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Lecture 19, Ch. 43 - Lecture#19 Date Chapter 43 ~ The...

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Lecture #19 Date _________ Chapter 43 ~ The Body’s Defenses
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Lines of Defense Nonspecific Defense Mechanisms……
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Phagocytic and Natural Killer Cells Neutrophils 60-70% WBCs; engulf and destroy microbes at infected tissue Monocytes 5% WBCs; develop into…. Macrophages enzymatically destroy microbes Eosinophils 1.5% WBCs; destroy large parasitic invaders (blood flukes) Natural killer (NK) cells destroy virus-infected body cells & abnormal cells
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The Inflammatory Response 1- Tissue injury; release of chemical signals~ • histamine (basophils/mast cells): causes Step 2... • prostaglandins: increases blood flow & vessel permeability 2/3- Dilation and increased permeability of capillary~ • chemokines: secreted by blood vessel endothelial cells mediates phagocytotic migration of WBCs 4- Phagocytosis of pathogens~ • fever & pyrogens: leukocyte-released molecules increase body temperature
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Specific Immunity Lymphocyctes •pluripotent stem cells... • B Cells (bone marrow) • T Cells (thymus) Antigen: a foreign molecule that elicits a response by lymphocytes (virus, bacteria, fungus, protozoa, parasitic worms) Antibodies: antigen-binding immunoglobulin, produced by B cells Antigen receptors: plasma membrane receptors on b and T cells
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Clonal selection Effector cells: short-lived cells that combat the antigen Memory cells: long-lived cells that bear receptors for the antigen Clonal selection: antigen-driven cloning of lymphocytes “Each antigen, by binding to specific receptors, selectively activates a tiny fraction of cells from the body’s diverse pool of lymphocytes; this relatively small number of selected cells gives rise to clones of thousands of cells, all specific for and dedicated to eliminating the antigen.”
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