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Unformatted text preview: Second Line of Defense: Internal Defenses *internal antimicrobial proteins *phagocytes *Natural Killer Cells *inflammation *fever Antimicrobial proteins-interferons, complement & transferrins Interferons (IFNs)-proteins produced in lymphocytes, macrophages, & fibroblasts-induce synthesis of antiviral proteins that interfere with viral replication-Do not prevent viruses from attaching to hosts, but do stop replication Complement system-“complement” or enhance certain immune responses Transferrins-inhibit the growth of certain bacteria by reducing the amount of available iron Natural Killer Cells (NK cells)-make up about 5-10% of lymphocytes-present in spleen, lymph nodes & red bone marrow-ability to kill a wide variety of infected body cells and certain tumor cells by attacking any body cells that display abnormal or unusual plasma membrane cells-binding of NK cells to a target cell= release of granules containing toxic substances from the NK cells Perforin- protein that inserts into the plasma membrane of the target cell and creates channels (perforations), in which extracellular fluid flows into the target cell and the cell bursts (cytolysis) Granzymes- released by NK cells, protein-digesting enzymes that induce the target cell to undergo apoptosis, or self destruction; microbes released can be destroyed by phagocytes Phagocytes- cells that perform phagocytosis- ingestion of microbes or other particles such as cellular debris; innate defense mechanism 2 major types of phagocytes- neutrophils & macrophages *Wandering microphages-migrate to infected areas *Fixed microphages- stand guard in specific tissues Phases of Phagocytosis: 1. chemotaxis 2. adherence 3. ingestion 4. digestion 5. killing inflammation- a nonspecific, defensive response of the body to tissue damage vasodilation- increase in diameter of arterioles; allows more blood to flow thru the damages area & helps remove microbial toxins and dead cells substances that contribute to vasodilation, increased permeability and other aspects of inflammatory response are: *histamine *kinins *prostaglandins *leukotrienes *complement Specific Defenses against Disease involve the production of a specific lymphocyte or antibody against a specific antigen *immunity or specific resistance- ability of the body to defend itself against specific invading pathogens and foreign tissues Antigens- substances that are recognized as foreign and provoke immune responses; may be microbes, tissues, certain foods, drugs or pollen *Epitope- antigenic determinant; can illicit an immune response *Hapten- too small to illicit immune response; will bind to protein *MHC- major histocompatibility complex *self antigens...
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This note was uploaded on 05/02/2008 for the course BMSP 2135 taught by Professor Tlgillian during the Fall '07 term at Virginia Tech.
- Fall '07