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Question : Describe five types of leucocytesm,with the help of diagrames,Add a note on their functions.

Answer»

Solution :(1) Leucocytes or White Blood Corpuscles (WBCs) are colouroess, nucleated, amoeboid and phagocytic cells.
(2) Their size ranges between 8 to 15 `mu`m. Total WBC count is 5000 to 9000 WBCs/cu mm of blood. The average life spam of a WBC is about 3 to 4 days.
(3) They are formed by leucopoiesis in red bone marrow, spleen, lymph nodes, tonsils, thymus and Payer's patches, whereas the dead WBCs are destroyed by PHAGOCYTOSIS in blood, liver and lymph nodes.
(4) Leucocytes are mainly divided into two types, viz., granulocytes and agranulocytes.
(5) Granulocytes : Granulocytes are cells with granular cytoplasm and lobed nucleus. Based on their staining properties and shape of nucleus, they are of three types, viz. neutrophils, eosinopohils and basopohils.
(I) Neutropohils :
(i) In neutrophils, the cytoplasmicgranules take up neutral stains.
(ii) Their nucleus is three to five lobed.
(III ) It may undergo changes in structure hence they are called polymorphonuclear lelucocytes or polymorphs.
(iv) neutrophilsare about `70%` of total WBCs.
(v) They are phagocytic in function and engulf microorganisms.
(II) Ecosinophils or acidophils :
(i) Cytoplasmic granules of eosinophils take up acidic dyes such as eosin. They have bilobed nucleus.
(ii) Ecosinopohils are about `3%` of total WBCs.
(iii) They are non-phagocyticin nature.
(iv) Their NUMBER increases (i.e. eosinophilia )during allergic CONDITIONS.
(v) They have anti-histamine propertiy.

(III) Basophils :
(i) The cytoplasmic granules of basophils take up basic stains such as methylene blue.
(ii) They have twisted nucleus.
(iii) In size, they are smallest and constitute about `0.5%` of total WBCs.
(iv) They too are non-phagocytic.
(v) Their function is to release heparin which acts as an anticoagulant and histamine that is involved in inflammatory and allergic reaction.
(6) Agranulocytes : There are two typesof agranulocytes, viz. monocytes and lymphocytes. Agranulocytes do not show cytoplasmicgranulesand their nucleus is not lobed. They are of two types, viz.lymphocytes. and monocytes.
(I) Lymphocytes :
(i) Agranulocyte with a large round nucleus is called lymphocyte.
(ii) They are about `30%` of total WBCs.
(iii) Agranulocytes are responsible for immune response of thebody by producing antibodies.
(III) Monocuytes :
(i) Largest of all WBCs having large kidney shaped nucleus are monocytes. They are about `5%` of total WBCs.
(ii) They are phagocytic in function.
(iii) They can differentiate into macrophages for engulfing micro-organisms and removing cell debris. Hence they are also called scavengers.
(iv) At the site of infections they are seen in more enlarged form.


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