Lecture12 - Lecture 15: Immune System Chapter 43 Innate...

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Lecture 15: Immune System Chapter 43
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Innate immunity - rapid response to broad range of microbes Internal defenses phagocytes - white blood cells that ingest microorganisms, produce proteins , initiate inflammatory response natural killer cells - non- phagocytes that attack and kill agent (bacteria, cancer, etc) External defenses skin - several layers of tightly packed cells; relatively dry mucous membranes - secrete mucus trapping invading cells secretions - maintain skin at hostile acidic pH (3-5); also, lysozyme (antimicrobial) secreted in tears, mucus, and saliva
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Innate immunity: phagocytic cells 1. Pseudopodia surround microbes 2. Microbes engulfed 3. Vacuole containing microbes forms 4. Vacuole and lysosome fuse 5. Microbes destroyed 6. Microbial debris released by exocytosis bacteria have evolved mechanisms of avoiding phagocytosis (capsule) and
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Innate immunity: phagocytic cells 1. neutrophils - 60-70% of all WBC; attracted to infected tissues; typical self-destruct during phagocytosis 2. macrophages - 5% of all WBC; develop from monocytes; circulating and resident to some organs (e.g., lymph nodes) 3. eosinophils - low abundance; low phagocytic activity; crucial in defense against multicellular parasites (don’t ingest, but discharge harmful enzymes) 4. dendritic cells - low abundance; can ingest microbes, but primary role is to stimulate development of acquired immunity
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Innate immunity: antimicrobial proteins Lysozyme - destroys bacterial cell walls; e.g., in lysosome- freely floating and localized in lysosome Defensins - group of proteins that damage pathogens, not host cells Interferon - defense against viral infection; alpha and beta secreted by infected cell (neighboring cells produce anti- virals); gamma activates macrophages Complement system - about 30 proteins in blood that are normally inactive; activation trigger by presence of microbe; lead to microbe lysis; some proteins help initiate inflammatory response or acquired immunity
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This note was uploaded on 11/24/2011 for the course BIOLOGY 110 taught by Professor Bentz during the Spring '09 term at Drexel.

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Lecture12 - Lecture 15: Immune System Chapter 43 Innate...

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