THE IMMUNE SYSTEM by d jones Nonspecific Immunity
THE IMMUNE SYSTEM by d jones
Nonspecific Immunity Ü Does not distinguish between infectious organisms
First Line of Defense Ü Skin Barrier Ü Mucous membranes Ü Sweat & sebaceous glands lower the p. H of skin Prevents growth of many microbes Ü Saliva, tears, cilia and mucous wash away microbes Ü Lysozyme and other enzymes digest cell walls In tears and upper portion of respiratory tract Ü Acid in stomach destroys many microbes
Second Line of Defense Ü Phagocytosis Ingestion of invading organisms Monocytes migrate into tissues – Develop into macrophages w Lysozomes digest consumed microbes – Stay in lymph nodes, spleen, tonsils Eosinophils – Excrete enzymes to destroy large parasites Natural killer cells (NK) – Destroy virus infected cells and abnormal cells
Inflammatory response – Precapillary arterioles dilate &Post capillary venuoles constrict – Increases blood supply w Causes redness and heat – Vessel permeability increases w Fluid moves into tissue w Causes swelling – Chemokines are produced w Attract phagocytic cells Consume invaders Clean up damaged tissue – Pus is dead phagocytes and tissue fluid
Fever – Inhibits growth of microorganisms – Speeds body reactions w Helps phagocytes Complement system – Lyse cell membranes – Attract phagocytes Interferons – Secreted by virus infected cells – Cause neighboring cells to produce chemical that inhibit viral replication
SPECIFIC IMMUNITY Ü Responds to specific microbes Ü Lymphocytes B – made and programmed in the bone marrow T – made in bone marrow and programmed in the thymus – MHC(major histocompatibility complexes) are recognized by the T cells w Glucoproteins in cell membranes indicate”self“ cells
Ü Antigen Foreign molecule that causes a response ÜB cells produce antibodies Protein Y shaped Specific based on shape of antigen Membrane has antigen receptors Antibo dy movie
ÜB cell contacts antigen Ü Divides forming clones (clonal selection) Effector cells combat invader – Plasma cells(B cells) & Effector T cells are produced Memory cells to remain in case of later invasion
Primary Immune Response occurs first time body is exposed to an antigen Maximum response takes 10 to 17 days
Secondary Immune Response Occurs on second exposure 2 to 7 day response of larger magnitude that lasts longer
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