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A@AbtahiRahib

Human body IMMUNOLOGY(part-2)

Topic-Innate immunity And Acquired. ****#Innate (Non-specific)immunity:**** Defination:Innate immunity is the resistance of the body against antigen that exists prior to exposure to the antigen i.e.it is inborn. It is non-specific. **Components of innate immunity:** a) Mechanical/Physical Factors: 1. Anatomical barriers: -Keratin layer of intact skin. -Intact mucous membrane of different organs. -Bony encasements. 2. Mechanical removal: -Mucus and cilia. -Coughing and sneezing reflexes → expel trapped foreign substances. -Vomiting and diarrhoea. -The physical flushing action of body fluids. b)Chemical Factors: 1. Pattern-recognition receptors. 2. Antigen non-specific antimicrobial chemicals: -Low pH of stomach and vagina inhibits growth of many microbes. -Fatty acids of skin inhibit growth of micro-organisms. -Acid pH of sweat and sebaceous secretions Lysozyme in tears, nasal secretions and saliva cell wall. -Spermine and zinc in the semen are bactericidal. -Lactoperoxidase in milk has bactericidal action. 3. Antigen non-specific antimicrobial cytokines. c) Biological Factors (cellular & soluble factors): 1)The complement system: -The lectin complement pathway. -The alternate complement pathway. 2) Cells involved in body defense: -Defense cells in the blood (leucocytes). -inhibitory to microorganisms. -degrades peptidoglycan of bacterial -Defense cells in the tissue (macrophages, dendritic cells, mast cells etc.). -Normal flora can compete with pathogenic bacteria for nutrients and also produce antimicrobial substance.

****#Acquired (Specific) immunity:**** Defination:Acquired immunity is the resistance of the body against antigen that occurs after exposure to an antigen. It improves upon repeated exposure, and is specific. **Components of Acquired immunity** : Antibody Cells: -Basophil, activated T-cell,Macrophage,Eosinophil,Basophil ***I will continue this Topic in my next Acrtile** **

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