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51 Cards in this Set
- Front
- Back
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Portals of Entry |
- pathogens gain entrance to the human body and other host through several avenues - do not need to penetrate the body - ex: mucous membranes, skin, parenteral route |
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Mucous Membranes |
- many bacteria and viruses gain access to the body by penetrating the mucous membrane lininng - respiratory tract - gastrointestinal tract - genitourinary tract - conjunctive |
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Skin |
- unbroken skin is impentrable by most micooorganisms - gain access through openings in the skin, such as hair follicles, and sweat glands ducts |
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Parental Route |
- punctures, injections, bites, cuts, wounds, surgery, and splitting of skin or mucous membrane due to swelling or dyring can establish parental routes |
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ID50 |
- the virulence of microbe - the number of cells required to cause an infection |
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LD50 |
- potency of a toxen |
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Adherence |
- attachment between pathogen and host at their portal of entry - necessary step in pathogenicity |
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Adhesins or ligands |
- means of surface molecules on pathogen to which they bind specifically to complementary surface receptors on the cells of certain host tissues - may be located on a microbe's glycocalyx or on other microbial surfaces structures, such a pili, fimbriae, and flagella |
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Receptors |
- are usually sugars such as mannose |
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Biofilms |
- Microbes that have the ability to come togetherin masses, cling to surfaces, and take in and share available nutrients - Once they adhere to the surface they multiplyand secrete a glycocalyx that further attaches bacteria to each other and to thesurface - Another method of adherence and resistdisinfectants and antibiotics |
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Capsules |
- Capsules resist the host’s defense by impairingphagocytosis - Strains with capsules are virulent |
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Cell Wall Components |
- Cell walls of certain bacteria contain chemicalsubstances that contribute to virulence |
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M Protein |
- Heat resistance and acid resistant protein - Found on both the cell surface and fimbriae - Mediates attachment of the bacterium toepithelial cells of the host and helps the bacteria resist phagocytosis bywhite blood cells - Increases the virulence of the microorganism |
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Fimbriae |
- Help attach to host cell |
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Opa |
- Out membrane protein - Help attach to host cell |
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Waxy Lipid |
- Mycoclic acid - Increases the virulence by resisting digestionby phagocytes and can even multiply inside phagocytes |
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Enzymes |
- Can digest materials between cells and form ordigest blood clots |
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Coagulases |
- Bacterial enzymes that coagulate the fibrinogenin blood - Convert fibrinogen into fibrin, the threads thatform a blood clot - The fibrin clot may protect the bacterium fromphagocytosis and isolate if from other defenses of the host |
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Kinases |
- Bacterial enzymes that break down fibrin andthus digest clots formed by the body to isolate the infection |
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Hyluronidase |
- An enzyme secreted by certain bacteria - Hydrolyzes hyaluronic acid, a type ofpolysaccharide that holds together certain cells of the body, particularlycells in the connective tissue - Digesting action is thought to be involved inthe tissue blackening of infected wounds to help the microorganism spread fromits initial site of infection |
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Collagenase |
- Another enzymes - Facilitates the spread of gas gangrene - Breaks down collagen which forms the connectivetissue of muscles and other body organs and tissue |
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IgA Proteases |
- Can destroy IgA antibodies |
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Antigenic Variation |
- pathogens can alter thier surface of antigens - unaffected by the antibodies of the host |
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Invasins |
- surface proteins that rearrange nearby actin filament of the cytoskeleton |
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Four Basic Ways to Damage the Cell |
1) by suing the host's nutrients 2) by causing direct damage in the immediate vicinity of the invasion 3) by producing toxin transported by blood and lymph 4) by inducing hypersensitivity reactions |
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Siderophores |
- protein that take the iron away form iron transport protein by binding the iron even more tightly |
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Direct Damage |
- as pathogens metabolize and multiply in the cell the cells usually rupture - some bacteria can penetrate host cells by excreting enzymes and by their own motility - most damage is done by toxins |
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Toxins |
- poisonous substance that are produced by certain microorganisms - contribute to the pathogenic properties - produce fever, cardiovascular disturbances, diarrhea, and shock - can inhibit protein synthesis, destroy blood cells, and blood vessels, and disrupt the nervous system by causing spasm |
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Toxigenicity |
- the capacity of microorganisms to produce toxins |
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Toxemia |
- refers to the presence of toxins in the blood |
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Exotoxins |
- produced inside some bacteria as part of their growth and metabolism and are secreted by the bacterium into the surronding medium or released by lysis - proteins and many are enzymes that catalyze only certain biochemical reactions - small amounts are quite harmful - produce them are gram positive or gram negative bacteria - work by destroying particular parts of the host's cell or by inhibiting certain metabolic functions - exotoxins are disease specific |
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Antitoxins |
- antibodies that provide immunity to exotoxins |
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Toxoids |
- altered exotoxins - occur when exotoxins are inactivated by heat or by formaldehyde, iodine, or other chemical, they no longer cause disease |
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A - B Toxins |
- A part is the active component - B part is the binding component |
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Steps of A - B Toxins |
1) bacterium produces and releases exotoxin 2) B component of exotoxin attaches to the host cell receptor 3) A - B exotoxin enters host cell by receptor mediated endocytosis 4) A - B exotoxin enclosed in pinched off portion of plasma membrane during pinocytosis 5) A - B components of exotoxin separate. The A component alters cell function by inhibiting protein synthesis. The B component is released from the host cell |
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Membrane Disrupting Toxins |
- causes lysis of hsot cells by disrupting thier plasma membrane - do this by forming channels in the plasma membrane - others disrupt the phospholipid portion of the membrane - contribute to virulence by killing host cells, especially phagocytes, and by aiding the escape of bacteria form sac within phagocytes into the host cell's cytoplasm |
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Leukocidins |
- membrane disrupting toxins that kill phagocytic leukocytes - act by forming protein channels - also active against macrophages |
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Hemolysins |
- membrane disrupting toxins that destroy erythrocytes, also by forming protein channels |
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Superantigens |
- atigens that provoke a very itense immune response - bacterial proteins - stimulate the proliferation of immune cells called T cells - T cells are stimulated to release enormous amount of chemicals called cytokines - high levels of cytokinesis give rise to a number of symptoms, including fever, nausea, vomiting, and diarrhea |
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Endotoxins |
- are part of the outer portion of the cell wall of gram negative bacteria - aka lipid A - it is a lipid - released when negative gram bacteria die and their cell undergo lysis - antibiotics causes lysis of gram negative bacteria causing release of endotoxin and may lead to an immediate worsening of symptoms - exert their effects by stimulating macrophages to release cytokines in very high concentrations - all endotoxins produce the same signs and symptoms - activates blood clotting proteins, causing the formation of small blood clots and obstruct capillaries and results in death of tissue - do not promote the formation of effective antitoxins against the carbohydrate component of an endotoxin |
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Endotoxins Pyrogenic Response Steps |
1) a macrophage ingest a gram negative bacterium 2) the bacterium is degraded in a vacuole, releasing endotoxins that induce the macrophage to produce cytokines 3) the cytokines are released into the bloodstream by the macrophages, through which they travel to the hypothalamus of the brain 4) the cytokines induce the hypothalamus to produce prostaglandins, which reset the body's thermostat to a higher temperature ` |
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Shock |
- life- threatening decrease in blood pressure |
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Septic Shock |
- shock caused by bacteria |
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Limulus Amebocyte Lysate |
- labatory test which can detect even minute amounts of endotoxin |
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Lysogenic Conversion |
- host bacterial cell and its progeny may exhibit new properties endcoded by the bacteriophage DNA - bacterial cell is immune to infection by the same type of prophage |
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Cytopathic Effects |
- the visible effects of viral infection - used to diagnose many viral infections |
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Cytocidal Effects |
- cytopathic effects that result in death |
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Inclusion Bodies |
- granules found in the cytoplasm or inculesu of some infected cells - sometimes viral parts, nucleic acids or proteins in the process of being assembled into virions - important because their presence can help identify the virus causing an infection |
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Syncytium |
- large mulitnucleated cell - several adjacent infected cells that fuse together |
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Interferons |
- this protects neighboring cells form viral infections |
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Portals of Exit |
- routes in which microbes leave the body - secretions, excretions, secretions, discharges, or tissue that has been sheed - part of the body that has been affected - most common are respiratory and gastrointestinal tracts |
