BIO 1109 Lecture Notes - Lecture 11: Natural Killer Cell, Interferon, Phagocyte
18 Oct 2015
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Document Summary
Body defends pathogens with 3 lines of defense. 1st and 2nd of defense are innate-don"t need to be activated, already present. -respond the same way to every invader external & internal. The second line of defense includes phagocytic white blood cells, such as macrophages, antimicrobial proteins, and the inflammatory response. 3rd line of defense is adaptive which is activated by exposure to specific invader. Its internal: external innate defense barriers. Intact skin- surface barrier can"t be penetrated a: mucous membrane- produce mucus to trap pathogens-cilia remove it by sweeping action, chemical secretions are antimicrobial enzymes in saliva, sweat, and tears digest bacterial walls. Oils and acids on skin are inhospitable to microbes: a. 2 types of phagocyte engulf and digest pathogens & debris. Natural killer cells (nk cells) attack virus-infected & tumor cells, causing them to burst: defensive proteins. Interferons- produced and released by virus-infected body cells. Bind to receptors on nearby body cells stimulating them to produce antiviral proteins.
