VCU BIOL 209 - Exam 4 study guide (2 pages)

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Exam 4 study guide

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Exam 4 study guide


Ch. 13, 16, 18-21, 23, 25

Study Guide
Virginia Commonwealth University
Biol 209 - Medical Microbiology
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BIOL 209 1st Edition Exam 4 Study Guide What advantage does a pathogen gain by having a structure which is similar to a host cell structure Molecular mimicry pathogens take advantage of the fact that lymphocytes don t recognize certain types of structures on or in our cells because self reactive T and B cells have been deleted killed or inactivated during development The pathogens resemble these structures and therefore are not recognized by the lymphocytes either Explain how pathogen infection can be related to autoimmunity Autoimmunity occurs when the immune system recognizes and attacks host tissue Pathogens can either initiate or exacerbate autoimmunity by stimulating activation of these lymphocytes Rheumatic fever and Diabetes Type I are examples of immunopathology associated with pathogen infection Compare and contrast inflammation at a site of infection sepsis and anaphylaxis Inflammation at the site of infection brings additional immune mediators to a localized site of infection Bacterial sepsis is a system wide infection that causes a systemic inflammatory response Inflammatory cytokines act on vessels throughout the body leading to loss of blood volume Anaphylaxis is the loss of blood vessel integrity with induced airway muscle contraction It is caused by a systemic release of cytotoxic and inflammatory mediators by tissue mast cells when surface bound IgE is aggregated Describe the immune response mechanism that leads to allergic symptoms How is anaphylaxis related to allergy An allergy is a strong immune response directed to otherwise innocuous but abundant substances such as pollen foods and drugs A general release of histamine causes systemic anaphylaxis Describe primary opportunistic zoonotic and obligate pathogens Primary pathogens cause disease as a result of their presence or activity within a normal healthy host Opportunistic pathogens take advantage of deficient immune systems but do not usually cause disease in a healthy host Zoonotic pathogens can cause disease in both humans and animals Obligate pathogens require a host to survive Distinguish biological vectors physical vectors and vehicles A physical vector is an organism that does not cause disease itself but which spreads infection by conveying pathogens from one host to another Biological vectors are infected with a disease and can transfer their pathogen disease to other organisms A vehicle is a DNA molecule used to transfer an insterted DNA segment into a host cell Explain the function of different types of virulence factors likely to be present in a pathogen that grows on a body surface The capability of surviving with oxygen is a virulence factor necessary for pathogens living on body surfaces These pathogens must also be capable of adhesion Describe different mechanisms that pathogens use for adherence and identify the pathogen structures involved Capsules and biofilms use non specific adhesion of bacterial glycocalyx to host cell surfaces Specific bacterial fimbrae bind to host cell surfaces Fimbrae can mediate pathogen adhesion to specific cell types Adhesion can also involve other structures such as flagella LPS or Lipotechoic acid Spikes are specific viral coat proteins bind to host receptors Describe different categories of secreted virulence factors and identify a mechanism of secretion and targets of individual factors Explain which factors could enhance pathogen invasion and which could inactivate immune responses The Type III System of bacteria can inject factors directly into host cells Injected factors can change the host cell cytoskeleton first enhancing adherence then leading to internalization Some pathogens secrete hyaluronidase which can break down hyaluronic acid a component of the extracellular matrix that forms part of the epithelial barrier Fibrinolytic enzymes help break up blood clots induced by inflammatory processes and promote the spread of infection Describe the different categories of toxins Distinguish between exo and endotoxins enterotoxin and neurotoxins Explain why activation of T lymphocytes by superantigens doesn t promote immunity Exotoxins are secreted from a pathogen either as single molecules or A B toxins Endotoxins are released primarily upon pathogen lysis and break down products of gram negative pathogens Enterotoxins affect cell function of intestinal epithelial cells Super antigens alter the function of a cell stimulating killing T cells to produce cytokines Super antigens induce massive production of cytokines which can eventually kill T cells Identify immune functions that target pathogens that grow outside of host cells Describe different types of evasion mechanisms that pathogens use to resist these immune functions and explain why they are effective Exozymes damage host tissue and allow pathogen invasion outside of cells Evasion mechanisms include encapsulation which inhibits phagocytosis antigenically diverse species that are targets of antibodies and capsule and surface proteins that mimic host structures to hide from adaptive immune systems

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