external barriers (non specific resistance) |
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defends against invasion of pathogens |
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pathogens |
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disease-producing agents that include infectious organisms, toxic chemicals and radiation |
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human environment for pathogens |
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human body harbors billions of bacteria because homeostasis provides ideal temperature, moisture and PH nutrients for microbial life |
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___________ and ____________ are first line of defense against pathogens |
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skin and mucous membranes |
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skin= |
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too dry and nutrient weak for microbes to survive |
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epidermal cells and keratin |
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provide mechanical mechanical barriers against microbes |
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antimicrobial chemicals and lactic acid |
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come from sweat and form coating over skin |
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sebaceous glands |
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secrete sebum to form protective film over skin |
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mucous membranes |
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line body cavities that are exposed to the exterior, secretes mucous that traps microbes |
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areolar connective tissue |
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contains hyaluronic acid which gives it thick, sticky consistency which make it hard for microbes to penetrate them |
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lacrimal apparatus |
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secrete tears to prevent microbes from infecting eyeballs |
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saliva |
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dilutes the number of microorganisms and washes them from mouth and teeth |
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sweat glands |
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produce perspiration to flush microorganisms from the skin |
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mucous, tears, saliva, and perspiration contain: |
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lysozomes |
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lysozomes |
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dissolve bacterial walls |
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urine |
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prevents bacterial growth in urinary system by constantly flushing the urethra |
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acidic secretions |
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from gastric glands in stomach and in the vagina -stop bacteria growth in intestinal tract and in female reproductive tract |
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organisms that get past the skin and mucous membranes are attacked by _________________ |
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phagocytes |
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neutrophils |
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usually phagocytize bacteria but can also kill bacteria with chemicals |
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killing zone |
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neutrophils release enzyme to form a killing zone around itself |
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neutrophils contain |
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hydrogen peroxide and hypochlorite |
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natural killer (NK) cells |
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are large lympocytes made in red bone marrow which can kill a variety of bacteria
-they also can host cancerous or virus infected cells |
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natural killers release |
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perforins |
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perforins |
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rupture the membranes and destroy target cells |
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macrophages |
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develop from monocytes and become scavenger cells |
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wandering macrophages |
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leave the blood and seek out pathogens |
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fixed macrophages |
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stand guard in tissues and/or organs and phagocytize bacteria that come to them |
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antimicrobial proteins |
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provide second line of defense when pathogen penetrates skin and mucous membranes |
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interferons |
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proteins that are produced and released by cells that are cancerous or infected with viruses
-stimulate uninfected neighboring cells the produce antiviral proteins that will inhibit viral replication
-stimulate phagocytosis and activate NK cells |
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complement system |
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a group of 30 or more proteins made by the liver and circulate in blood plasma in inactive form |
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activation by a pathogen.... |
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splits complement proteins into fragments that can destroy pathogen by inflammation, immune clearance, phagocytosis and cytolysis |
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classical pathway |
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requires activation of antibodies -makes it a part of the immune response |
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alternative pathway |
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non-specific -active complement fragments bind to viruses and bacteria |
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lectin pathway |
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binds plasma proteins to particular carbohydrates to initiate reaction cascade |
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inflammation |
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local response to tissue damaged-designed to limit spread of pathogen, to remove debris associated with damaged tissue -initiate tissue repair |
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characteristics of inflammation |
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redness, swelling, heat and pain |
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words ending in "itis" indicate: |
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inflammation |
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occurence of inflammation |
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can occur anywhere in the body but is most common in the skin |
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mediation of inflammation |
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mediated by cytokine proteins that alter physiology or behavior of the recipient cell |
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local vasodilation |
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increases blood flow to the damaged tissue causing hyperemia |
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hyperemia |
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redness and heat in inflamed region |
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mast cells release |
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histamines, kinins, prostaglandins, and leukotrines |
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histamines, kinins, prostaglandins and leukotines: |
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increase permeability of blood vessels and promote filtration of fluid from blood into interstitial spaces |
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soon after inflammation occurs... |
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damaged tissue is flooded with leukocytes
-leads to increased WBC count (inflammation) |
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when tissue is filled with leukocytes |
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neutrophils cling to the inner walls of the capillaries to signal location of inflammation |
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diapedesis |
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allows leukocytes to change shape and crawl through capillary walls to interstitial fluid |
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pathogens are contained and destroyed before... |
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they can spread throughout the entire body |
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fibrinogen |
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forms clot around the damaged tissue and keeps pathogens out |
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heparin |
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prevents blood from clotting in vicinity of injury |
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chemotaxis |
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site of injury or infection |
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neutrophil are attracted by___________ and begin to ___________________ |
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chemicals that guide them to the chemotaxis; and being to phagocytize and destroy bacteria |
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neutrophils attract __________ and more ______________ by secreting ______________ |
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monocytes; and more neutrophil; by secreting cytokines |
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monocytes |
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arrive 8-12 hours after injury and become wandering macrophages and engulf remaining bacteria, host cells, worn neutrophils and debris |
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monocytes act as |
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antigen presenting cells -activate the immune response |
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pus |
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dead and dying phagocytes, cellular debris, and living and dead pathogens get surrounded by thick yellowish pus
-accumulates in abscess |
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blister |
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pus is usually drained from infection site but if it cannot drain from inflammation site blister may form and may need surgical drainage |
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fever |
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an abnormal elevation of body temperature resulting from trauma or infection |
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fever promotes |
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interferon activity, metabolic rate, inhibits reproduction of bacteria or viruses, and accelerates tissue repair |
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neutrophils and macrophages |
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secrete fever producing agents to raise hypothalamic set point for body temperature |
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neutrophils and macrophages ::: |
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-causes shivering to generate heat and vasoconstriction to reduce heat loss
-temperature oscillates around new-set-point as long as pathogen is present
-when pathogen is finally destroyed secretion of fever-producing agents halt and hypothalamic set point returns to normal
-vasodilation and sweating occur |
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reye syndrome |
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in children under 15, some viral infections are followed by Reye syndrome |
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triggers of reye syndrome |
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aspirin--children shouldn't take aspirin when they have the chicken pox or flu like symptoms |
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