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chapt22_lecture-2 - Immunity Ability to resist damage from...

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22-1 Immunity Ability to resist damage from foreign substances such as microorganisms and harmful chemicals Categories Innate or nonspecific resistance Mechanical mechanisms: prevent entry or remove microbes. Skin, tears, saliva, mucous membranes, mucus. Considered the acid mantle Chemical mediators: promote phagocytosis and inflammation Cells: involved in phagocytosis and production of chemicals Adaptive or specific immunity Specificity: ability to recognize a particular substance Memory: ability to remember previous encounters with a particular substance and respond rapidly
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22-2 Adaptive Immunity Involves the ability to recognize, respond to ( immunocompetence) , and remember a particular substance ( memory) Stimulants Antigens : large molecules Foreign: not produced by body, introduced from outside. Bacteria, viruses, other microorganisms that cause disease Pollen, animal dander, feces of mites, foods, drugs cause overreaction of immune system called allergic reaction. Self-antigens : produced by body. Used as markers to allow adaptive immune response to differentiate self from non-self. Response to self tumor antigens helpful Response to self-antigens resulting in tissue destruction: auto immune diseases Haptens : small molecules, combine with large proteins and producing an adaptive immune response. Types Humoral or Antibody-mediated : B cells Cell-mediated : T cells ( make distinctive proteins inserted in plasma membrane they are antigen receptors and recognize specific antigens ( CD4 or CD8) CD8 are cytotoxic T cells ( cells attacking cells ) CD4 cells become T helper cells and activate cell mediated and antibody activation
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22-3
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22-4 Origin and Development of Lymphocytes Positive selection Ensures survival of lymphocytes that react against antigens. These then proliferate and form clones.
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