WBCs PDF - Defensive Function of Blood
Document Details
Tags
Summary
This document provides a detailed overview of the defensive function of blood, focusing on white blood cells (WBCs). It highlights the types of WBCs, their functions, and mechanisms in the immune response. The document also covers various aspects of the human immune system.
Full Transcript
Defensive function of the blood General Physiology Theoretical BMS 114 The white blood cells ( leukocytes ) - Mobile units of the protective system. - No Hb. - Formed mainly in the Bone marrow. - Classified according to the presence or absence of g...
Defensive function of the blood General Physiology Theoretical BMS 114 The white blood cells ( leukocytes ) - Mobile units of the protective system. - No Hb. - Formed mainly in the Bone marrow. - Classified according to the presence or absence of granules in their Cytoplasm into: 1- Granular Leukocytes. 2- Agranular Leukocytes. Types of leukocytes Granular Leukocytes 1- Neutrophiles The most numerous type ( 60-70 %) Life span : 6 hours Origin : bone marrow. Function : - Phagocytosis ( the first line of defense against bacteria) - Acute inflammation (by lysosomal enzymes). 1- Margination 2- Diapedesis 3- Amoeboid movement 4-Chemotaxis Break down products. Bacterial toxins. Complement fragments. leukotriens 5-Opsonization 6- Phagocytosis Opsonization : IgG , complement surround the bacteria (facilitates phagocytosis). Ingestion of bacteria (endocytosis) Lysosomal enzymes+ O2 free radicals + H2o2 (bactericidal). Neutrophils die in the inflamed area ,removed by the macrophages + necrotic tissues >>(pus). Phagocytosis 2- Eosinophils 2-6 % Life span : 6 hours. Functions: 1- Kill parasites. 2- Role in Allergy. 3- Produce substances that dissolve blood clots ( plasminogen) 4- weak phagocytic activity. 3- Basophils 0-1%. Life span : 6 hours. Functions : 1- They secrete Histamine and leukotrienes (increase capillary permeability). 2- Secrete Heparin. AGRANULAR LEUKOCYTES 1- Monocytes 2-8 % Life span : 72 hours They become tissue macrophages. They migrate after neutrophils, they phagocytose the dead neutrophils ,dead bacteria and necrotic tissues 2- Lymphocytes 20-30 % Formed in lymph nodes , spleen, thymus Life span : days – months. Function: Specific immune response. T cells: attack invading viruses, cancer cells and transplanted tissue cells. B cells: develop into plasma cell, which secrete antibodies. Nature killer cells: attack a wide verity of pathogens and cancer cells
