Micro Exam 4 Test Questions – Flashcards
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| resident biota |
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| (germ free in utero) begins colonizing human host at birth |
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| symbiosis |
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| mutualism, parasitism, commensalism |
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| mutualism |
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| both cells benefit (cows, termites, lichen) |
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| commensalism |
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| one cell benefits and one is unaffected |
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| parasitism |
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| one benefits at the expense of the other |
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| resident biota are found where on the human body? |
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| skin, eyes, nose, mouth, intestinal tract, vagina, urethra |
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| virulence |
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| the degree of ability of a microbe to cause disease in another organism |
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| infection |
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| the colonization of an organism by a mircroorganism - with or without disease |
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| virulence factors |
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| microbial componets that contribute to the ability to cause disease in a susceptible host |
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| pathogen |
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| an organsim capable of causing disease |
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| stages of infection |
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| 1. portal of entry 2. attachment 3. survive hose defense 4. causing damage (virulence factor) 5. exit |
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| becoming established: step one - portals of entry |
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| skin, mucus membranes, GI tract, respiratory tract, urogenital tract |
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| becoming established: step two - attachment |
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| adehesion via fimbriae, capsules, surface proteins, or viral spikes |
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| becoming established: step three - surviving host defenses |
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| avoiding phagocytosis avoiding death inside phagocyte |
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| established: step four - virulence factors, causing damage |
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| enzymes that digest tissues, toxins that damage host cells |
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| exiting: step five |
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| site of release from one host to infect another host (exit is often the same as the portal of entry) |
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| transmission of disease |
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| direct indirect |
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| types of direct transmission |
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| direct contact vertical contact droplet transmission vector transmission |
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| types of indirect contact |
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| fomites(inanimate objects) soil water food aerosols (air) |
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| endotoxins |
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| a toxin that is not actively secreted but is shed from the outer membrane |
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| exotoxin |
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| a toxin molecule secreted by a living bacterial cell into the infected tissues |
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| biological vectors |
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| vector is infected EX: mosquito w/ malaria |
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| mechanical vectors |
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| passive carriers pathogens external EX: flies can transmit cholera by landing on feces then landing on food or a drinking glass |
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| reservoirs of infection |
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| human reservoirs - carriers or people with disease zoonoses - animal diseases that can be transmitted to people non living - soil and water |
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| nosocomial infection |
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| hospital acquired infection |
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| koch's postulates |
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| find evidence of a particular microbe in every case of the disease isolate and culture inoculate a healthy subject and observe reisolate the agent from the experimentally infected subject |
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| resistance |
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| ability to ward off disease, and susceptibility |
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| barriers: first line of defense |
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| physical barriers chemical barriers genetic barriers |
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| physical barrier |
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| skin and mucous membranes mucouse traps and removes many microorganisms, while tears, saliva, urine, and vaginal secretions wash microorgansims from their respective surfaces |
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| chemical defenses (secretions) |
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| lysozyme sebum dnase and rnase sodium chloride gastric juice chelators |
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| lysozyme |
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| hydrolyzes peptidoglycan so it is especially effective against gram positice bacteria, found in saliva, tears, and skin secretion |
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| sebum |
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| unsaturated fatty acids, it inhibits the growth of some bacteria and fungi on skin |
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| DNase RNase |
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| found on the skin |
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| sodium chloride |
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| found in sweat |
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| gastric juice |
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| HCL, proteases (trypsin, pepsin, etc) found in the digestive tract |
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| chelators |
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| found principally in the circulation hemoglobin lactoferrin transferrin |
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| second line of defense |
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| interferon complement phagocytic cells inflammation fever |
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| interferon |
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| produced during viral infection helps host cells inhibit virus reproduction. |
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| where are interferons secreted from |
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| barious cells to signal nearby cells to produce antiviral proteins to degrade viral RNA or block synthesis of viral proteins |
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| complement |
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| a complex array of proteins that funcction via a cascade of enzymatic reactions leading to the formation of a membrane attack complex that forms holes in lipid bilayers of cells or enveloped viruses it also results in chmotaxis of phagocytec cells and enhances phagocytiosis |
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| opsonization |
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| the process of stimulating phagocytosis by affixing molecules to the surfaces of foreign cells or paricles |
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| phagocytic cells |
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| neutrophils, monocytes, macrophages, and dendritic cells which phagocytize and kill invading cells. respond to extracellular invaders |
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| inflammation |
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| initially vasoconstriction to prevent blood loss followed by vasodilation for increased blood supply, increased permeability resultiln in edema, and the movement of phagocytic cells into the infected site from the blood vessels - these serve to wall off the area of injury and to kill the invading pathogen. |
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| fever |
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| elevated host body temp interleukin 1 (exogenous pyrogens) limits iron availability inhibits bacterial growth interferes with viral replication increases effectiveness of some immune molecules |
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| characteristics of the specific immune response |
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| discriminates self from non self specific memory T and B cells primed to respond primary and scondary responses |
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| discriminates self from non self |
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| utilizes histocompatability antigens (MHC and HLA) |
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| specific |
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| reacts only against the antigen which elicited teh response |
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| anamnestic response |
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| in immunology, an augmented response or memory related to a prior simulation of the immune system by antigen, it boosts the levels of immune substances |
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| steps in acquired immunity |
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| development of lymphocytes antigen presentation lymphocyte challenge immune response T and B reponses |
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| development and differentiation |
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| genetic recombination during embryonic and fetal development produce billions of unique lymphocytes each with a different receptor. |
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| self tolerance |
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| elimination of cells which would react with the body's own tissues. |
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| presentation of antigen |
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| APC(antigen presenting cells=dendritic cells or macrophages) present antigen |
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| lymphocyte challenge |
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| proliferation and differentiation occurs in B and T cells in response to challenge with immunogen usually with assistance from a T helper cell. |
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| antigen receptors |
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| antigen receptors on B cells are Ig molecules, while antigen receptors on T cells are unrelated glycoproteins |
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| humoral immunity |
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| A B cell in response to a specific antigen, with the help of a T-helper cell, undergoes clonal expansion and differentiates into memory B cells and plasma cells. memory cells are long lived and are accailable to respond upon re-exposure to the same antigen. plasma cells are short lived and secrete antibody molecules |
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| five classes of antibody |
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| IgG - most common in blood IgM - first class of antibody produced in response to antigen IgA - secretory antibody found in the secretions on the surface of mucus membranes IgE - responsible for allergic responses IgD - no known function |
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| antigen-antibody reactions include |
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| opsonizaation, neutralization, agglutination, and complement fixation |
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| opsonizaiton |
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| the process of stimulation phagocytosis by affixing molecules to the surfaces of foreign cells or particles |
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| neutralization |
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| the process of combining an acid and a base until they reach a balanced proportion, with a pH value close to 7 |
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| agglutination |
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| the aggregation by antibodies of suspended cells or similar-size particles into clumps that settle |
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| cellular immunity |
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| A T cell in response to a specific antigen, with the help of an antigen presenting cell and a T-helper cell, undergoes clonal expansion and differentiates into memory T cells and effector T cells. |
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| effector T cells |
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| cytotoxic T cells (CD8) helper T cells (CD4) |
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| cellular immunity is carried out by what? |
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| cytotoxic T cells that recognize and kill infected cells, tumors, and cancers. |
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| four types of acquired immunity |
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| natural active - exposed to antigen natural passive - exposed to antibody artificial active - injected with antigen artificial passive - injected with antibody |
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| types of allergic reactions |
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| type I immediate type II cytotoxic type III immune complex type IV delayed type V autoimmunity |
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| type I allergic reactions: atopy anaphylaxis |
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| IgE reactions to allergens atopy - local reaction such as hay fever or asthma anaphylaxis - systemic, potenntially fatal reaction involving airway obstruction and circulatory collapse |
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| type II hypersensitivities: reactions that lyse foreign cells |
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| IgM and IgG plus complement reaction to cell surface antigens Ex: ABO antigens and lood transfusion reactions Ex: Rh factor and hemolytic disease of newborn |
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| type III hypersensitivities: immune complex reactions |
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| IgG and IgM plus complement reaction to soluble antigens arthus reaction - a localized reaction to repeated injection of vaccines serum sickness - immune complexes that result in inflammation responses in blood bessels, heart or lungs, joints, skin, or kidney |
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| type IV hypersensitivities: cell mediated (delayed) reaction |
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| T cell mediated hypersensitivity Ex: contact dermatitis (poison ivy) |
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| type V autoimmunity |
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| loss of self tolerance AIDS |
