blood physiology

1. Blood Physiology
White blood cells (WBCs) (leucocytes)
Dr. Dina Hamdy Merzeban
Lecturer of Medical Physiology
www.facebook.com/merzeban physiology
http//:slideshare.net/ merzeban

2. White blood cells (WBCs) (leucocytes)
They are “true cells” : they contain nucleus
Number: 4000-11,000/mm3
Function: protection of body as part of immune system
1-Attack and destroy bacteria and pathogens
2-Remove dead cells and tissues (phagocytosis)
Most WBC’s are motile by amoeboid motion (pseudopodia) and
they squeeze out of capillaries into tissue spaces

3. Leucopoiesis
WBC’s have different lifespans
 can live for hours to a lifetime, though most have short
lifespan, most WBC’s live < 1 week although some live
for years
WBCs usually formed from stem cells in bone marrow
or in lymphatic tissue and needs vitamin B12, proteins
and pentose nucleotides.
Old WBCs destroyed in reticuloendothelial system.

4. White Blood Cells
• Morphology
Spherical cell with a nucleus
• Classifications
1. Granulocytes: cytoplasm contains granules
• a. Neutrophils.
• b. Eosinophils.
• c. Basophils.
2. Agranulocytes: have agranular cytoplasm and subdivided into
• a. Lymphocytes.
• b. Monocytes.

6. the numbers of each type per unit of blood are clinically
important = differential WBC count

7. Life span of WBCs & Platelets
Cell In blood In tissue
 Neutrophil  4-8 hours  4-5 days
 Monocyte  10-20 hours  Months
(Macrophage)
 Platelets  4 day (half life)
 Lymphocytes
 ( blood↔ lymphoid tissue)
 Months -Years  Month - Years

8. 1.Neutrophils
 60-70% of circulating WBC’s
 Also called band cells, stab cells or polymorph nuclear cells (PMN’s)
 Contain neutrophilic granules
 live for 6 hours.
They are highly phagocytic cells (microphage)
 Attracted to sites of inflammation & release toxic chemicals (eg
hypochlorite and superoxide).
They attack bacteria and some fungi.

9. White Blood Cells

10. 2-Eosinophils (2-4%)
contains acidic stained granules
They are weak phagocytic cells
 They increase in allergic condition and parasitic infestatio
3-Basophiles (1%):
contains basic stained granules
 They store heparin, histamine, bradykinin and serotonin

11. 4-Monocytes:
the largest WBCs, have kidney shaped nuclei.
Formed in bone marrow, when enter tissues become
tissue macrophage.
Highly phagocytic, digest bacteria, synthesize
complement & interferon.
Play role in cell mediated immunity as they act as
antigen presenting cells.

12. 5. lymphocytes:
 25-33% of circulating WBC’s
 Formed in lymph nodes, spleen, thymus, some in bone marrow
 Life span (from days-months)
 there are 3 types
B lymphocytes: transformed into plasma cells responsible for
humoral immunity through production of antibodies (Ig).
T lymphocytes: responsible for cell mediated immunity
 Natural killer cells (non B, non T lymphocytes): act as
defense against viruses& malignant cells.

13. Leukocyte Disorders
Leukocytosis
 Total WBC count >11,000/µL,
in acute infections and inflammation e.g. appendicitis
Leukemia
cancer characterized by uncontrolled production of large
numbers of nonfunctional WBC’s
leucocytic count as high as 400,000/µL .
the patient may be anemic with increased liability to infection


14. Leukocyte Disorders
Leukopenia
total WBC count <3,000/mm3 (agranulocytosis) , fatal.
causes:
 bone marrow depression or irradiation
 viral infection as influenza, measles, mumps, chickenpox,
poliomyelitis
 lead poisoning.

16. Hematology in Old Age
 less intrinsic factor is produced, less absorption of
vitamin B12 ------> anemia
Atrophy of kidneys may reduce erythropoietin which
could also affect erythropoiesis
Thrombosis increases as plaques of atherosclerosis in
blood vessels builds

17. the numbers of each type per unit of blood are clinically
important = differential WBC count

19. Life span of WBCs & Platelets
Cell In blood In tissue
 Neutrophil  4-8 hours  4-5 days
 Monocyte  10-20 hours  Months
(Macrophage)
 Platelets  4 day (half life)
 Lymphocytes
 ( blood↔ lymphoid tissue)
 Months -Years  Month - Years