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biol 1002 ch 32


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4-1-2008 CHAPTER 32: DEFENSE AGAINST DESEASE: THE IMMUNE SYSTEM Three lines of defense against microbial attack: - Non Specific External barriers 1. Skin, Mucous Membranes (Ex. Castle) Non specific because it keeps EVERYTHING out - Nonspecific Internal Membranes 1. Phagocytic and natural killer cells, Inflammation, Fever - Specific Immune Response 1. Uses antibodies and antibody-like receptors 2. Cell mediated immunity, and Humeral immunity 1. EXTERNAL BARRIERS (skin, mucous membranes) keep everything out (dirt, dust, microbes, etc.) a. Skin 1. Physical barrier to microbial entry 2. Puncture, or cut, is a way to get infection. 3. Inhospitable environment for growth; dry, dead cells at surface. Sweat/sebaceous glands secreting acids and natural antibiotics like lactic acid b. Mucous Membranes of respiratory and digestive tracts well-defined. Secretions have antibacterial enzymes. c. Stomach ; if microbes swallowed, acids and protein-digesting enzymes destroy them. 2. NONSPECIFIC INTERNAL DEFENSE a. PHAGOCYTIC CELLS ; white blood cells (WBC) in extracellular fluid, amoeboid shape, destroy microbes by phagocytosis. b. NATURAL KILLER CELLS : WBC that destroy body cells infected by viruses and cancerous cells by punching HOLES in them. c. INFLAMMATORY RESPONSE , cause by large scale microbial invasion through wound 1. histamine released by damaged cells 1. histamine increases blood flow, makes one bleed, blood is sterile, like it “washes” out wound. 2. This “wash out” leads to inflammation (red, swollen, warm) 3. Other chemicals macrophages (WBC engulf bacteria, dirt, and tissue debris) 4. Blood clotting “walls off” wounded area. Pus is just WBC dying. - Textbook Picture 1. Tissue damage carries bacteria into wound 2. Wounded cells release chemicals that stimulate mast cells 3.
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