7. Immune System post

7. Immune System post - The Immune System Chapter 43...

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The Immune System Chapter 43
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Introduction Defense against viruses, bacteria, pathogens, and rogue cells Types of defense Innate immunity Acquired immunity
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Innate Immunity Present before any exposure to pathogens (birth) Nonspecific Components External defenses Internal cellular defenses
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External Defenses Skin cannot normally be penetrated by viruses or bacteria Small abrasions can make vulnerable Mucous membranes that line many internal cavities also act as barriers Mucus traps microbes and they are removed Mucus (and secretions from the skin) also represent unfavorable environments for microbes to grow Skin has a pH 3 to 5 due to sebaceous and sweat glands Stomach has a pH of 2 Secretions from the skin and mucus often contain antimicrobial proteins Lysozyme digests the walls of many bacteria
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Internal Cellular and Chemical Defenses Phagocytic cells Cells that ingest invading microorganisms Also contain other chemicals to limit the spread of pathogen Antimicrobial proteins Chemical signals to initiate the inflammatory process Natural killer (NK) cells Recognize cells that are infected with viruses or are cancerous Once attached to damaged cell NK cells release chemicals that initiate apoptosis
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Phagocytosis Phagocytes attach to their target via surface receptors that recognize “non-self” For example, some sugar groups of bacteria Phagocyte then engulfs the target A vacuole forms that fuses with lysosomes Toxic forms of oxygen (NO) poison microbes Hydrolytic enzymes
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Phagocytic Cells White blood cells called leukocytes Neutrophils Most abundant (60 – 70%) Attracted to infected area by chemotaxis Self-destruct in phagocytosis process (life span 1 – 2 days) Macrophage (monocytes in blood) Fixed and wandering
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This note was uploaded on 04/17/2008 for the course BIOL 112 taught by Professor Maze during the Spring '08 term at Lander.

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7. Immune System post - The Immune System Chapter 43...

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