lect on wbc body fluid module medical students

lect on wbc body fluid module for medical and applied medical students' reference

1. LECTURE 32- LEUCOCYTES: WHITE BLOOD CELLS (WBC)-I By Dr Shamshad Begum.loni Lecture notes

2. Objectives: Describe the different types of leucocytes on the basis of structure and functions Explain the development of leucocytes (leucopoiesis) List the functions of different types of leucocytes. Describe the mechanism of phagocytosis Suggested reading- Guyton and Hall “Textbook of Medical Physiology”12thed (pg423-425, 432, 1024) Ganong’s Review of Medical Physiology 23thed (pg522- 523 Current Medical Diagnosis and treatment ed 2010 ( pg 457,850-851,)

3. Granulocytes: Neutrophils- 65-75% Eosinophils- 1-4% Basophils- <1% Agranulocytes: Monocytes- 4-8% Lymphocytes- 20-45%

4. 1: Neutrophils 65-75% 2: Eosinophil 1-4 % 3: Basophils <1% I: Granulocytes : II: Agranulocytes : 1: Monocytes 4-8 % 2: Lymphocytes 20-45% Types of leukocytes

5. 65-75% Two types of granules : Granules take up both acidic and basic dyes Granules Contain peroxidases, hydrolytic enzymes, and defensins (antibiotic-like proteins) Neutrophils are our body’s bacteria slayers Neutrophils (Polymorphonuclear leukocytes )

6. Functions of neutrophils D efensive function when bacteria invade the body: 1] Margination : Neutrophils aggregate and stick to the damaged capillary walls. 2] Chemotaxis: Some substances such as degenerative products, bacterial toxins & complement system released at site of infection lead to attraction of leucocytes from near capillary (<100  distance) to migrate towards the inflamed area (positive Chemotaxis). Some bacterial toxins repel neutrophils(Negative Chemotaxis).

7. Functions of neutrophils 3] Diapedesis: WBCs can squeeze themselves through the pores of the healthy capillaries to outside. In infected area these pores increase in size to facilitate Diapedesis. 4] Amoeboid movement: WBCs are motile cells and move by amoeboid motion by 40 µ/min .

8. 5 ] Phagocytosis : Power of leucocytes to engulf foreign materials as bacteria, toxins and dead cells. Then ingest these material via proteolytic enzymes of lysosomes. Bactericidal agent hydrogen peroxide (H 2 O 2 ) help to kill bacteria. A neutrophil can phagocytize 5-20 bacteria before the neutrophils die and form pus . 6] Opsonization : Makes the foreign materials more susceptible for phagocytosis

9. 2% of all blood leukocytes Have red-staining, bilobed nuclei Have red to crimson granules Functions Weak phagocytes action. Increased in parasitic infections ( ascaris ) and allergic conditions. Eosinophils

10. By diabedesis, amoeboid movement and chemotaxis they attack the parasites and release substances to kill them. They increased in allergic conditions by the release of eosinophil chemotactic factor. Eosinophils phagocytose the antigen-antibody complexes and release substances to neutralize the histamine. Produce profibrinolysin  fibrinolysin which digest fibrin clot .

11. Basophils 0.5-1% U- or S-shaped nuclei Contains large, purplish-black (basophilic) granules with histamine Function: Histamine – inflammatory chemical acts as a vasodilator and attracts other WBCs (antihistamines counter this effect ). Both Basophils and mast cells liberate heparin in the blood, that prevents blood coagulation and thus help removal of fat particles from the blood after a fatty meal .

12. 3–7 % The largest leukocytes Have purple-staining, U/ kidney-shaped nuclei Leave the circulation, enter tissue, & differentiate into macrophages Function: These macrophages help the functioning of T and B lymphocytes by presenting the antigen to these cells. Releases many chemical substances to increase the inflammatory and allergic reactions against organisms Monocytes

13. Functions of Monocytes Phagocytosis as in neutrophils but more powerful effect . Monocytes secretes : 1. Interleukin-1 (IL-1). 2. Colony stimulating factor (M-CSF). 3. Platelet-activating factor (PAF). Examples of tissue macrophages : Kupffer cells in liver, alveolar macrophages in lungs & macrophages in spleen.

14. 20-45 % Have large, dark-purple, circular nuclei with a thin rim of blue cytoplasm. Found mostly enmeshed in lymphoid tissue (some circulate in the blood ). Two types of lymphocytes: T cells and B cells T cells - attack foreign cells directly B cells give rise to plasma cells, which produce antibodies. Lymphocytes: Most important cells of the immune system

15. Leucopoiesis Origin: G ranulocytes and Monocytes formed from the bone marrow only. Lymphocytes & plasma cells formed in the lymphatic tissues such as lymph node, spleen, thymus, tonsils, bone marrow & Peyer’s patches of GIT. 75 % of the bone marrow form WBCs, its number is less than RBCs count because it has short life span.

16. Leucopoiesis O riginate from hemocytoblasts

17. Life span: Granulocytes : 4-8 hours in the circulation & 4-5 days in the tissue. In infection there is rapid destruction. Monocytes : 10-20 hours in the circulation then enter the tissue to become tissue macrophages & then can live for months. L ymphocytes : V ariable according to the body need. They circulate in between the lymphatic tissue and the blood.

18. A: PHYSIOLOGICAL VARIATIONS 1. Age: I nfants : ≈ 20,000 / c mm C hildren:10,000 - 15,000/ cmm . Adults : 4,000 - 11,000/ cmm . 2. Sex: M ales >females . 3. Diurnal variation : Minimum in early morning & maximum in the afternoon. Increases Decreases Exercise: Emotional anxiety Pregnancy Menstruation Parturition Sleep

19. B: Pathological Leukocytosis: Neutrophila: Increase number of neutrophils Infections : all types acute / chronic, bacterial,/viral / fungal . Inflammation: as rheumatic fever. Tissue damage: as trauma, burn. Malignant tumors . Smoking .

20. Eosinophilia :In Allergic conditions as asthma, hay fever, skin allergy, Parasites, Leukemia . Basophilia : In allergy or leukemia Monocytosis : In chronic infections as TB or in leukemia. Lymphocytosis : In chronic viral/bacterial infections & in leukemia .

21. Leukemia: It is a malignant disease of bone marrow causing marked increase in WBCs may reach 500.000/mm 3 . Leukemia is associated with anemia and bleeding tendency (due to decrease in bone marrow area responsible for RBCs and platelet synthesis respectively)

22. Leucopenia It is decrease in the total leucocyte count below 4.000/mm 3 . In this condition the body is not protected against infections and death may occur. Caused by: Bone marrow depression by radiation, drugs as in cancer chemotherapy. Some bacterial infections as typhoid fever, brucellosis. Some viral infections as AIDS, influenza, hepatitis.