Blood physiology

Lec.5 October 2017

White Blood Cells or leucocytes

Objectives
1.morphology
2.classifications
3.counts
4.leucopoiesis
Life span
5.movements
4. functions

morphology

spherical cell with a nucleus, white in color because it lacks Hb, in stained preparations white blood cells (WBCs) attract stain, whereas RBCs remain unstained.

Classifications: according to presence or absence of granules in cytoplasm:

1.Granulocytes: cytoplasm contains granules
a.Neutrophils. b. Eosinophils. c.Basophils.
2. Agranulocytes: have agranular cytoplasm and subdivided into
a.Lymphocytes. b. Monocytes.


WBC count
a.Total WBC count: there are normally 4000-11000 WBC/c.mm of human blood in both male and female. Average value in normal adult is 9000 WBC's/c.mm. b. Differential WBC's count which indicates the percentage (%) of each of five kinds of leukocytes in total WBC count
. Neutrophils: 60-70%
Eosinophils: 1- 4%
Basophiles: 0.5-1%
Monocytes: 2- 8%
Lymphocytes: 20- 30%

Leukopenia: WBC count lower than normal and can indicate destruction of red marrow by radiation, drugs, tumors or a deficiency of vitamin B12 or foliate.Leukolytosis: is an abnormally high WBC count. Bacterial infection causes leukocytosis .
Leukemia: a tumor of the red marrow. Leukemia is characterized by greatly increased numbers of abnormal WBC's in the circulating blood

Leucopoiesis: is the differentiation and proliferation of leukocytes.

Life span: in circulation are few hours to years
Movements :Most leukocytes are mobile, exhibiting amoeboid movement which is the ability to move like an amoeba by putting out irregular cytoplasim projections. Leukocytes leave the circulation and enter tissue by diapedesis (a process in which they become thin and elongated and slip between or in some cases walls). The leukocytes can then be attracted to foreign materials or dead cells within the tissue by chemotaxis

functions

General functions of WBC our body have a special system for combating the different infections and toxin agents. This system composed of the blood leukocytes and tissue cells derived from leukocytes. These cells work together to prevent disease
Protect the body against invasion of extrinsic pathogens.
Save the organism from overrun by abnormal cells.


Specific Functions of Different types of Leukocytes
Neutrophils: 1. the neutrophils have been called the body’s first line of defense against bacterial infection. In patients with bacterial infection the neutrophil count is greatly increased (neutrophilia). Lack of neutrophils called neutropenia.
Basophiles:. in allergic reactions basophiles count are elevated.
Eosinophils:. Release enzymes that kill some parasite so in patients with parasitic infection eosinophil numbers greatly increased.
Monocytes: Leave the circulation, enter tissues, enlarge and transformed into macrophages which are important in late stages of infection. Produce chemicals such as prostaglandins, interferons and complement that are important in immune system response. Macrophages are given specific names such as dust cells in lungs and kupffer cells in liver.
Lymphocytes:. Types are T-lymphocyte. 2. B-lymphocytes which differentiated into plasma cells that produce antibodies or immunoglobulin's (Igs). These antibodies responsible for destroying foreign antigens. 3. Natural killer cells.
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