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2012-12-04 14:34:13
prescott microbiology chapter 31

chapter 31 notes from prescott's microbiology
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  1. Symbiosis
    2 organisms living together in varoious relationships
  2. commensalism vs mutualism vs parasitism
    • one benefits, neither harmed
    • both benefit
    • one benefits, other harmed
  3. final host
    host where parasite gains sexual maturity
  4. reservoir host
    organism infected with a parasite that also infects humans
  5. pathogen
    any parasitic organism that causes infectious disease
  6. primary vs opportunistic pathogen
    • primary causes disease by direct interaction with healthy host
    • opportunistic is part of normal flora and caueses disease when it gains access to a place it shoudn't be 
  7. pathogenicity 
    ability of a parasite to cause disease
  8. immunopathology 
    ability to trigger exaggerated immune responses
  9. factors impacting host parasite relationships
    • # of organisms
    • degree of virulence of pathogen
    • host's defense
  10. the intensity of a pathogen is deteremined by
    • infectivity- ability to esablish focal point of infection
    • invasiveness - ability to spread to adjacent tissues
    • pathogenic potential - degree to which pathogen can damage host
  11. LD50 and ID50
    • number of pathogens that kill 50% of a group of hosts in a specified time
    • same but infect not kill
  12. how to bacterial pathogens gain acess to host
    actively penetrate host's mucous membranes or skin or passivly penetrate through wounds or opening in skin
  13. how to bacteria spread through tissue
    producing specific products or enzymes
  14. bacteremia
    viable bacteria in blood
  15. septicemia 
    bacteria or their toxins in blood
  16. intracellular pathogens
    bacteria that are able to grow and multiply in various cells of a host
  17. facultative intracellular pathogens
    can live within host cells and in the outside environment
  18. obligate intracellular pathogens
    can't grow/multiply outside of a host
  19. pathogenicity islands
    increase virulence is coded in large segments of DNA that carry virulence genes which alllows for things like e. coli to inject virulence proteins into cytoplasm of eucaryotics hosts
  20. intoxications
    disease that result from a specific toxin produced by bacteria
  21. toxemia
    condition caused by toxins in the blood of host
  22. toxin 
    specific substance that damages host
  23. exotoxins
    • usually released as the pathogen grows
    • a soluble protein
    • travels to other tissues to where it causes damge
    • cause antibody produciton (can be bad_
  24. AB exotoxins
    • A subunit is repsonsible for toxic effect
    • B subunit binds to target cell
  25. superantigens
    produce and extrmeem immune respononse from the host
  26. interotoxins: 
    target intestinal mucosa
  27. cytotoxins
    target generall tissues
  28. pore forming exotoxins
    membrane distrupting exotoxin that can cause hemolytic reactions and kill the cell
  29. beta and alpha hemolysis
    beta is complete lysis and alpha is partial
  30. phospholipase enzymes
    remove charged head groups from phospholipids in host cell plasma membranes which destabilizes the membrane so the cell lyses and dies
  31. endotoxins
    • toxins bound to bacterium
    • released when organism lyses
    • lipid A toxic component
    • weaker than exotoxins
  32. systematic effects of endotoxins
    • fever
    • shock
    • blood cogulations
    • weakness
    • diarrhea
    • (all effects are indirect)
  33. host primary defenses
    • limiting bacteria entry while still remaining functional
    • i.e. skin, mucocus membranes with cillia, ph reg
  34. secondary defenses for host
    • soluble anti-microbial producst
    • host blood and other body fluids contain anti-microbials
  35. counter attacks by bacteria
    • have mechanisms to resist:
    • complement system
    • phagocytosis
    • specific immune responses