Chapter 2

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Chapter 2
2013-05-09 18:38:06

Exam 1
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  1. Pathogen
    • Can cause disease in a susceptible host
    • yersinia pestis, bacilus anthracis
  2. Opportunistic pathogens
    • Can cause disease only if a significant change occurs in host resistance
    • Can be part of normal flora
  3. Latrogenic infection
    • Result of mediical treatmentĀ 
    • Catheter,antibiotics,immunosuppressive drugs
  4. Virulence
    Relative ability of a microorganism to cause disease or degree of pathogenicity
  5. Virulance is measured by?
    The number of microorganisms neccessary to cause infection in the host
  6. FDoes virulance correlate with disease?
    Not neccessarily
  7. Virulance factors
    Capsules, toxins, enzymes, cell wall receptors, pili
  8. The bodies defense mechanisms and barriers are
    • Skin
    • Mucus
    • Ciliated epithelial cells
    • Secretions containing antibacterial substances
  9. Specialized cells of mucous membrane are
    • Mucosal cells
    • Goblet cells
    • Mucosa-associated lymphoid tissue
  10. Function of mucus is
    • Trap bacteria before it reaches the outer surface of the cells
    • Lubricates the cells preventing damageĀ 
    • Contains numerous specific and nonspecific antibacterial substances
  11. Location of ucosa-associated lymphoid tissue
    Below the outer cell layer
  12. Function of mucosa-associated lymphoid tissue
    Mediates specific responces against bacteria that penetrate the outer layer
  13. Different types of host resistant factors
    • Physical barriers
    • Cleansing mechanisms
    • Antimicrobil substances
    • Indigenous microbial flora
  14. Forms of cleansing mechanisms
    • Cell shedding
    • fluid in eye, respiratory,digestive,urinary,genital tracts
  15. OForms of antimicrobial substances
    • HCI in stomach
    • Secretory IgA/antibodies
    • Lysozyme
    • B-lysins
  16. Adhesins def.
    Bind specific receptors on the tissue surface, which keeps them from being washed away
  17. Adherins are present
    At the tis of fimbrae and bind tightly to specific carbohydrates on the target tissues
  18. Biofilm
    • Special bac. adaptation that facilitates colonization
    • Often occur in sergical appliances (artificial valves,indwelling catheters)
  19. Toxins def
    Bacterial prducts that directly harm tissue or trigger destructive biologival activity
  20. Endotoxin
    • Part cell wall
    • Gram-postitive
    • Damaging response mediated by host immune system
    • Lipid A portion of LPS is released and acts as a direct endotoxin
  21. Exotoxins
    • Gram-positive & gram-negative
    • Include cytolyic enzymes and receptor binding proteins that alterfunction or kill cell
    • A-B toxis
  22. Superantigens
    • Endotoxins
    • Activate T cells by binding to T-cell receptor and MHC mlc. at the same time
    • Does not require antigen
  23. Superantigens can trigger
    Life-threating autoimmune-like responses
  24. Different infectious agent factors are
    • Adherence
    • Proliferation
    • Tissue damage
    • Invasion
    • Dissemination
  25. Adherence
    • Infectious agent factor
    • In most diseases bacteria must adhere to host cell to initate infection
  26. Proliferation
    • Infectous agent factor
    • Bacteria have to overcome host factors- IgA protease, capsules
  27. Tissue damage
    • Infectious agent factor
    • Exotoxins or endotoxins
  28. Invasion
    • Infectious agent factors
    • Penetrating and growing in tissues
  29. Dissemination
    • Infectious agent factors
    • Spread of organisms to distant sites via blood or lymph
  30. Capsules are made of
    • Polysaccharides (poor immunogens)
    • or
    • Substances that mimic human tissues, no immune response is induced
    • slimmy texture makes hard grasp by phagocytes
  31. Bacteria can evade antibody rsponses by
    • Intracellular growth
    • Antigentic variation
    • Inactivation of antibody or complement
  32. host resitance factors are
    • phagocytosis
    • Inflamation
    • immune responces
  33. phagocytosis consists of what kind of material
    polymorphonuclear nut