Innate Immunity - are circulating precursors to macrophages...

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Innate Immunity If pathogens do gain entry into the body, the body's innate defenses come into play. Neutrophils are multi-talented defenders that destroy invading bacteria by phagocytosis and creating a killing zone. Phagocytosis is relatively slow as neutrophils can only destroy a few bacteria at a time. The respiratory burst creates a toxic environment (a killing zone) in the vicinity and may destroy multiple bacteria at one time. The production of O 2 .- , HClO , and H 2 O 2 by neutrophils destroys nearby cells, including bacteria. Eosinophils are also phagocytes, but they phagocytose antigen- antibody complexes and allergens rather than invading microorganisms. Eosinophils also create killing zones around parasites by releasing digestive and toxic enzymes. Basophils aid the mobility of other WBCs by secreting histamine and heparin . These chemicals result in increased blood flow to the site of infection and aid the movement of WBCs out of the circulatory system and into the tissues. Monocytes
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Unformatted text preview: are circulating precursors to macrophages, which leave the circulatory system and colonize lymph nodes and other tissues. The final type of cell involved in innate immunity are the natural killer cells. Natural killer cells are a sub-class of T-lymphocytes that lyse cancerous host cells or host cells infected with viruses or bacteria by release of perforin proteins. (See Figure 3) Figure 3 Complement System and Inflammation The complement system is a group of blood plasma proteins that are activated by pathogenic invasion. When activated, these proteins either bind to pathogens or antibody-pathogen complexes to target them for destruction by phagocytosis or form a membrane attack complex to lyse the invading cell. (See Figure 4) Figure 4 Inflammation, while painful, is a defensive response to tissue injury that limits the spread of pathogens, removes cellular debris, destroys pathogens, and facilitates tissue repair....
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This note was uploaded on 01/30/2012 for the course BSC BSC1085 taught by Professor Sharonsimpson during the Fall '10 term at Broward College.

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Innate Immunity - are circulating precursors to macrophages...

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