Physiology of Blood
amazing facts about blood
• The human body manufactures 17 million red blood cells per second. If stress precipitates a need the body can produce up to 7 times that amount. (That’s up to 119 million red blood cells per second).• It only takes 20 to 60 seconds for a drop of blood to travel from the heart, through your body, and back to the heart again.
• Cows have 800 (and possibly more) blood types.
• George Washington was bled to death by doctors, who were treating him for a cold. Bloodletting was a common medical practice in those times in order to remove “dirty blood,” when in reality it only weakens the patient. Half or more of his blood was removed within a few hours.
• The human cornea extracts oxygen directly from the air. It has no blood supply.
• There is about 0.2 milligrams of gold in our bodies, most of which is in our blood. However, you would need to bleed 40,000 people dry just to collect enough blood to make an 8-gram souvenir.
• Mosquitoes prefer blood type O to any other.
• Pregnant women have about 50% more blood by week 20 of pregnancy than they did before they conceived.
• A 2014 study published in the journal Neurology found those with blood type AB were twice as likely to experience memory problems as those with type O blood.
• All blood isn’t red. Crabs have blue blood. Earthworms and leeches have green blood. Many invertebrates, such as starfish, have clear or yellowish blood.
Outline
• 1. describe the blood components and hemopoiesis.• 2. describe red blood cell, its function, and explain the mechanism for regulation of its production.
• 3. expound the plasma proteins and their functions.
• 4. understand the composition, types, forms, synthesis, destruction and abnormalities of Hb.
• 5. characterize the types of anemia.
• 6. explain the types, functions, and the formation of white blood cells.
• 7. describe the types of immunity and the development of the immune system.
• 8. understand the inflammatory process.
• 9. expound blood types, blood incompatibility, and transfusion reaction.
• 10. understand platelets and their functions.
• 11. describe hemostasis and blood coagulation.
• 12. explain fibrinolysis and the anticlotting mechanisms.
• Objectives after studying this chapter, you should be able to . .
FUNCTIONS OF THE BLOOD
1. Transport of O2, nutrients and hormones to the tissues and carries CO2 to the lungs and other products of metabolism to the kidneys to be excreted.
2. Participates in the regulation of body temperature, pH and electrolyte concentrations of interstitial fluid within the normal ranges through a constant exchange of molecules with the interstitial fluid.
3. Blood also serves essential body protective functions, such as combating invading microorganisms, mediating inflammation, initiating immune responses to foreign materials, and maintaining hemostasis.
electrolytes
glucoseurea
lipids
albumin
globulinsfibrinogen
RBCs
WBCsplatelets
such as
TYPES
ALBUMIN (4.5 g/dl) (58%)GLOBULINS (2.5 g/dl) (38%)
( , , )FIBRINOGEN (0.3 g/dl) (4%)
FUNCTIONS1- Exert colloid osmotic pressure.
2- Act as buffers.
3- Transport hormones and other substances in blood.
4- Provide the body with immunity.
5- Involved in blood clotting.
6- Act as a source for rapid replacement of tissue proteins.
In the early weeks of embryonic life
In the Yolk sacAfter 12 weeks gestation
In the liver, spleen, lymph nodesLater on and after birth
In the bone marrow of all bones
After 20 years of age
In the bone marrow of only flat bones and upper femur and humerusHEMOPOIESIS
Reticulocyte count is used as a clinical measurement of erythropoietic activity0.5%-1.5% are Reticulocytes
RED BLOOD CELLS
RBCs• Non nucleated discs.
• Biconcave in shape;
• lack mitochondria,
• Incapable of aerobic respiration (use anaerobic glycolysis)
• High surface area /volume ratio
• - maximum surface area
• - greatest deformability
• After 120 days, they die in the spleen
• Normal RBC count:
• male 5,200,000±300,000/µL
• female 4,700,000±300,000/µL
• RBC count varies with age, sex, altitude.
ERYTHROPOIESIS
Basic substances required: Proteins, Iron, Vit.B12, Folic acid, Vit.B6.ERYTHROPOIESIS
HAEMOGLOBIN (Hb)globular molecule consisting of 4 subunits.
each subunit contains a heme molecule and a polypeptide chain.
the polypeptides form the globin portion of Hb.
Hemoglobin molecule
each heme contains an iron ion (Fe+2) that can combine reversibly with one O2 molecule.
each Hb molecule can carry 4 molecules of O2.Normal adult Hb types
Hb A 2 2 95-97%
2 alpha and 2 beta chains
Hb A2 2 2 2.5%
2 alpha and 2 delta chainsHb F 2 2 < 2%
2 alpha and 2 gamma chainsalpha chain 141 a.a.
beta chain 146 a.a.
delta chain 146 a.a.
gamma chain 146 a.a.
Forms of normal Hb
OxyHb Hb + O2CarbaminoHb Hb + CO2
CarboxyHb Hb + CO
SulfHb Hb + Sulfur
MetHb Fe+2 Fe+3 (oxidation)
Normal Hb concentration
male 13.5 - 17.5 g/dL
female 11.5 - 15.5 g/dL
newborn 21 g/dL
Hb F has a higher O2 affinity than Hb A.
This decreases O2 delivery to the tissues.
Hb synthesis
Begins in proerythroblastsMature RBCs can not synthesize Hb