
require to increase their nutritional intake and adjust their dose of insulin compared
with that taken before a sedentary afternoon.

A major risk for such people is that they will develop a period of confusion during
strenuous activity or during the following evening or night.

During such a period of confusion, the patient often shows pallor and sweating.

Prior to a period of strenuous activity it is reassuring rather than alarming to ﬁnd the
blood glucose around the renal threshold for glycosuria.

After a full day of strenuous activity, the person with diabetes may set the alarm several
times during the night so as to be able to test the blood glucose level.

EMQ Question 690

For each description of skeletal muscle activity A–E, select the most appropriate option from
the following list of contrasting muscle attributes.

1. Energy produced in mitochondria.

2. Energy produced outside mitochondria.

3. Low level of myoglobin.

4. High level of myoglobin.

5. Low density of capillaries.

6. High density of capillaries.

Adaptation to aerobic activity is associated with increased ability to store oxygen intra-
cellularly.

Adaptation to anaerobic activity is associated with a low rate of oxygen uptake by the
cell.

Anaerobic activity is associated with a high rate of breakdown of glucose.

Typical massively muscular strong individuals can lift huge weights but rapidly flag
when trying to run.

Rapid twitch muscle is typically pale in comparison with slow endurance muscle.

EMQ Question 691

For each description of muscular activity A–E, select the most appropriate level of METS from
the following list, where 1 MET equals the rate of metabolism associated with each individual
in the stable resting state (3.5 ml oxygen/min/kg weight).

1. 0.5 METS.

2. 1 MET.

3. 2 METS.

4. 4 METS.

5. 8 METS.

6. 16 METS.

7. 32 METS.

8. 64 METS.

An individual with cardiac or respiratory disease is just able to leave the house and
walk slowly for a short distance.

An individual who is above average physical ﬁtness and is being considered for a
national athletics team can just reach this level.

The level of activity associated with brisk walking.

The level of activity associated with the average individual climbing 100–200 steps at a
rate which is approaching the maximal possible for that person.

The level of sustainable activity in a ﬁt 90-year-old.

EMQ

290

Sport and exercise physiology – answers

Answers for 689

Option 1

Decreased insulin requirement. Prolonged strenuous exercise requires

increased nutritional intake; with exercise, the insulin requirement for nutritional uptake
into cells is much reduced.

Option 4

Hypoglycaemia. As nutrients are depleted during exercise, even a reduced

dose of insulin may lower the blood glucose level below that which will sustain normal
cerebral activity; a falling glucose level causes progressively, confusion, coma and risk of
brain damage and death.

Option 6

Sympathetic effects. These effects give a useful clue to the diagnosis; sym-

pathetic stimulation leads to skin vasoconstriction and sweating, also tremor and tachy-
cardia; hypoglycaemia also activates the gastric vagus to increase secretion and activity,
possibly inducing hunger and facilitating rapid transit of a remedial high-energy snack.

Option 3

Hyperglycaemia. The renal threshold is about twice the normal fasting level;

such transient hyperglycaemia is of little consequence compared with the risks of trying
to keep the blood glucose normal and thereby risking the vastly greater danger of hypo-
glycaemia.

Option 4

Hypoglycaemia. The blood glucose can dip severely some hours after pro-

longed exertion; nocturnal hypoglycaemia is particularly pernicious as the person may
lapse into coma during sleep; it is much better to disturb sleep and conﬁrm a threatening
fall in blood glucose before it progresses to interfere with consciousness.

Answers for 690

Option 4

High level of myoglobin. Myoglobin is the muscular intracellular form of

haemoglobin; aerobic endurance muscle has high levels for oxygen storage to maintain a
smooth flow of oxygen to the mitochondria.

Option 5

Low density of capillaries. Capillary density determines the rate of oxygen

uptake and is low in powerful fast-twitch anaerobic muscles.

Option 2

Energy produced outside mitochondria. Anaerobic activity derives energy

from glycolysis outside the mitochondria; since this produces high energy phosphate at a
low rate per molecule of glucose, much glucose must be broken down.

Option 2

Energy produced outside mitochondria. These people major in fast twitch

muscle which can produce huge amounts of energy for a matter of seconds, but their
muscle is poor in mitochondria, which alone can sustain steady energy production for
endurance activities.

Option 3

Low level of myoglobin. Rapid twitch muscle lacks the pigment myoglobin.

Answers for 691

Option 3

2 METS. This is the borderline between being able to get out and about and

being totally housebound and 100 per cent disabled.

Option 6

16 METS. The average ﬁt young to middle-aged person can reach around

10 METS; athletes around 15–20 METS; super Olympic athletes may exceed this.

Option 4

4 METS. Brisk walking involves almost half way to maximal exertion for

many people.

Option 5

8 METS. Since the average person can reach about 10 METS, 8 METS is

close to the maximal sustainable for a moderate period of time.

Option 4

4 METS. Maximal exertional ability declines after around 25–30 years; the

world record for the mile at 90 years of age is just under a quarter of an hour, not much
above the brisk walking speed.

EMQ

INTERPRETIVE QUESTIONS

291

MCQs

Questions 692–708

MCQ Question 692

Figure 12.1 shows two blood oxygen dissociation curves. ‘A’ represents the oxygen partial pres-
sure in normal alveoli, ‘H’ the lowered alveolar oxygen pressure in hypoxic lungs due to high
altitude or pulmonary disease and ‘V’ the mixed systemic venous oxygen pressure in the person
suffering from hypoxia. In this diagram:
a.

If (i) is a normal person’s curve, then (ii) is the hypoxic person’s curve, rather than vice
versa.

The blood in curve (i) has a higher red cell level of 2,3-diphosphoglycerate (2,3-DPG).

The O

saturation of blood leaving the hypoxic lungs is lower with curve (ii) than with

curve (i).

The oxygen extracted by the tissues equals oxygen uptake in the lungs for both curves
in both people, other things being equal.

The curve labelled (i) is more suitable for fetal conditions than the curve labelled (ii).

MCQ

100%

(i)

(ii)

Oxygen partial pressure

Blood o

xygen satur

ation

Figure 12.1

292

Interpretive questions – answers

Answers to 692

True

The hypoxic person’s curve is displaced to the right.

False

2,3-DPG shifts the curve to the right.

True

This is apparent from the graph and is a disadvantage of the increased 2,3-DPG;
notice that at this point the curve is shifted downwards as well as to the right.

True

Neither normal people nor hypoxic people can run up an oxygen debt at rest, so
in both cases pulmonary uptake must balance tissue delivery; in the case of the
hypoxic person, pulmonary uptake corresponds to XY which equals YZ which
corresponds to tissue delivery.

True

Fetal blood is shifted even further to the left and is able to take up O

at the low

levels found in the maternal sinusoids.

MCQ

Interpretive questions – questions

293

MCQ Question 693

Figure 12.2 indicates some events during two respiratory cycles, where I

⫽inspiration and

⫽expiration. In the second cycle, tidal volume was three times that in the ﬁrst cycle.

Expiration was not forced. It can be concluded that:
a.

Record A shows the changes in intrapleural pressure.

Record B shows the changes in intrapulmonary pressure.

Record C shows the rate of gas flow into and out of the lungs.

The compliance of the lungs and chest wall is increased markedly in the second cycle.

Maximum airflow occurs at the end of inspiration.

MCQ

I E I E

Figure 12.2

294

Interpretive questions – answers

Answers for 693

True

Intrapleural pressure is negative throughout the cycle and is minimum at the end
of inspiration; it becomes more negative with a deeper inspiration.

True

Intrapulmonary pressure (that is intra-alveolar pressure) reaches its minimum
around mid-inspiration and its maximum around mid-expiration.

False

The flow record closely follows the intrapulmonary pressure record B since flow
is directly related to pressure gradient between alveoli and atmosphere; record C
shows changes in lung volume.

False

Compliance, the volume change for a given pressure change, is similar in both;
though the pressure gradient is increased about three times in the second cycle,
so is the tidal volume.

False

Airflow is zero at end inspiration; it is maximum in mid-inspiration and mid-
expiration.

MCQ

Interpretive questions – questions

295

MCQ Question 694

In the acid–base diagram shown in Figure 12.3, where ‘L’ and ‘U’ represent the lower and upper
levels of normal respectively, a patient whose arterial blood values were found to be at point:
a.

V might have a compensated metabolic alkalosis.

W might have an uncompensated respiratory alkalosis.

X might have a compensated metabolic alkalosis.

Y might have a partly compensated respiratory acidosis.

Z might be suffering from severe vomiting.

MCQ

Log P

HCO

–

HCO

–

Figure 12.3

296

Interpretive questions – answers

Answers for 694

False

Since all parameters are within normal range, acid–base balance is normal; for a
metabolic alkalosis (compensated or uncompensated) the bicarbonate level must
be above normal.

True

The rise in pH is associated with a low P

but a normal HCO

⫺

True

Or a compensated respiratory acidosis; in both cases bicarbonate and carbon
dioxide levels are raised proportionately, so that the ratio P

to HCO

⫺

is normal,

giving a normal pH.

False

The patient has a partly compensated metabolic acidosis (low bicarbonate); the
low pH indicates incomplete compensation; for a respiratory acidosis the carbon
dioxide level must be above normal.

True

The patient has an uncompensated metabolic alkalosis caused by severe loss of
gastric acid.

MCQ

Interpretive questions – questions

297

MCQ Question 695

Figure 12.4 shows simultaneous records of changes in right hand and left forearm volume
when collecting pressures are applied intermittently by means of cuffs on the right wrist and
left upper arm respectively. The volume of the hand in the plethysmograph was 300 ml and the
volume of the forearm was 600 ml. These records (venous occlusion plethysmograms) show:
a.

A greater hand blood flow in the third than in the fourth plethysmogram.

That the rate of blood flow per unit volume of tissue is similar in the hand and forearm.

That hand blood flow is more variable than forearm blood flow.

That forearm blood flow is nearer 20 than 50 ml/minute.

That the collecting cuffs are not occluding the arteries.

MCQ

10 ml

Right hand

Left forearm

Minutes

Figure 12.4

298

Interpretive questions – answers

Answers for 695

False

Flow is measured as increase in volume with time and hence is directly propor-
tional to the slope of the volume record during collection.

False

The total blood flow rates are similar on the two sides; since hand volume is half
that of the forearm, its rate of flow per unit volume of tissue is approximately
double forearm flow.

True

The slopes are more variable; the more variable flow is due to greater variability
in the level of sympathetic vasoconstrictor tone.

False

The rate of flow is quite close to 50 ml/minute.

True

If the arteries were occluded, flow would be zero.

MCQ

Interpretive questions – questions

299

MCQ Question 696

Results are given in the table below of a person’s vital capacity (VC), forced expiratory volume
in one second (FEV

1.0

) and peak flow rate (PFR). The subject of these tests:

Is more likely to be a man of 25 than a woman of 65.

Is more likely to be suffering from restrictive lung disease than obstructive airways dis-
ease.

May have asthma, chronic bronchitis or emphysema.

Typically will have an arterial P

50 per cent above normal.

May have a compensated respiratory acidosis.

Observed (O)

Predicted (P)

O/P

4.0

5.3 litres

76%

FEV

1.0

2.0

4.4 litres

45%

FEV

1.0

/VC%

50%

83%

56%

PFR

200

645 litres/minute

31%

MCQ

300

Interpretive questions – answers

Answers for 696

True

The predicted values are those of a man of 25 (height 70”, 1.8 m); for a woman
of 65 (63”, 1.6 m), the FEV

1.0

of 2.0 litres would be normal.

False

The relatively severe reduction in FEV

1.0

and PFR are typical of severe obstruc-

tive disease; in restrictive disease, FEV

1.0

and VC are reduced to a similar extent.

True

All of these produce a similar ‘obstructive’ pattern of respiratory function.

False

Respiratory failure is a rare complication of obstructive airways disease.

True

If the condition leads to some carbon dioxide retention. Note: ‘typically’ implies
a majority of cases; ‘may’ implies a possibility, which could be a small minority
of cases.

MCQ

Interpretive questions – questions

301

MCQ Question 697

Figure 12.5 shows left ventricular (LV) function curves of the Frank–Starling type. If point X
on curve B represents the conditions in the normal heart at rest then point:
a.

Z might represent conditions in the failing ventricle at rest.

Y might represent resting conditions in the ventricle in hypertension prior to failure.

Y, rather than point V, might represent conditions in the ventricle after administration
of a beta adrenoceptor agonist drug.

V might represent conditions in a patient with aortic valve stenosis prior to failure.

W might represent the conditions in hypovolaemic circulatory failure.

MCQ

LV End-diastolic pressure

Stro

Figure 12.5

302

Interpretive questions – answers

Answers for 697

True

Stroke work is subnormal; end-diastolic pressure increased.

False

In early hypertension the left ventricle hypertrophies; stroke work is greater than
normal at a given ﬁlling pressure (point V on curve A).

False

Such a drug, e.g. isoproterenol (isoprenaline), mimics sympathetic stimulation
and moves the ventricular curve upwards and to the left (to a point below V on
curve A).

True

Stroke work is considerably increased, end-diastolic pressure little changed.

True

Ventricular function is normal but ﬁlling of the heart is inadequate.

MCQ

Interpretive questions – questions

303

MCQ Questions 698

In Figure 12.6 showing blood carbon dioxide dissociation curves:
a.

A fall in blood P

would shift the curve from A to B.

If point X represents the situation at the venous end of systemic capillaries, then point
Y represents the situation of the same blood at the venous end of the pulmonary capil-
laries.

A rise in blood P

would shift the curve from B to A.

The decrease in the slope of the curves as P

rises is related to the saturation of

plasma with CO

as P

rises.

At a P

of 50 mmHg, the amount of CO

in solution is lower in curve B than in curve

MCQ

100 mmHg
13.3 kPa

Blood CO concentr

ation mm

/100 ml

Figure 12.6

304

Interpretive questions – answers

Answers for 698

False

The reverse is true; deoxygenated blood can carry more CO

than oxygenated

blood at a given carbon dioxide pressure.

True

In the lungs the blood oxygen saturation rises shifting the curve from A to B and
the CO

content and pressure fall from point X to point Y.

False

It would merely shift the position on a given dissociation curve.

False

Plasma does not become saturated with CO

; CO

content remains proportional to

; the initial sharp rise is due to formation of carbamino compounds – this falls

off sharply as the number of free amino groups declines.

False

The amount of CO

in solution is the same for both curves for any P

; differ-

ences in total CO

content are due to differences in bicarbonate and carbamino

content; at low oxygen pressures, the desaturated haemoglobin is increasingly
more effective in buffering hydrogen ions and, by the law of mass action, favours
formation of bicarbonate ions from carbon dioxide.

MCQ

Interpretive questions – questions

305

MCQ Questions 699

In Figure 12.7, the line VXYW represents the threshold of hearing at various frequencies for a
normal subject. The:
a.

Sound waves with the characteristics represented by point Z are audible to the subject.

Interval AB on the ordinate represents 2.0 rather than 20 decibels.

Point D on the abscissa corresponds to 5000 rather than 1000 Hz.

Segment XY includes the frequencies most important in the auditory perception of
speech.

Curve is shifted downwards in the presence of background noise.

MCQ

Sound energy

100

10 000 Hz

Figure 12.7

306

Interpretive questions – answers

Answers for 699

False

Anything below the line is inaudible, having less energy than the threshold value
for detection at a particular frequency (Hz).

False

AB and BC both represent 20 decibels; thus sounds at the extremes of the hear-
ing range need relatively high energy to be heard.

False

It corresponds to 1000 Hz; the frequency (or pitch) scale is logarithmic.

True

The ear is most sensitive to sounds in the range 1000–3000 Hz (XY), which
includes the frequencies most important in distinguishing the different words in
speech.

False

It is shifted upwards since extraneous (masking) noise raises auditory threshold,
that is the lowest energy level at which a sound of a particular frequency can just
be detected.

MCQ

Interpretive questions – questions

307

MCQ Question 700

In Figure 12.8, which illustrates the handling of glucose by the kidney:
a.

Line A represents the rate of glucose ﬁltration by the glomeruli.

Line B could represent the rate of absorption of glucose by the proximal convoluted
tubules.

Line C follows curve DE rather than angle DFE because different nephrons have differ-
ent thresholds.

H indicates the maximal reabsorbing capacity of the kidney for glucose.

Renal poisons such as phlorhizin lower the value of H and shift line B to the right.

MCQ

Glucose mass/min

Plasma glucose concentration

Figure 12.8

308

Interpretive questions – answers

Answers for 700

True

The rate of ﬁltration is directly proportional to the plasma concentration.

False

Line B represents the rate of excretion of glucose; line C represents glucose reab-
sorbed; at low glucose concentrations absorption increases with the concentra-
tion and is complete; above these levels, EC, the maximal amount of glucose is
absorbed and the rest excreted.

True

Notice that glucose excretion gradually builds up at the same time due to loss of
glucose by the less effective nephrons.

True

The diagram shows features which are typical of a transport system with a lim-
ited maximal reabsorbing capacity.

False

Though H is lowered, the reduction of T

(glucose) results in glucose excretion at

lower plasma glucose levels so the line B shifts to the left.

MCQ

Interpretive questions – questions

309

MCQ Question 701

In a patient with a red cell count (RCC) of 4

⫻10

/litre, a haemoglobin (Hb) of 7.5 g/100 ml

and a haematocrit of 0.28:
a.

The mean corpuscular haemoglobin (MCH) is nearer 20 picograms (pg) than 20 nano-
grams (ng). 1pg

⫽10

⫺12

g; 1 ng

⫽10

⫺9

The mean cell volume (MCV) is nearer 95 than 70 fl (1 femtolitre

⫽1 ␮m

The mean corpuscular haemoglobin concentration (MCHC) is nearer 30 than
35 g/100 ml.

The cause of the anaemia is most likely to be vitamin B

deﬁciency.

The patient requires a blood transfusion.

MCQ

310

Interpretive questions – answers

Answers for 701

True

Hb/litre

75g

MCH

⫽

⫽18.75⫻10

⫺12

⫽18.75 pg

RCC/litre 4

⫻10

This is below normal (27–32 pg).
b.

False

Red cell volume/litre

0.28

MCV

⫽

litres

⫽70 fl.

Red cell count/litre

⫻10

Since the normal volume is about 75–95 fl, these cells are microcytic.
c.

True

7.5

MCHC

⫽

⫽26.8 g/100 ml

Haematocrit

0.28

Since the normal MCHV is about 30–35 g/100 ml, these cells are hypochromic.
d.

False

This microcytic, hypochromic picture is characteristic of iron deﬁciency.

False

Moderate iron deﬁciency anaemia of this sort responds well to iron therapy:
blood transfusions should not be used unless absolutely necessary.

MCQ

Interpretive questions – questions

311

MCQ Question 702

Figure 12.9 shows two electrocardiogram records from a patient. Record B was taken one year
after record A was obtained. In these records:
a.

The QRS axis in A is directed to the left rather than to the right of vertical.

The QRS complexes V

, V

and V

in A suggest left, rather than right, ventricular hyper-

trophy.

The change from A to B suggests a return towards normality.

The QRS axis in B is directed downwards rather than upwards.

The inversion of T in leads III and V

in record A indicates myocardial ischaemia.

MCQ

Lead

III

(A)

(B)

Figure 12.9

312

Interpretive questions – answers

Answers for 702

False

The net QRS in lead I is negative, indicating an axis to the right rather than the
left; this is conﬁrmed by lead III having a large positive deflection.

False

The R dominance in V

and the prominent S wave in V

suggest an abnormally

great contribution from the right ventricle in these leads.

True

In record B, V

now shows a normal S wave; V

has lost its S wave to show only

a normal R wave.

True

It is roughly 60

below the horizontal (close to the axis of lead II). The swing from

right (A) to left (B) indicates return of left ventricular dominance, as do the V lead
changes.

False

Occasional T wave inversion is common and usually has no sinister signiﬁcance.

MCQ

Interpretive questions – questions

313

MCQ Question 703

Figure 12.10 shows some relationships between lung volume (increasing upward) and oesoph-
ageal pressure (increasing to the right) during normal tidal breathing. In this diagram:
a.

The intra-oesophageal pressure is equal to atmospheric pressure at point A.

The changes during the respiratory cycle follow the path ABDC.

The slope of the line AD increases when lung compliance increases.

The width of the loop CB increases when airway resistance increases.

AD increases in length during exercise.

MCQ

Intra-oesophageal pressure

Lung v

olume

Figure 12.10

314

Interpretive questions – answers

Answers for 703

False

Intra-oesophageal pressure is similar to intrapleural pressure which is negative
with respect to atmospheric pressure at the beginning of a normal inspiration.

True

In both inspiration (ABD) and expiration (DCA) volume changes lag pressure
changes, thus the relationship is a hysteresis loop, rather than the straight line
AD.

True

Since compliance is volume change per unit pressure change.

True

The greater the airway resistance, the more does air flow lag behind pressure
changes, hence the greater the hysteresis.

True

During exercise, both pressure changes and lung volume changes increase so that
tidal volume increases.

MCQ

Interpretive questions – questions

315

MCQ Question 704

Figure 12.11 shows the visual ﬁeld of a normal left eye as plotted by perimetry. When the eye
is focused on point Y, an object at point:
a.

W is detected in the lower nasal quadrant of the left retina.

Y is detected in the region of the fovea of the macula.

Z rather than at point X may be invisible.

W is appreciated as a result of impulses transmitted in the left rather than the right
optic tract.

V is seen in monocular vision.

MCQ

Figure 12.11

316

Interpretive questions – answers

Answers for 704

True

The image is inverted and reversed with respect to the object.

True

The point focused upon is detected at the macula where visual acuity is greatest.

False

The reverse is the case; the optic disc is medial to the fovea, hence the blind spot
is in the temporal (lateral) part of the ﬁeld of vision.

False

Impulses from the temporal region of the ﬁeld of vision cross the midline at the
optic chiasma.

True

The visual ﬁelds of the two eyes do not overlap for this point.

MCQ

Interpretive questions – questions

317

MCQ Question 705

Samples taken from the ureters of a man with severe one-sided renal artery stenosis gave the
results shown in the table below. Plasma creatinine level was 1 mg/100 ml and the PAH level
was 3 mg/100 ml. In this patient:
a.

Glomerular ﬁltration rate (creatinine clearance) was 10 times as great on the left side as
on the right.

Renal plasma flow was approximately 67 ml/minute on the left.

Renal blood flow was 900 ml/minute on the right (haematocrit

⫽33 per cent).

The right kidney had the narrowed renal artery.

It is likely that he was hypertensive.

Left ureter

Right ureter

Urine volume (ml/minute)

0.2

6.0

Creatinine conc (mg/100 ml)

100.0

10.0

PAH conc (mg/100 ml)

1000.0

150.0

MCQ

318

Interpretive questions – answers

Answers for 705

False

Creatinine clearance (UV/P) was 20 ml/minute on the left and 60 ml/minute
(normal) on the right.

True

From PAH clearance – a very low value.

False

Blood flow

⫽plasma flow⫻1/1⫺Ht⫽300⫻3/2⫽450 ml/minute.

False

The left side had the abnormality.

True

Due to excessive renin release from the ischaemic kidney; the excessive renin
leads to excessive formation of angiotensin I and angiotensin II; the latter con-
stricts blood vessels and increases plasma volume.

MCQ

Interpretive questions – questions

319

MCQ Question 706

Figure 12.12 shows results obtained during a glucose tolerance test on three people. The person
represented by curve B was normal. The oral glucose load was given at time zero. It can be
deduced that:
a.

Curve A is consistent with a diagnosis of diabetes mellitus.

Curve C is more consistent with a diagnosis of an insulin-secreting tumour than of mal-
absorption.

A person showing curve B, who has glucose in the urine 30 minutes after glucose inges-
tion, is likely to have a low renal threshold for glucose.

The renal clearance of glucose two hours after glucose ingestion in patient A is nearer
10 than 30 per cent of the renal plasma flow, assuming a normal renal threshold.

The renal clearance of glucose for the patient showing curve B is likely to be about
60 ml/minute 30 minutes after glucose ingestion.

MCQ

300

200

100

Hours

Blood glucose (mg/100 ml)

Blood glucose (mmol/l)

Figure 12.12

320

Interpretive questions – answers

Answers for 706

True

The fasting glucose level and the peak level are markedly raised and there is
delayed return of blood glucose to the fasting level.

False

Curve C is typical of the flattening obtained with malabsorption; with an insu-
lin-secreting tumour, the fasting level would tend to be low, with a more marked
rise to a peak and a subsequent trough below the initial level.

True

The normal renal glucose threshold is about 180 mg/100 ml (10 mmol/l).

True

About 150/330 of the ﬁltered glucose is being lost, corresponding to a clearance
of 40–50 per cent of the GFR, i.e. about 60 ml which is about 10 per cent of renal
plasma flow.

False

Since blood glucose does not exceed the renal threshold for glucose, renal clear-
ance will be zero.

MCQ

Interpretive questions – questions

321

MCQ Question 707

Figure 12.13 shows mean results of experiments in which sheep fetal (A) arterial pressure, (B)
heart rate, (C) femoral artery blood flow and (D) femoral vascular resistance were measured
before, during and after a period (marked by the rectangle) when the mother was made
hypoxic. The results suggest that:
a.

Maternal hypoxia causes a 50 per cent rise in fetal blood pressure.

The fall in femoral blood flow with maternal hypoxia is due to the slowing of the heart.

Maternal hypoxia causes vasoconstriction in the fetal lower limbs.

The fetal responses are similar to those seen in the diving reflex seen in seals and other
animals that dive under water.

The response might aid survival by redistributing cardiac output towards the brain.

MCQ

(A)

(B)

(C)

(D)

200

150

100

Hours

(mmHg)

(ml min )

–1

mmHg (ml/min )

–1

(beats min )

–1

(After Sanhueza et al. J. Physiol. (2003) 546, 899.)

–1

Figure 12.13

322

Interpretive questions – answers

Answers for 707

False

The increase is not more than 25 per cent – from a mean value around 46 mmHg
to a mean value around 56 mmHg in the second half of the period of hypoxia.

False

Blood flow is not normally a function of heart rate; notice that the change in
heart rate was modest – from around 175 to around 140 beats per minute and it
was accompanied by a rise in arterial pressure (A).

True

The fall in flow despite the increase in perfusion pressure indicates vasoconstric-
tion and this is conﬁrmed by the rise in femoral vascular resistance – resistance
rose about three-fold when flow fell to about one third.

True

Diving animals show a bradycardia and peripheral vasoconstriction when they
dive under water.

True

The vasoconstriction in the lower body diverts a greater fraction of the cardiac
output to the cerebral circulation which does not constrict in response to a
hypoxic stimulus.

MCQ

Interpretive questions – questions

323

MCQ Question 708

Figure 12.14 shows the growth rates of males and females from birth to 20 years. It indicates
that:
a.

Growth for both sexes is most rapid between the ages of 0 and 2 years.

Boys and girls have similar growth rates around age 13–14.

Boys stop growing at a later age than girls.

Boys grow less quickly at age 5 than at age 16.

The growth rate for girls of 12 is less than for boys of 16.

MCQ

9 10 11 12 13 14 15 16 17 18 19 20 21

Age in years

Growth rates in boys and girls

cm per y

ear g

Boys

Girls

Figure 12.14

324

Interpretive questions – answers

Answers for 708

True

But it falls rapidly over this period by about half.

True

They are about the same but the growth rate in girls is decreasing whereas that
of boys is increasing.

True

The curve for boys is about two years to the right of that for girls; girls stop
growing at about 16-18 whereas boys continue to grow until they are about 18-
20.

True

Their height gain per year is much lower at 5 than at 16 years.

True

Boys have a greater growth spurt than girls and on average attain greater adult
height.

MCQ

INTERPRETIVE QUESTIONS

325

EMQs

Questions 709–714

EMQ Question 709

Figure 12.15 shows some of the changes that occur throughout the phases of a menstrual cycle.
For each of the physiological variables a–e below, select the most appropriate option from the
following list of traces.

1. Trace A.

2. Trace B.

3. Trace C.

4. Trace D.

Oestradiol level.

Core temperature.

Luteinizing hormone level.

Progesterone level.

Inhibin level.

Days

Figure 12.16

Figure 12.15

EMQ

326

Interpretive questions – answers

Answers for 709

Option 3

Trace C. Oestrogens produced by the follicular cells of the developing ovum

dominate the follicular phase of the cycle and peak about the time of ovulation; the level
is still somewhat raised during the luteal phase.

Option 1

Trace A. Core temperature tends to rise about the time of ovulation and then

falls again coming up to the following menstruation.

Option 4

Trace D. Luteinizing hormone secretion peaks at about the time of ovulation

(in a similar manner to follicle-stimulating hormone, but its concentration tends to be
greater).

Option 2

Trace B. Progestogens formed by the corpus luteum dominate the luteal

phase of the cycle and cause the endometrium to enter the secretory phase.

Option 2

Trace B. Inhibin is a hormone produced by the ovary that inhibits secretion

of follicle-stimulating hormone by the anterior pituitary gland. It peaks in the luteal phase
of the cycle with a time course similar to the progestogen level.

EMQ

Interpretive questions – questions

327

EMQ Question 710

Figure 12.16 shows the effect of increasing grades of exercise (from rest in period 1 to near
maximal exercise in period 4) on some cardiovascular and respiratory variables. For each of
the traces A–E, select the most appropriate variable from the list below.

1. Oxygen consumption.

2. Cardiac output.

3. Heart rate.

4. Mean arterial pressure.

5. Total peripheral resistance.

Trace A.

Trace B.

Trace C.

Trace D.

Trace E.

EMQ

1400

1200

1000

800

600

400

200

ercentage

Exercise workload

Effect of exercise on some physiological variables

B
C

Figure 12.16

328

Interpretive questions – answers

Answers for 710

Trace A: Option 1

Oxygen consumption. Oxygen consumption can increase during

exercise from a resting value of 0.25 litre/minute to 3 litres/minute (1200 per cent) or
more.

Trace B: Option 2

Cardiac output. Cardiac output increases fairly linearly with

increasing exercise from a resting value of about 5 to a peak value of over 20 litres per
minute.

Trace C: Option 3

Heart rate. Heart rate increases fairly linearly with exercise from

a resting value of about 60 to a maximum of about 180 (220 minus age in years) beats
per minute, a rise to about 300 per cent of the resting value.

Trace D: Option 4

Mean arterial pressure. Though cardiac output rises markedly in

exercise, peripheral resistance falls markedly; rises in mean pressure are usually slight.

Trace E: Option 5

Total peripheral resistance. Total peripheral resistance falls mark-

edly due to vasodilation in the exercising skeletal muscles

EMQ

Interpretive questions – questions

329

EMQ Question 711

Figure 12.17 shows four points on the pressure–volume diagram of a left ventricle. For each
of the descriptions a–e below, select the best option from the following list of points and lines.

1. D

2. C

3. A

4. B

5. DC

6. DA

7. AB

8. CB

9. CD

10. AD

11. BA

12. BC

13. ABCD

14. DCBA

15. DCAB

16. ADCB

The beginning of diastole.

The end of systole.

Isometric contraction.

The segment between two points where the trace would depart maximally from a
straight line.

One cardiac cycle starting with the onset of diastolic ﬁlling.

EMQ

120

Pressure (mmHg)

120

Volume (ml)

Figure 12.17

330

Interpretive questions – answers

Answers for 711

Option 1

D. At the beginning of diastole ventricular volume is around 50 ml and the

pressure is around 120 mmHg (above atmospheric) because the isometric phase of diastole
has not yet occurred.

Option 1

D. At the end of systole, ventricular volume has returned to 50 ml and the

pressure is around 120 mmHg, having fallen from a maximal value around 140 mmHg as
the aortic valve closes.

Option 12

BC. By deﬁnition volume is unchanged during isometric contraction, while

pressure rises from about zero to a level which will open the aortic valve at arterial dias-
tolic pressure, around 90 mmHg; thus isometric contraction is represented by the vertical
line BC.

Option 9

CD. The two segments BC and DA represent isometric systole and isometric

diastole, so are completely straight. During ventricular ﬁlling, AB, there is a small (around
5 mmHg) rise in pressure during atrial systole. In contrast, during the ejection phase of
ventricular systole, CD, the pressure rises from arterial diastolic to arterial systolic (from
around 90 to 140 mmHg) and then falls back to around 120 mmHg as the aortic valve
closes.

Option 13

ABCD. Diastolic ﬁlling starts when ventricular volume is around 50 ml and

its pressure close to atmospheric. The pressure–volume trace then moves to B where ﬁlling
is complete, and continues in an anti-clockwise direction.

EMQ

Interpretive questions – questions

331

EMQ Questions 712

Figure 12.18 shows four points on the flow–volume diagram of the lungs of a healthy young
man. W is the lung volume at total lung capacity and Y is the lung volume at residual volume.
Z and X represent maximal outflow and maximal inflow respectively. The person has breathed
in and out a vital capacity as quickly as possible. For each of descriptions a–e below, select the
best option from the following list of points, lines and areas.

1. W

2. X

3. Y

4. Z

5. WZ

6. ZW

7. ZY

8. YZ

9. WX

10. XW

11. XY

12. YX

13. ZX

14. XZ

15. Totally inside the loop below.
16. Partially outside the loop below.

The line which corresponds most closely to the ﬁrst part of a forced expiratory volume
in one second manoeuvre.

The point at which lung volume is closest to one litre.

The position of the loop during strenuous exercise in the same person.

The ﬁnal part of the manoeuvre of measuring a fast vital capacity.

The point at which intra-alveolar pressure is likely to be most negative.

EMQ

– 6

Air flo

Lung volume

Flow volume diagram for lungs

Figure 12.18

332

Interpretive questions – answers

Answers for 712

Option 5

WZ. The manoeuvre starts at total lung capacity and the volume expired in

the ﬁrst second is measured.

Option 3

Y. The residual volume of a healthy young man is usually a little over a litre.

Option 15

Totally inside the loop. Although volumes and flows increase with exercise,

they are still below the maximal; the loop for tidal breathing is smaller still.

Option 7

ZY. After the ﬁrst second of rapid expiration the person must continue

breathing out until residual volume is reached, usually in a further second or two.

Option 2

X. This is the point of maximal inflow; at this point the pressure gradient

between atmosphere and alveoli is also maximal, with alveolar pressure subatmospheric.

EMQ

Interpretive questions – questions

333

EMQ Question 713

Figure 12.19 shows some of the effects of simulating mildly increased gravitational stress by
lower body suction. For each of the physiological variables a–e below, select the most appro-
priate option from the following list of trends.

1. Trend A.

2. Trend B.

3. Trend C.

Forearm blood flow.

Cardiac output.

Mean arterial pressure.

Total peripheral resistance.

Renin secretion.

EMQ

200

100

Grade of lower body suction

Change from control

Effect of lower body suction

Figure 12.19

334

Interpretive questions – answers

Answers for 713

Option 3

Trend C. The forearm blood flow falls as part of the general vasoconstric-

tion that helps to maintain arterial blood pressure.

Option 3

Trend C. As the blood pools in the lower body due to suction, the ﬁlling

pressure of the heart decreases and so the cardiac output falls.

Option 1

Trend A. During this relatively mild gravitational stress, arterial pressure is

quite well maintained by mechanisms that compensate for the shift of blood volume
towards the feet.

Option 2

Trend B. The shift of blood initiates reflex mechanisms to increase total

peripheral resistance to help to maintain arterial pressure.

Option 2

Trend B. The diminished blood flow to the kidneys with vasoconstriction

related to the fall in cardiac output and output results in the release of renin from the jux-
taglomerular apparatus that again helps to maintain arterial blood pressure.

EMQ

Interpretive questions – questions

335

Question 714

Figure 12.20 shows the effects of intravenous adrenaline and noradrenaline infusions on some
cardiovascular variables. For each event or trace a–e below, select the best option from the fol-
lowing list.

1. Arterial pressure.

2. Heart rate.

3. Cardiac output.

4. Peripheral resistance.

5. The period of adrenaline infusion.

6. The period of noradrenaline infusion.

Event A.

Trace C.

Trace D.

Trace E.

Trace F.

EMQ

150

100

8
6
4

Time (min)

(After Barcroft and Swan (1953) Sympathetic Control of Human Blood
Vessels, Edward Arnold, London.)

Figure 12.20

336

Interpretive questions – answers

Answers for 714

Event A: Option 5

Period of adrenaline infusion. This corresponds to a period of

increased heart rate and widening of the pulse pressure with a fall in diastolic pressure,
whereas at the second event heart rate decreased and both systolic and diastolic pressure
increased, indicating that noradrenaline was infused during period B.

Trace C: Option 2

Heart rate. Adrenaline accelerates the heart but noradrenaline

causes reflex slowing produced by the steep rise in mean arterial pressure. This is the only
scale giving an initial value (around 80) corresponding to a normal (slightly apprehensive)
heart rate.

Trace D: Option 1

Arterial pressure. Adrenaline lowers the diastolic pressure but

noradrenaline raises it. This is the only dual trace corresponding to systolic and diastolic
pressures; the initial value 130/80 corresponds to normal blood pressure.

Trace E: Option 3

Cardiac output. Adrenaline raises cardiac output but noradrena-

line reduces it because of the reflex depression of cardiac activity. Again the scale corre-
sponds to an initially normal/slightly raised cardiac output around 6–7 litres/minute.

Trace F: Option 4

Peripheral resistance. Noradrenaline raises total peripheral resis-

tance because of its predominant effect on alpha adrenoceptors which mediate vasocon-
striction; adrenaline lowers it because of its predominant effect on beta adrenergic
receptors which mediate vasodilation. These units are appropriate for peripheral resis-
tance: from the equation
Mean arterial pressure

⫽Cardiac output⫻Peripheral resistance

we can derive that
Peripheral resistance

⫽Mean arterial pressure/Cardiac output

For the initial state this equals approximately 100/7

⫽14–15 as in F (the units are

mmHg/litre/minute).

Note that for this question it was necessary to consider all aspects of the diagram together,

rather than consecutively.

EMQ

‘A’ wave of venous pulsation in neck, 123
abdominal pressure, 188
ABO blood group see blood group antigens
absolute refractory period, ventricles, 79
absorption, 218, 224, 250, 255

calcium, 255, 502
fat/lipid, 218, 223, 255, 258
glucose, 246, 255, 258
intestinal, 246, 250

impaired, 229

sodium see sodium
vitamin B

, 250, 25 1, 255

see also reabsorption

accommodation for near vision, 351, 385

loss of ability, 385

ACE inhibition, 478
acetylcholine, 292
acetyl-coenzyme A, 644
Achilles (ankle jerk) reflex, 302
acid—base balance see pH
acidosis, 624

bicarbonate administration, 66
metabolic, 41, 508, 641

hypokalaemic acidosis, 444
in renal failure, 647

respiratory, 42, 59, 434, 641, 694, 696

acquired immune deficiency syndrome see AIDS
action potentials, 642

cardiac, 137
nerve fibre, 289

Addison’s disease, 510
adenohypophysis see pituitary gland, anterior
adenosine triphosphate (ATP), 644
adrenal gland

adrenaline secretion, 461
cortex

CRH effects on activity, 512
decreased activity, 510
hormones secreted by, 475
paediatric overactivity, 504

failure, 495
medulla

overactivity, hypertension with, 509
tumour, 485, 509

adrenaline, 461, 467

adrenal secretion, 461
injection/infusion, 101, 452, 714

gastric motility decrease with, 257

adrenoceptors, 279

blockade, 312

ß-adrenoceptors, 337

ß one/two, 337
blockade, 324

adrenocorticotrophic hormone (ACTH), 447,

479

afferent inhibition, 649
age-related changes, 601, 606

body mass, 610
females, 576
lens elasticity, 385
respiratory system/function, 144
special senses, 380, 394

agglutinogens see blood group antigens
AIDS and HIV disease, 57

lymphocytes, 64

air

flow (gas flow) in lungs, 693, 694

see also flow—volume diagrams

in pleural cavity, 171

albumin, plasma, 10, 65
aldosterone, 413, 440

antagonist, 423
secretion, 413, 415

increased, 445

alerting reactions, 648
alimentary tract, 195-260

motility, 252, 257, 260
surgical removal of various parts, 259
see also specific regions

alkaline mucus, secretion, 253
alkalosis

metabolic, 41, 59, 694
respiratory, 41, 43, 45, 694

alpha-adrenoceptors see adrenoceptors
alpha rhythm (EEG), 281
altitude see high altitude
alveolar pressure, 188, 693
alveolar ventilation in breathing, 148
amblyopia, 387
amenorrhoea, 510

secondary, 545

athlete, 663

ammonia, renal handling, 436
amniotic fluid, 542
ampullary crest (crista ampullaris), 390, 646
amylase, 254
anaemia, 35, 62, 701

in gastric juice deficiency, 256
hypoxia in, 194
iron-deficiency, 36, 62, 701
in renal failure, 647

anaerobic activity, 690

metabolism in, fitness measurement, 687

androgens, 505, 520

female secretion, 566

angina, 113
angiotensin I/II, 419, 439
angiotensin-converting enzyme inhibition, 478
ankle jerk reflex, 302
anorexia, 198
anosmia, 394
antibodies, 13

ABO blood group see blood group

antidiuretic hormone (vasopressin), 440, 455, 503

deficiency and insufficient secretion (and diabetes

insipidus), 421, 482, 511

antigens, 22

blood group see blood group antigens

antihaemophilic globulin (factor VIII) deficiency, 54,

anxiety, sporting event, 683
aortic chemoreceptors, 158
aortic valve, 130

incompetence, 119
stenosis, 697

aphasia, 307
apoferritin, 255
appendicectomy, 259
appetite loss, 198
aqueous humour, 360

INDEX

337

338

Index

arousal in competitive sport, 679
arrhythmias

dialysis patient, 441
electric shock causing, 622
sinus, 595

arteries, 98

baroreceptor reflexes, 333
blood analysis, 189

in acid—base imbalance, 59

blood gases see blood gases; carbon dioxide;

oxygen

blood pressure see blood pressure
chemoreceptors, 132
elasticity, 129
fetal, pressure in maternal hypoxia (sheep), 707
leg, narrowing of major vessels, 114
pulse contours, 115
stretch receptors, 132

arterioles, 92

resistance, 96, 129
wall thickness, 129

arteriovenous anastomoses in temperature

regulation, 129

ascending reticular formation, 269
ascorbic acid (vitamin C) deficiency, capillary

haemorrhages, 62

assisted reproduction, multiple pregnancy, 568
astereognosis, 394
asthma, 170

exercise in, 661

astigmatism, 394
asystole see heart, arrest
athletes

maximal exercise, 663
physical fitness see fitness
training, 599, 654
see also exercise

atmospheric pressure, 188

100mmHG, sudden exposure, 618
middle ear equalization with, 391

atonic bladder with overflow, 435
ATP, 644
atria

chemoreceptors, 132
dysfunction, P wave abnormalities, 134
fibrillation, 106
pressure increase in right when lying down, 135

atrial natriuretic peptide, increased secretion, 510
atrioventricular bundle interruption, 118
atrioventricular node, impulse conduction delay,

134

atropine, 314

injection, 612
ocular instillation, 374

audition/hearing, 390-1

audiogram, 370, 699
disorder, 394
sound waves and transmission, 363, 389, 390,

391, 646

auditory ossicles, 391
auditory reflexes, 391
auscultation

blood pressure measurement, 78
bruits, 116
heart, 108, 1 16

automatic bladder, 435
autonomic nervous system, 292, 337

cardiac function and, 81, 86, 333, 337
see also parasympathetic nervous system;

sympathetic nervous system

autoregulation of blood flow, 131
autosomal genetic disorders

dominant, 635
recessive, 625

axon (nerve fibre), 334

action potential, 289
myelinated see myelinated axons
non-myelinated, 290, 334

bacteria, Kupffer cell ingestion of, 253
balance problems, 371, 382
baroreceptor reflexes, 645

arterial, 333

basilar membrane, cochlea, 345, 368, 391
beta-adrenoceptors see adrenoceptors
bicarbonate (HCO

)

administration in acidosis, 66
levels, 189

in acid—base imbalance, 59
in respiratory failure, 59, 647

reabsorption, 442

biceps reflex, 333
bile, 195

intestinal entry, 258
salts, 195, 2 17, 25 1, 255

absorption, 250

biliary system

obstruction, pale stools, 256
stones, 227

bilirubin, plasma, 7
birth see neonates; parturition
bitter taste sensation, 392
bladder

abnormalities, 435
emptying, 426
pressure recording, 422
sympathectomy, 431

bleeding/haemorrhage

arresting see haemostasis
blood volume restoration after, 619
capillaries after, 136
from capillaries see capillaries
chronic gastrointestinal, faecal blood, 128
postpartum, 558
severe, reflex venoconstriction, 135
small skin cut, 12

blind spot, 387
blindness, 387, 388

colour, 373, 388
night, 387
with visual pathway interruption, 376

blood

arterial see arteries
centrifuged, appearance, 34
clotting/coagulation see clotting
CO

see carbon dioxide dissociation curve; carbon

dioxide tension

lactic acid, 655
loss see bleeding
O

see oxygen

Index

339

blood (continued)

pulmonary capillary, 166
stored, 61
viscosity, decreased, 62

blood—brain barrier, 136, 273
blood flow, 133

autoregulation, 131
cerebral, 133
coronary see coronary blood flow
forearm, measurement by venous occlusion

plethysmography, 126, 695

renal, 404, 406, 407
skeletal muscle

in exercising limb, 653
in fainting, 133

skin, 133
splanchnic, in sweating, 133
to tissues/organs (in general), local metabolic

activity affecting, 69

turbulent, 95
velocity, 87
see also circulation

blood gases, 139, 189

in acid—base imbalances, 59
in respiratory failure, 112
see also carbon dioxide; oxygen

blood group antigens (agglutinogens), 2, 33

group A, 5

antibodies (agglutinins), 25

group B, antibodies (agglutinins), 25
in transfusion reactions, 37, 6 1

blood pressure, 70

arterial

adrenaline and noradrenaline (i.v. infusion)

effects, 714

dialysis patient, abnormal, 441
mean see mean arterial blood pressure

auscultatory measurement, 78
high see hypertension
reflex regulation, 132
venous see venous pressure

blood transfusion see transfusion
blood vessels see entries under vascular;

vasculature

blood volume

increased, 60

see also plasma, volume

reflex regulation, 132
restoration after haemorrhage, 619
see also hypovolaemic circulatory failure

blue bloaters, 186
bone, 586

metabolism, 507, 585

bowel see intestine
boys, growth rates, 708

see also males

brain, 648

capillary permeability, 136
function, depressed, 327
oedema, 67
respiratory centre see medulla oblongata
vasculature see cerebral vessels
see also specific parts

brainstem

death, 306, 33 1, 443

brainstem (continued)

reflexes, 333

in pregnancy, 571

sensory pathways, 393

breast (mammary glands), 525

lactating, 503, 512
progesterone causing development, 505

breathing

alveolar ventilation in, 148
divers see divers
Kussmaul, 508
work of, 162
see also ventilation

breathlessness see dyspnoea
bronchi

complete obstruction, 174
smooth muscle contraction, 149

bronchial asthma see asthma
brown fat, 213
bruits, auscultation, 116
Brunner’s glands, 253
brush border, glucose absorption, 258
buffering, 605

by desaturated haemoglobin, 193

burns, fluid disturbances, 67

calcification (bone) disorders, 507
calcitonin (thyrocalcitonin), 465, 507
calcium, 502, 592

absorption, 255, 502
blood levels

fall, causes, 471
raised, 55, 502

one mole, 592

calculi see stones
capillaries, 136, 140

bleeding/haemorrhage from, 58

in vitamin C deficiency, 136

blood values in, 140
density, in fast twitch anaerobic muscle, 690
fluid loss and leakage, 65

in legs, 77

glomerular, hydrostatic pressure, 395, 438
pulmonary, blood in, 166

carbaminohaemoglobin, 193
carbohydrate

absorption, 224
as energy source, 63

carbon dioxide, 146

retention, 179
transport, 146, 160, 193
see also respiratory quotient

carbon dioxide dissociation curve of blood, 161,

698

carbon dioxide tension (PCO

), 139, 698

arterial, 189, 613

in acid—base imbalances, 59
effects of raised PO

, 155

in respiratory failure, raised, 112

carbonic anhydrase, 594

inhibitor, 429

carboxyhaemoglobin, 193
cardiac sphincter contraction, 252
cardiovascular system, 68-138

see also circulation; heart

340

Index

carotid bodies, 142

chemoreceptors, 158

CCK see cholecystokinin
cell organelles, 640

see also specific organelles

central inhibition, 649
central venous pressure see venous pressure
centrosomes, 640
cerebellum, 270

disease, 322

movement disorder, 336

cerebral cortex, 285

damage, 320

cerebral hemispheric damage, 336

left, 332
see also stroke

cerebral oedema, 67
cerebral vessels/vasculature, 138

blood flow, 133
resistance

decreased, 127
increased, 127

cerebrospinal fluid, 21
cerebrovascular accident see stroke
cervical spinal cord, lower

hemisection, 301
transection, 323, 340

chemical mediators, site of pain, 335
chemoreceptors

aortic, 158
arterial, 132
atrial, 132
carotid, 158
coronary artery, 132

chest pain

cardiac (angina), 113
non-cardiac, 128

chest wall compliance, 163
childbirth see parturition
childhood factors, short stature in adults, 486
children

endocrine disorders, 504, 507
fovea centralis, 381
secondary sexual characteristics see sexual

characteristics, secondary

see also infants; neonates; puberty

chloride reabsorption, 444
cholecalciferol see vitamin D
cholecystectomy, 259
cholecystokinin (pancreozymin; CCK; PZ), 260, 477

gallbladder contraction and, 252, 257
gastric emptying and, 260

choleliths (gallstones), 227
cholesterol, 63, 225
cholinergic nervous system, 292

heart rate and, 337
see also muscarinic receptors

cholinesterase, 643
chorionic gonadotrophin, human, 518

in pregnancy, 575

chromosomal disorders

chromosome 21 non-dysjunction, 504
sex, 504, 549

chronic obstructive disease, pulmonary (COPD), 175,

182, 186, 190

chymase (rennin), 254
ciliary muscles, 385
circadian rhythms, 588
circle of Willis, 138
circulation

changes, 127, 138
failure

central, 105
hypovolaemic, 697
peripheral, 105, 647

fetal see fetus
neonatal, 516
see also blood flow; cardiovascular system

claudication, intermittent, 114
clearance, renal, 397, 411, 417, 439
clotting/coagulation, 24

disorders, 58

coagulation see clotting
cochlea, basilar membrane, 345, 368, 391
cold, 659

digital artery spasm, 414

cold water, sudden application, 638
colectomy, 259
collecting ducts/tubules, 412, 436
colliculi, inferior, 391
colloid osmotic pressure, 65

ratio of intravascular hydrostatic pressure to, 637

colon, 106
colour blindness, 373, 388
coma, 331

hyperglycaemic, 494
hypoglycaemic, 331, 494

compliance

chest wall, 163
lungs, 151, 163, 693, 703

conditioned reflexes, 649
cones, retinal, 346, 361, 386
consciousness, impaired, dialysis patient, 441
constipation, 245
contraception, methods, 556, 569
convoluted tubules see tubules
coronary arteries, 138

chemoreceptors, 132
disease, lipids as risk factor, 63
resistance, decreased, 127

coronary blood flow (to myocardium incl. ventricle)

left ventricle, 68
poor/inadequate

angina, 113
ECG, 134

corpus luteum, 534
corticosteroids see glucocorticoid; mineralocorticoid
corticosterone, 505
corticotrophin (adrenocorticotrophic hormone;

ACTH), 447, 479

corticotrophin-releasing hormone, 512
Corti’s organ, 390
cortisol, alpha globulin binding to, 505
coughing, 181
cranium (skull) and hearing, 391
creatinine clearance, 439
cretinism, 504
crista ampullaris, 390, 646
critical fusion frequency, 386
cuneatus, 393

Index

341

cupula, 390
Cushing’s syndrome, 492
cutaneous physiology see skin
cyanosis, 178

‘pink puffers’ vs ‘blue bloaters’, 186

cystometrogram, 422

dark adaptation, 344, 348, 386
dead space, respiratory, 164
death

brainstem, 306, 33 1, 443
fetal, 567
local tissue, vascular obstruction causing, 125
perinatal, multiple pregnancy, 568

defaecation, 200
deglutition (swallowing) reflex, 197, 333
delta waves (EEG), 303
deoxyribonuclease, 265
depolarization, nerve cell membrane, 286
dextrose, 5% and 50%, 66
diabetes insipidus, 421, 482, 510
diabetes mellitus, 500

insulin treatment, 662
ketoacidosis, 189, 33 1, 497
ketosis, 496
oral glucose tolerance test for, 476, 500, 706
severe, 483, 491
type-1 (insulin-dependent), and exercise, 689
type-2, 509

dialysis, 424, 441
diarrhoea, severe, 236

metabolic acidosis, 641

dichromatism, 388
dietary energy intake, appropriate, 684

see also food; malnutrition

digestive tract see alimentary tract
digital artery spasm with cold, 414
dihydroepiandrosterone, 505
dilution indicators, 29

cardiac output estimation, 99

2,3-diphosphoglycerate, 674
diplopia, 387
disaccharidases, 251, 254
divers, breathing

air at 30m depth, 177
helium instead of nitrogen, 621

DNase (deoxyribonuclease), 265
dominant autosomal genetic disorders, 635
dopamine, 643
dorsal (posterior) column of spinal cord, 393

damage, 316

double vision, 387
Down’s syndrome, 504
ductus arteriosus, 138
dumping syndrome, 259
duodenum

fat in, 252, 257
pancreatic juice lack in, 241
passage of gastric contents to, 216
ulcer see peptic ulcer

dwarfism, 504
dynamic vs static exercise, 76, 656
dyspnoea (breathlessness)

‘pink puffers’, 186
ventilation associated with, 191

ear

inner, 390

hair cells, 355, 390, 646

middle, 375, 391
see also audition

ear drum (tympanic membrane), 353, 358, 389
ECG see electrocardiography
ectopic beats (extrasystoles), ventricular, 120
EEG see electroencephalography
egg (ovum), fertilization, 514
ejaculation/ejaculate see semen
elastic recoil, leg muscle/tendons, 668
elasticity

arteries, 129
lens with ageing, loss, 385
lung in emphysema, loss, 173

electric shock causing ventricular fibrillation, 622
electrical potentials, 642
electrocardiography, 90, 1 09, 134, 137, 702

treadmill exercise danger signs, 657, 670

electroencephalography, 276

␣ rhythm, 281

␦ rhythm, 303

embolism, pulmonary, 121
emesis see vomiting
emmetropia, 385
emphysema, pulmonary elastic tissue loss, 173
endocrinology see hormones
endolymph, 342, 390
endopeptidases, 254
endoplasmic reticulum, 584
endorphins, 335
endurance fitness, Olympic level, 676
endurance running see running
energy, 644

dietary intake, appropriate, 684
sources of

carbohydrate, 63
fat, 63

enkephalins, 335
enteric nervous system, polypeptide secretions, 260
enterochromaffin cells, 253
enterokinase, 253
enzymes

digestive, 203, 204, 20 7, 25 1, 253, 254
intracellular, 640

eosinophils, 23
epididymis, 574
equilibrium potential, 298
erection, penile, 535, 569
erythrocytes (red cells), 9

antigens see blood group antigens
breakdown, 4
circulating, 14
CO

in, 193

formation, increased, 40

erythropoietin, 444

increased secretion, 510
transplanted kidney, 443

Eustachian tube, 391
excitatory post-synaptic potential, 268
exercise (and sport), 670-91, 710

capillary pressure in muscle during, 136
hyperaemia in skeletal muscle during, 83
isometric vs isotonic, 76, 656

342

Index

exercise (continued)

maximal, 629

athlete, 663
ventilation increase, 685

metabolic rate in see metabolic rate
syncope/pre-syncope during, 128
see also athletes

exophthalmos, thyroid overactivity, 506
external inhibition, 649
extracellular fluid

decreased, 60
intracellular vs, 1
osmolality rise, 628

extrapyramidal motor system disease, 336

parkinsonism, 310, 336

extrasystoles, ventricular, 120
eye

atropine application, 374
involuntary oscillatory movements (nystagmus),

379, 388

left, visual field, 367, 704
protrusion of eyeball in thyroid disease, 506
refraction system, 354, 385
visual acuity see visual acuity
see also vision and specific parts of eye

facial nerve and taste sensation, 392
factor VIII deficiency, 54, 58
faeces/stools

bulky liquid, with colectomy, 259
chronic loss of blood in, 128
discharge, 200
pale, in biliary obstruction, 256
see also constipation; diarrhoea

fainting/syncope

in exercise, 128
heart rate decrease, 135
skeletal muscle blood flow in, 133
vasovagal, 103, 135

fat (lipid), 63

absorption, 218, 223, 255, 258
brown, 213
in duodenum, 252, 257
emulsification, 251
increased body fat, 208
stores (adult), 231
transport, 253

fatty acids, free (non-esterified), plasma, 226
fatty meals, cholecystectomy causing indigestion,

259

fear reaction, 648
females (women)

androgen secretion, 566
growth rates, 708
life cycle, 576
males and, reproductive comparisons, 522
oestrogen and progesterone administration,

554

pregnancy see pregnancy
subfertility, 557, 569

fertility, reduced (incl. infertility), 557, 569

males, 564, 569
see also contraception

fertilization of ovum, 514
fetal haemoglobin, 523

fetus, 544

circulation, 138, 529, 547

arterial pressure in maternal hypoxia (sheep),

707

death, 567
prematurity in multiple pregnancy, 568
size at birth, 532

fever, 623
fibrinogen conversion to fibrin, 28
Fick principle, 578

cardiac output estimation, 100, 578

fitness (physical) of athletes, 650

endurance, Olympic level, 676
measurement, 687

flexor (withdrawal) reflex, 645
flow—volume diagrams of lungs, 712
fluid

body, 1-67

osmolality see osmolality
renal, 398, 402, 421, 436, 442

dialysis, 424

follicle-stimulating hormone, 570
food

appetite loss, 198
energy expenditure increase after ingestion, 644
salivation seeing or thinking about, 645
specific dynamic action of, 219, 644
see also dietary energy intake; malnutrition

foot, pain sensation, 267
foramen ovale (sphenoid), 389
foramen ovale valve (heart), 130
forced expiratory volume in one second (FEV

), 184,

192, 696

forearm blood flow, 713

measurement by venous occlusion

plethysmography, 126, 695

fovea centralis, 341, 381
fungiform papillae receptors, 646

GABA, 643
gallbladder

contraction, CCK-induced, 252, 257
surgical removal (cholecystectomy), 259

gallstones, 227
gamma-amino-butyric acid, 643
gas(es)

blood see blood gases
flow in lungs see air, flow; flow—volume

diagrams

gastrectomy, 235, 259
gastric physiology see stomach
gastrin release, 252, 260
gastrocolic reflex, 252
gastrointestinal tract see alimentary tract
generator potentials, 642
genetic disorders, 625, 632, 635
girls, growth rates, 708

see also females

glomerulus

capillaries, pressures, 395, 438
filtration, 438, 439

in renal transplantation, 443

glossopharyngeal nerve and taste sensation, 392
glucagon, pancreatic, 456

increased and excessive secretion, 508, 511

Index

343

glucocorticoid, 505

excessive production, 492, 511
injections, effects, 451

glucose, 508

absorption, 246, 255, 258
administration (

⫽dextrose), 5% and 50%, 66

blood/plasma levels, 400

abnormal see hyperglycaemia; hypoglycaemia

metabolism, 508
renal handling, 700, 705
in urine, 439, 440

glucose tolerance test, oral, 476, 500, 706
glycogen, 63

skeletal muscle stores, 686

glycosuria, 439, 440
Golgi apparatus, 604
gonadotrophin (gonadotrophic hormone)

human chorionic see chorionic gonadotrophin
pituitary see follicle-stimulating hormone;

luteinizing hormone

gonadotrophin-releasing hormone (GRH), 512,

569

granulocytes, neutrophil, 11
gravitational stress, 713
growth, males and females rates of, 708
growth factors, hepatic secretion, 503
growth hormone, 453, 512

secretion, 468

excessive, causes and effects, 493, 509
impaired, 498

growth hormone-inhibiting hormone, 260
GRP, 260
gustation see taste
gyrus, postcentral, 393

receptor blockers and gastric secretion, 257

haematocrit (packed cell volume), 38, 701

fall in late pregnancy, 135

haemodialysis, 441
haemoglobin

carbamino group bound to, 193
CO combined with, 193
CO

combined with, 193

concentration in anaemic hypoxia, 194
desaturated, buffering of H

ions by, 193

fetal, 523

haemolytic disease of newborn, 33
haemorrhage see bleeding
haemostasis

disorders, 58
platelets in, 6

hair cells (ear), 355, 390, 646
head, angular acceleration, 646
headache, 326
hearing see audition
heart, 75

arrest (asystole), 102

ECG, 134

auscultation, 108, 1 16
autonomic nervous system and, 81, 86, 334, 337
block, complete, 118
disease/abnormalities (in general)

exercise tolerance limits with, 674
treadmill exercise test for see treadmill exercise

test

heart (continued)

failure, 110, 647

see also ventricles, failure

impulse conduction, 137

delay, 134

murmurs, 116
muscle see myocardium; ventricles, muscle
output, 91

adrenaline and noradrenaline (i.v. infusion)

effects, 714

in anaemia, compensatory rise, 62
exercise and, 710
gravitational stress and, 713
techniques of estimation, 99, 1 00, 578

Purkinje system, 93, 137
rate, 337

adrenaline and noradrenaline (i.v. infusion)

effects, 714

decrease in fainting, 135
in exercise, 710

rhythm disturbances see arrhythmias
sounds

first, 71, 85
second, 71

sympathetic drive to, 81, 86
valves, 130

disease, 119, 697

heat (and hot environments), 668, 682

adaptation, 630, 658, 672, 682
exercise in, 658, 672

height, short (adults), childhood factors, 486
helium, divers breathing, 621
hemianopia, 388
hemiplegia, right-sided stroke, 321
hepatic physiology see liver
hereditary disorders, 625, 632, 635
Hering—Breuer reflex, 132
high altitude, 152, 636

acid—base imbalance, 59, 641
arterial blood values, 59, 189, 194, 692
effects of moving to, 636
exercise hindrance, 677
sudden exposure to 100mmHG atmospheric

pressure (e.g. aircraft), 618

histamine receptor type 2 blockers and gastric

secretion, 257

HIV disease see AIDS
hormone(s), 445-512

renal actions, 440
reproductive/sex, 570

in pregnancy, 575

hormone replacement therapy, 576
hot environment see heat
human chorionic gonadotrophin see chorionic

gonadotrophin, human

hydrogen ions

active exchange of sodium ions for, 444
buffering see buffering
concentrations, 597

urine vs plasma, 437

excess, elimination, 439
see also pH

hydrostatic pressure, intravascular

colloid osmotic pressure, ratio of, 637
glomerular capillaries, 395, 438

344

Index

5-hydroxytryptamine see serotonin
hyperaemia in skeletal muscle during exercise, 83
hypercalcaemia, 55, 502
hyperglycaemia

coma, 494
exercise-related risk (diabetic), 689

hyperhidrosis, limb, 634
hyperinsulinism, 511
hyperkalaemia see potassium
hypermetropia, 384
hyperosmolality, 67
hyperparathyroidism, 499, 509
hyperphosphaturia, 502
hypertension

portal, 244
systemic, 104

adrenal medullary overactivity causing, 509
renal causes, 510, 705
severe, 107

hyperthyroidism (thyroid hormone excess secretion;

thyrotoxicosis), 128, 449, 484, 509

exophthalmos, 506

hyperventilation

dialysis patient, 441
reflex, 191
voluntary, 157, 19 1

hypoglycaemia, 508

coma, 331, 494
exercise-related risk (diabetic), 689

hypokalaemia, 627
hypokalaemic acidosis, 444
hyponatraemia, 48
hypo-osmolality, 67
hypoparathyroidism, 481
hypothalamus

circulation, 138
hormones, 457, 512
reflexes, 333
temperature regulation and, 648

hypothermia

coma, 331
oxygen consumption decrease, 135

hypothyroidism, 480

congenital (causing cretinism), 504

hypovolaemic circulatory failure, 697
hypoxia, 666, 674

anaemic, 194
in chronic respiratory failure and disease, 185,

189

hypoxic, 189, 194
maternal, fetal arterial pressure (sheep), 707

immunity, gut, 258
incontinence

overflow, 435
stress, 435

indicator dilution technique see dilution indicators
infants

compared with adults, 633
newborn see neonates

infections (local) with saliva deficiency, 256
infertility see contraception; fertility
inherited disorders, 625, 632, 635
inhibin, 570, 709
innervation, stomach, 215

inspiration, 145, 153

early, 150, 590

insulin, 440, 463, 487, 508

deficiency, 508
diabetics

administration, 662
requirement with physical exertion, 689

excessive secretion, 511
structure, 474

insulin-dependent diabetes mellitus and exercise,

689

insulin-like growth factors (somatomedins), 453,

503, 512

intermittent claudication, 114
interstitial cells, testis, 531
interstitial fluid, renal medulla, 442
intestine (bowel; gut)

absorption see absorption
activity, factors affecting, 257
bile entering, 258
motility, 252
mucosal cells see mucosal cells
obstruction, 233
pain receptors, 305
Peyer’s patches, 258
secretions, 203, 25 1
small see small intestine

intra-abdominal pressure, 188
intra-alveolar pressure, 188, 693
intracellular vs extracellular fluid, 1
intracranial pressure, raised

causes, 329
effects, 304
treatment, 309

intra-oesophageal pressure see oesophagus,

pressure

intrapleural pressure, 693
intrauterine device, 556, 569
intravenous infusions, 31, 56, 66
intrinsic factor, 255

deficiency, 256

ions

equilibrium potentials, 298
and ions channels (in cell membranes), 596

nerve, 286, 29 1

iris muscle, 339, 385
iron absorption, 250, 255
iron deficiency anaemia, 36, 62, 701
isometric exercise vs isotonic exercise, 76, 656
isometric ventricular contraction, 89
isotonic vs isometric exercise, 76, 656

jaundice, 234
jejunal mucosal cells and proximal convoluted

tubules, similarities, 583

jugular venous pulse and pressure, 110

ketoacidosis, diabetic, 189, 33 1, 497
ketosis, diabetic, 496
kidney

blood flow, 404, 406, 407
calculi, 502
chronic failure, 420, 430, 432

metabolic acidosis, 641
transplantation in, 427, 443, 620

Index

345

kidney (continued)

clearance, 397, 411, 417, 439
failure (and damage)

acute, 432, 647
chronic see subheading above
dialysis, 424, 441
progressive, treatment, 433
severe, arterial blood values, 59, 189

functional regions, 442

see also specific parts

glucose handling, 700, 706
hormonal actions, 440
hypertension related to, 510, 705
water retention see water

knee jerk (quadriceps/patellar) reflex, 261, 333, 334,

645

in spinal cord transection, 340

Kupffer cell, ingestion of bacteria, 253
Kussmaul breathing, 508

labour, 572

premature, 561

lactase, 251, 254

deficiency, 256

lactation, 503, 512
lacteals, 258
lactic acid, blood, 655
laryngeal obstruction, sudden, respiratory acidosis,

641

legs

capillary fluid loss, 77
elastic recoil of muscle/tendons, 668
narrowing of major arteries, 114
oedema, 32
see also limb

lemniscus, medial, 393
lens

elasticity loss with ageing, 385
maximum convexity, 385

leukaemia, 64
Leydig cells, 574
light

bright, visual acuity impairment in, 383
from object to right of visual axis, 357
poor, dark adaptation, 344, 348, 386

light reflex, pupillary, 356, 385
limb

exercise-related pain, 673
lower see leg
skeletal muscle blood flow to, in exercise, 653
sweating, excessive, 634

limbic system, 648
lipase, 63, 25 1
lipids see fat
liver, 205

cells, 222
failure and dysfunction, 237, 242, 647

coma, 331

growth factors secreted by, 503

long-sightedness, 384
loop of Henle, 442, 444
lower motor neurones see motor neurone
lungs

chronic obstructive disease (COPD), 175, 182,

186, 190

lungs (continued)

compliance, 151, 163, 693, 703
elastic tissue loss in emphysema, 173
expansion, 153
flow—volume diagrams, 712
function (respiratory function), 190

age and, 144
tests, 190, 696

gas/air flow, 693, 694
residual volume, 154
stretch receptors, 132
surfactant see surfactant
surgical removal of one, 180
vessels see pulmonary vasculature
volume, and oesophageal pressure, 703

luteinizing hormone, 503, 570, 573, 709
luteinizing hormone-releasing hormone, 512
lying down, 591

right atrial pressure increase, 135

lymph, 26
lymphocytes, 15

in AIDS, 64

lymphoid aggregations (Peyer’s patches) in intestine,

258

lysosomes, 591, 640

macular damage or sparing, 388
males (men)

growth rates, 708
infertility, 564, 569
pre- and postpubertal state, differences, 526
women and, reproductive comparisons, 522

malnutrition limiting exercise tolerance, 678
maltase, 251, 254
mammary glands see breast
marathon running see running
mass, body see weight
mean arterial blood pressure

50% fall, renal responses, 404
in exercise, 710
gravitational stress and, 713

medulla, renal, interstitial fluid, 442
medulla oblongata

respiratory centre see respiratory centre
vomiting centre, 335

melaena, 128
melanocyte-stimulating hormone (MSH), 503
melatonin, 448
membranes

cell/plasma, 588

ion channels see ions
nerve see nerve cell
potentials, 642, 649
skeletal muscle, 18

intracellular (organelles), 640

men see males
menopause, 562
menstrual cycle, 513, 539, 573, 709
menstruation, absence see amenorrhoea
metabolic acidosis see acidosis
metabolic activity (local) affecting blood flow to

tissues, 69

metabolic alkalosis, 41, 59, 641, 694
metabolic energy per unit mass, fat and

carbohydrate, 63

346

Index

metabolic equivalent of oxygen consumption

(METS) in exercise, 667, 681, 691

metabolic rate

in exercise

doubling, 584
maximum, 660

measurement, 232, 644
in pregnancy, increased, 571
resting/basal, 644

metabolism, 665

anaerobic, fitness measurement, 687
in exercise, 665

micelles, 253
microsomes, 640
microtubules, 640
micturition, voluntary, 409
milk

breast, ejection, 503
digestion, 254
intolerance, 256

mineralocorticoid, 505
mitochondria, 579
mitral valve, 130
monoamine oxidase, 643
monocytes, 8
mortality see death
motor neurone (somatic), lower, 266
motor neurone disease/lesions, 336

lower, 311, 332
upper, 332

movement disorders, 336
mucosal cells, intestinal

glucose absorption, 246
proximal convoluted tubules and, similarities, 582

mucus, alkaline, secretion, 253
multiple sclerosis, 336
murmurs, auscultation, 116
muscarinic receptors, 292

blockade by atropine, 314

muscle

potassium uptake, increased, 508
various types compared, 293, 298, 339
see also skeletal muscle; smooth muscle;

ventricular muscle and specific muscles

muscle fibres, skeletal see skeletal muscle fibres
muscle spindle, 338, 646

stimulation of sensory ending, 283

myelinated axons/nerve fibres, 290, 334

pain and, 335

myocardium (cardiac muscle), 137, 339

blood flow see coronary blood flow
infarction, plasminogen activators, 127
non-cardiac muscle compared with, 297
see also ventricles, muscle

myocytes, skeletal, membranes, 18
myoglobin levels, 690
myopia, 372
myxedema, 506

near point, 385
near vision, accomodation for see accommodation
neck, ‘A’ wave of venous pulsation in, 123
neonates/newborns, 519, 540, 551-2

cardiovascular system, 516
haemolytic disease, 33

neonates/newborns (continued)

poor physical condition, features, 560
size at birth, 532

neoplasm see tumour
nephron, 436

osmolality, 402, 436

nerve cell membranes

depolarization, 286

potentials in efferent neurones, 649

resting, permeability, 291

nerve endings, bare, 646
nerve fibre see axon
nerve impulses, 274, 282

foot pain, sensation, 267
pre-synaptic neurones, 295
from utricle receptors, 364

nerve supply, stomach, 215
nervous systems, inhibition in, 649
neurology, 261-340
neuromuscular junction

skeletal muscle, 262
sympathetic transmission, 272

neuromuscular system, 261-340
neurotransmission, synaptic

at neuromuscular junction, sympathetic, 272
neurotransmitter action, inhibition produced by,

649

neurotransmitter release, inhibition produced by,

649

neutrophil granulocytes, 11, 64

reduced counts, 47

newborns see neonates
night blindness, 387
nitrogen

balance, 214
divers breathing helium instead of, 621

non-unmyelinated axons, 290, 334
noradrenaline

excessive secretion, 511
intravenous infusion, 101, 452, 714
vasoconstriction and, 131

normocytic anaemia, 62
nucleic acids, digestion, 154, 25 1
nucleus, cell, 599, 640
nucleus gracilis, 393
nutritional status and exercise tolerance, 678

see also dietary energy intake; food

nyctalopia, 387
nystagmus, 379, 388

obesity, 248, 617

treatment, 611

obstructive airways disease, chronic (COPD), 175,

182, 186, 190

occipital cortex and vision, 648
Oddi’s sphincter, 258
oedema

cerebral, 67
legs, 32
optic disc, 313
in ‘pink puffers’, 186

oesophageal-gastric sphincter contraction, 252
oesophagus

pressure, 188

lung volume and, 703

Index

347

oesophagus (continued)

smooth muscle tone, 249

oestrogen (incl. oestradiol)

administration to women, 554
in menstrual cycle, 709
in pregnancy, 575
see also hormone replacement therapy

olfactory cells, 343
olfactory system, 350

impaired sense of smell, 378, 394

Olympic level endurance fitness, 676
ophthalmology see eye
optic disc oedema, 313
oral glucose tolerance test, 476, 500, 706
organ of Corti, 390
organ transplantation see transplantation
organelles, cell, 640

see also specific organelles

osmolality, 19, 65, 440

abnormal, 67
extracellular fluid, rise, 628
renal/urinary, 402, 421, 436, 440, 442

osmotic pressure

colloid see colloid osmotic pressure
of plasma, total, 600

ossicles, auditory, 391
osteoblast activity, 507
osteomalacia, 507
osteoporosis, 507, 669
otolith organ, 390
oval foramen see foramen ovale
oval window, 389
ovaries, 537

dysgenesis, 504

overflow incontinence, 435
ovulation

contraceptives inhibiting, 569
failure, 559

ovum, fertilization, 514
oxygen

consumption/uptake, 194

decrease in hypothermia, 135
exercise, 652, 710
increased, various causes, 210
maximal, in physical fitness measurement,

687

measurement, 644
metabolic equivalent of (METS), 667, 681,

691

content (blood)

fetal circulation, 529
mixed venous, 169

dissociation curve (blood), 161, 174, 192,

674

dissolved/in solution, 192
partial pressure (blood) see oxygen tension
saturation, 192, 192
supply/delivery, 187, 194

to ventricular muscle, 117

total available, 186, 194
transport, 192, 194
see also respiratory quotient

oxygen debt, 167
oxygen tension/partial pressure (PCO

), 139, 692,

698

oxygen tension/partial pressure (PCO

) (continued)

arterial, 189, 613

in acid—base imbalances, 59
at high altitude, 59, 189, 194, 692
in respiratory failure, low, 112
urinary system response to long-standing

increase in, 434

oxyntic cells, 258
oxytocin, 503

in labour, 572

P value and treatment superiority, 626
P waves, 134, 137

abnormalities, 109, 134
see also P-T interval

pacemaker potentials, 642
packed cell volume see haematocrit
paediatrics see children
pain, 335, 673

chest see chest pain
cutaneous, 325
exercising limb, 673
foot, sensation, 267
head, 326
loss of sensation, 267
peptic ulcer, 230
receptors, 296, 646

gut and urinary tract, 305

severe, 330
thalamic, 335, 393
visceral, 315

pancreatectomy, 259
pancreatic glucagon see glucagon
pancreatic juice/secretions, 204, 25 1, 253

lack/deficiency, 256

in duodenum, 241

pancreatitis, acute, 63
pancreozymin see cholecystokinin
papilloedema, 313
para-aminohippuric acid (PAH), 406, 443

in renal artery stenosis, 705
urine vs plasma concentrations, 437

parasympathetic nervous system, 278, 292

blockade, 318
generalized activity, 337

parathormone, 440, 473, 502

increased secretion (and hyperparathyroidism),

499, 509

parathyroid gland, loss of function, 481
parietal cells, 258
parkinsonism, extrapyramidal motor system disease,

310, 336

parturition (childbirth), 530

fetal size, 532
see also labour

patellar reflex see knee jerk
peak flow rate/peak expiratory flow rate (PFR;

PEFR), 190, 696

penis, erection, 535, 569
pentagastrin, 257
peptic (gastroduodenal) ulcer

healing, 238
pain, 230

peptide bond splitting, 254
perfusion pressure, regional, decreased, 127

348

Index

perinatal death, multiple pregnancy, 568
peripheral circulatory failure, 105, 647
peripheral resistance, total

adrenaline and noradrenaline (i.v. infusion)

effects, 714

exercise and, 710
gravitational stress and, 713

peristalsis, 252
peritoneal dialysis, 441
pernicious anaemia, 62
peroxisomes, 640
Peyer’s patches, 258
pH (and acid—base balance), 20

disturbances, 41-5, 641, 694

arterial blood analysis, 59
at high altitude, 59, 641

investigation of acid—base status, 44, 189
see also buffering; hydrogen ions, concentration

phaeochromocytoma, 485, 509
phosphate, 502

extracellular and renal clearance, 440
increased urinary excretion, 502

physical activity see exercise
physical fitness, athletes, 650
pigmentation, skin, increased in Addison’s disease,

510

pink puffers, 186
pituitary gland, 138, 464

anterior (adenohypophysis), 489

decreased secretion, 510

paediatric deficiency, 504
surgical removal, 501
tumour, 493

placenta, 527
plasma

albumin, 10, 65
bilirubin, 7
dialysis fluid components and their levels in,

424

free fatty acids, 226
glucose see glucose
hormone half-lives, 445
renal flow following in renal transplantation, 443
sodium, fall, 48
total osmotic pressure, 601
urinary solutes and their levels in, 424
volume, decreased, 60

plasma membrane see membranes
plasminogen activators in myocardial infarction,

127

platelets, 27, 63

in haemostasis, 6
lack/low count, 58, 63
stickiness/aggregation, 63

plethysmography, venous occlusion, forearm blood

flow measurement by, 126, 695

pleural cavity

air in, 171
pressure, 693

pneumonectomy, 180
pneumothorax, 171
polycythaemia, 510, 614
postcentral gyrus, 393
posterior column (spinal cord) see dorsal column
postoperative physiology, 609

postpartum blood loss, 558
postsynaptic inhibition, 649
postsynaptic potentials, 642

excitatory, 268
inhibitory, 294

postural reflexes, 648
potassium

depletion, 52
high levels (blood/extracellular fluid), 53

dialysis patient, 441

low levels, 627
muscle uptake, increased, 508
renal handling, 418, 444
urine vs plasma concentrations, 437
see also hypokalaemic acidosis

pregnancy, 521, 528, 571, 575

⫹ previous deliveries, risks, 565

diagnosis, 550
first child with over-35 year olds, 563
haematocrit fall, 135
multiple, 568
physiological changes in, 541
postpartum blood loss, 558
see also fetus; labour; parturition

premature beats (extrasystoles), ventricular, 120
premature fetus, multiple pregnancy, 568
premature labour, 561
presbycusis, 394
presbyopia, 385
pressure sensation, 393
pressure—volume diagram in left ventricle, 711
pre-synaptic inhibition, 649
pre-synaptic neurones, volley of impulses, 295
preterm fetus, multiple pregnancy, 568
preterm labour, 561
progesterone, 505, 570

administration to women, 554
menstrual cycle and, 573, 709
in pregnancy, 575

prolactin, 470
prolactin-inhibiting hormone, 512
proprioception, 280, 393
prostatic obstruction, chronic, 435
proteins

ingestion, 602

absorption, 218, 224

peptide bond splitting, 254
ribosomal synthesis, 640

prothrombin deficiency, 58
P-T interval, 134
puberty

males, differences before and after, 526
precocious, 546
see also sexual characteristics, secondary

pulmonary non-vascular tissue see lung
pulmonary valve, 130
pulmonary vasculature, 138, 159

capillary blood, 166
embolism, 121
resistance, 72, 159

pupil

dilatation, 349
light reflex, 356, 485

Purkinje system (heart), 93, 137
pyrexia (fever), 623

Index

349

QRS axis and complexes, 109, 702
quadriceps (patellar/knee jerk) reflex, 261, 333,

334

R waves, 109
rage reaction, 648
rapid eye movement sleep, 300, 606
Raynaud’s phenomenon, 414
reabsorption, tubular, 399, 403, 436, 439, 440,

444

active vs passive, 439
bicarbonate, 442

recessive genetic disorders

autosomal, 625
sex-linked, 632

red cells see erythrocytes
reflex(es), 132, 26 1, 333, 645

see also specific reflexes

reflex hyperventilation, 191
refraction system, eye, 354, 385
refractive error, 394
refractory period, absolute, ventricles, 79
regional perfusion pressure, decreased, 127
relative density, 16
REM sleep, 300, 606
renal artery stenosis, 705
renal system see kidney; urinary system/tract
renin, 419, 440

increased secretion, 510

in gravitational stress, 713

rennin, 254
reproductive system, 513-75
residual volume, 154
respiratory acidosis, 42, 59, 434, 641, 694, 696
respiratory alkalosis, 41, 43, 45, 641, 694
respiratory centre (

⫽medulla oblongata), 140, 19 1

exercise and, 688

respiratory cycles, 693
respiratory disease

chronic

acid—base imbalance, 189, 641
hypoxia, 189

exercise limits, 675

respiratory failure, 112, 647

arterial blood values, 59
chronic, 172

hypoxia in, 185

respiratory pressures, 188
respiratory quotient, 209
respiratory system/tract, 139-94

sudden complete obstruction, 630

reticular formation, 648

ascending, 269

retina, 386

cones, 346, 361, 386
pigments, 366, 386
rods, 346, 360, 366, 386

rhesus disease, 33
rhodopsin, 366, 386, 387
ribosomes, 641
rickets, 507
rods, retinal, 346, 360, 366, 386
round window, 389
running, endurance (incl. marathons), muscle fibres,

651

sacral spinal segment reflexes, 333
saline, normal and hypertonic, 66
saliva, 196, 2 11

deficiency, local infections with, 256
secretion, 251, 254

increased, 199
in seeing/thinking about food, 645

salt

excretion, increased, 510
taste sensation, 347, 392

saltatory conduction, 277
scotoma, 387, 388
secretin, 477
semen

ejaculate, 538, 574
ejaculation, 543, 569

semicircular canal, 390

hair cells, 355

seminal vesicles, 574
seminiferous tubules, 574
sensation

disturbances, 319, 332, 394

in spinal cord transection, 340

pain see pain

senses, special, 341-94
sensory ending of muscle spindle, stimulation,

283

sensory nerve supply, muscle, 338
sensory pathways, 393
sensory receptors, 265, 646
serotonin (5-HT), 643

secretion, 253

sex chromosomes

numerical anomalies, 504, 549
recessive genetic disorders, 632

sexual characteristics, secondary, development

early, 546
failure, 555

short bowel syndrome (with 90% removal of small

intestine), 240

short-sightedness, 372
short stature, adults, childhood factors,

486

sinuatrial node, 84, 137
sinus arrhythmia, 596
skeletal muscle, 275, 339

blood flow, in fainting, 133
cell membrane, 18
in exercise/sport, 651, 690

blood flow to limb muscle, 653
capillary pressure, 136
elastic recoil in legs, 668
hyperaemia, 83
training, 654

glycogen stores, 686
histological and physiological study, 299
in labour, 572
neuromuscular junction, 262
other muscle types compared with, 293, 297
stimulation of sensory ending of muscle spindle,

283

tone, reduction, 308

skeletal muscle fibres, 264

endurance running, 651
fast and slow twitch, 687, 690

350

Index

skin

bleeding from small cut, 12
blood flow, in sweating, 133
pain, 325
pigmentation increase in Addison’s disease, 510
vasodilatation following skin damage, 645

skull and hearing, 391
sleep, 581

deep, 271
hormones in, 446
REM vs non-REM, 300

small intestine, 221

absorption see absorption
motility, substance P and, 260
smooth muscle, 339
surgical removal of 90%, 240

smell sensation see entries under olfactory
smooth muscle (visceral), 293

bronchial, contraction, 149
iris, 339, 385
oesophageal, tone, 249
other muscle types compared with, 293, 298
in pregnancy, 571

in labour, 572

small intestinal, 339

Snellen letter charts, 386
sodium (ions), 65, 440

absorption, 218, 250, 255

reabsorption, 440, 444

active exchange for hydrogen ions, 444
depletion, 50
drugs affecting renal transport, 428
hormones affecting clearance, 440
osmolality and, 65
plasma levels

compared with urine, 437
fall, 48

retention, 49, 50
see also salt

sodium bicarbonate administration in acidosis, 66
sodium-dependent glucose transporter, 255
somatomedins, 453, 503, 512
somatostatin, 260
sound(s), heart see heart, sounds
sound waves and transmission, 363, 389, 390, 391,

646

spasm, digital artery, with cold, 414
special senses, 341-94
specific dynamic action of food, 219, 644
specific gravity, 16
spermatozoa, 515

formation/development (spermatogenesis), 524,

574

hormones affecting, 503, 512
testicular temperature affecting, 569

sphincter(s)

cardiac, contraction, 252
Oddi’s, 258
VIP causing relaxation of, 260

spinal cord, 284

left half damage, 332
lower cervical region see cervical spinal cord
posterior/dorsal column see dorsal column
reflexes, 333
transection, 323, 340

spinothalamic tracts, 393
spiral organ (organ of Corti), 390
splanchnic blood flow, 133
splanchnic resistance, increased, 127
splenic capillary permeability, 136
sport see exercise
squint (strabismus), 377, 387
ST segment depression, 134
standard deviation of series of observations,

587

stapedius muscle, 389
stapes, foot plate, 389
static vs dynamic exercise, 76, 656
stature, short (adults), childhood factors, 486
steatorrhoea, 256, 259
stereocilia, 390
sterilization, 556
steroids see glucocorticoid; mineralocorticoid
stomach, 202, 2 12

effects of modifying function, 228
emptying, 228, 243

CCK inhibiting, 260

innervation, 215
motility, fat in duodenum decreasing, 257
passage of contents to duodenum, 216
surgical removal (gastrectomy), 235, 259
ulcer see peptic ulcer

stomach juices (incl. acid), 207

deficiency, 256
rennin found in infants, 254
secretion, 202, 20 7, 220, 243, 25 1, 258

agents affecting, 257

stones (calculi)

biliary, 227
urinary tract, 509

renal, 502
ureteric, 436

stools see faeces
strabismus, 377, 387
stress incontinence, 435
stretch receptors

arterial, 132
knee jerk, 646
pulmonary, 132

stroke (cerebrovascular accident), 336

one cerebral hemisphere

physical activity limitations, 680
right-sided, hemiplegia, 321

stroke work, left ventricular, 697

denervated heart, 97

substance P and small intestinal motility, 260
substantia nigra, 648
sucrase, 251, 254
surfactant, pulmonary, 143

lack, 548

surgery, postoperative physiology, 609
swallowing reflex, 197, 333
sweating

limb, excessive, 634
skin blood flow, 133
in spinal cord transection, 340

sweet taste sensation, 392, 646
sympathetic nervous system, 272, 292, 337

bladder function following cutting of nerve

supply, 431

Index

351

sympathetic nervous system (continued)

exercise and

in diabetes mellitus, 689
in endurance running, 688

generalized activity, 287, 337
heart and, 81, 86, 337
in spinal cord transection, loss of motor function,

340

vasoconstriction and, 131

synaptic transmission see neurotransmission
syncope see fainting

T wave, 134, 702
taste sensation (gustation), 392

receptors, 362, 369
salty, 347, 392
sweet, 392, 646

tectorial membrane, 390
temperature

core, menstrual cycle, 709
regulation (thermoregulation)

arteriovenous anastomoses in, 129
hypothalamus and, 648
spinal cord transection and, 340

sensation, 393
testicular, affecting spermatogenesis, 569
see also cold; heat; hypothermia

tendons in legs, elastic recoil in sport, 668
tensor tympani muscle, 389
testis

interstitial cells, 531
surgical removal (adult), 553
temperature affecting spermatogenesis,

569

testosterone secretion, 533

testosterone, 570, 574

secretion, 517, 533

tetany, 488
thalamus (and sensation), 393

pain, 335, 393

thermoregulation see temperature
thirst, 30
thoracic (chest wall) compliance, 163
thrombocytopenia (low platelet count), 58, 63
thyrocalcitonin (calcitonin), 465, 507
thyroglobulin, 506
thyroid gland, 506

overactivity see hyperthyroidism
removal, effects, 490
secretory activity-increasing factors, 459
underactivity (deficient hormone secretion) see

hypothyroidism

thyroid-stimulating hormone (TSH), 462, 506,

512

thyroid-stimulating hormone-releasing hormone

(TRH; thyrotrophin-releasing hormone),
512

thyrotrophin (TSH), 462, 506, 512
thyrotrophin-releasing hormone (TRH), 512
thyroxine (T

), 472, 506

deficiency, 506

tinnitus, 394
touch sensation, 393

impaired, 394

transcortin, 505

transfusion, blood, 61

massive, 58, 6 1
multiple repeated, 61
reactions, 37, 6 1

transplantation

rejection, minimizing/prevention, 46, 616
renal, 427, 443, 620

transport maximum, 403
treadmill exercise test, cardiac abnormality, 670

ECG signs, 657, 670

tricuspid valve, 130
triglycerides, splitting, 251
triiodothyronine (T

), 506

trisomy 21 (Down’s syndrome), 504
trypsinogen, 253
tubules, renal

collecting, 412, 436
distal convoluted, 405, 436
fluid in, 398, 402, 421, 436
proximal convoluted, 398, 409, 414, 436, 442

drugs affecting sodium transport in, 428
jejunal mucosal cells and, similarities, 583

reabsorption see reabsorption
secretion in, 401

active, 439

transport maximum, 403
see also nephron

tumour

adrenal medullary, 485, 509
pituitary, 493

Turner’s (XO) syndrome, 504, 549
twin pregnancy, 568
tympanic membrane, 353, 358, 389

ultrafiltration, 577
unmyelinated axons, 290, 334
upper motor neurone lesion, 332
urea, 408

blood/plasma levels

dialysis patient, raised, 441
in liver failure, 647
urine vs, 437

clearance, 439

ureters

calculi, 436
in renal artery stenosis, 705

urethra, chronic obstruction, 425
urinary system/tract, 390-444

pain receptors, 305

urination (micturition), voluntary, 409
urine, 415

acute retention, 435
solutes, 437

urobilinogen, 239
uterine smooth muscle in labour, 572
utricles, 359, 364, 390

vagus/vagal nerve, 288, 338

endurance running and, 688

Valsalva manoeuvre, 582, 594

labour, 572

valve

cardiac see heart, valves
venous, 129

vas deferens, 574

352

Index

vascular resistance, 80

arteriolar, 96, 129
cerebral see cerebral vessels
coronary, decreased, 127
pulmonary, 72, 159
splanchnic, increased, 127

vasculature, 129

obstruction causing local tissue death, 125
tone, and endurance running, 688
see also specific (types of) vessels

vasoactive intestinal polypeptide, 260
vasoconstrictor nerves, 131
vasodilatation in skin following damage, 645
vasodilator metabolites, 131
vasopressin see antidiuretic hormone
vasovagal fainting/syncope, 103, 135
veins, 74

valves, 129

venous blood, mixed, oxygen content, 169
venous capacity in severe haemorrhage, reduced, 135
venous occlusion plethysmography, forearm blood

flow measurement by, 126, 695

venous pressure

central

lowered, in peripheral circulatory failure, 647
raised, in heart failure, 647

standing at rest, 82

venous pulsation in neck, ‘A’ wave of, 123
ventilation, 156, 19 1

alveolar, breathing and, 148
control, 191
increased, various causes, 156, 508

maximal exercise, 685

reflex regulation, 132
see also breathing; hyperventilation

ventilation/perfusion ratio, 147

impaired, 183

ventricles

absolute refractory period, 79
blood flow (coronary) see coronary blood flow
extrasystoles, 120
failure in LV, 124
fibrillation, electric shock causing, 622
filling, 73
function in LV, 697
muscle contraction

isometric, 89
in LV, strength increases, 88

muscle oxygen supply, 117
pressure—volume diagram in LV, 711
repolarization, T wave, 134
stroke work in LV see stroke work

vestibular disease, unilateral, 382
VIP, 260
viscus/viscera

pain, 315
smooth muscle see smooth muscle
wall distension, 252

vision, 385-8

dark adaptation, 344, 348, 386
long-sightedness, 384
loss see blindness
near, accomodation for see accommodation
occipital cortex and, 648
short-sightedness (myopia), 372
various disturbances, 385, 387, 388

visual acuity, 352, 386

impairment in bright light, 383

visual field, left eye, 367, 704
visual pathways, interruption, 376
visual threshold, 386
vital capacity (VC), 165, 184, 192, 696
vitamin A and vision, 387
vitamin B

absorption, 250, 25 1, 255
deficiency, 62
intrinsic factor and see intrinsic factor

vitamin C deficiency, capillary haemorrhages,

vitamin D (and cholecalciferol), 469

deficiency, 255, 502
hydroxylation, 502

vomiting, 247

metabolic alkalosis, 694

vomiting reflex, 333, 335

warfarin, 58
water

absorption, 250
channels (kidney), 444
cold, sudden application, 638
drinking, 603

excessive, 67

excretion, increased, 510
immersion, 659

to chest level, 608
survival at 15°C with life jacket, 615