Biomed Module 6 obj. 8-9

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Biomed Module 6 obj. 8-9
2012-11-03 17:14:00
Biomed Module obj

Biomed module 6 obj. 8-9
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  1. What is a pathogen?
    An organism that leads to infection or disease in the host.
  2. __________ often results in disease in the host.
  3. ___________ depends on the organism's ability to invade the host, multiply, and avoid ________ from the hosts ________. 
    Pathogenicity, damage, defenses
  4. Virulence
    • a term used to describe the intensity of bacterial and other microbial infections.
    • Varies greatly among different organisms, but is always a factor in infection.
    • Specific pathogenic mechanisms are contributors to virulence
  5. What are the specific pathogenic mechanisms of bacteria?
    • 1. Adherence
    • 2. Colonization
    • 3. Formation of a capsule
  6. Adherence
    • Bacteria use their pulu to cling to the surface of the host cells
    • multiply and form colonies.
  7. Colonization
    • Once in place within the jhost tissue, bacteria replication forms colonies and may overcome the hosts defenses.
    • Colonization by small numbers of non-invasive organisms is normal in all animals including humans.
  8. Formation f a capsule
    In certian pathogens the capul contributes to the organisms virulence because this thick, polysaccharide structure helps organisms resist host defense processes.
  9. _________is the abiltiy of organisms to penetrate host tissue , usually via special ________.
    Invasiveness, enzymes
  10. What are the enzymes tht contribute to invasiveness ?
    • Hyaluronidase
    • Coagulase
    • Steptokinase and staphylokinase
  11. Hyaluronidase
    • Known as the spreading factor
    • produceced by streptococci, staphylococci, and some other pathogens 
    • Attacks hyaluronic acid, the ground substance or connective tissue. 
  12. Coagulase 
    • An enzyme produced by some bacteria that accelerates the clotting of blood 
    • Breaks down collagen, the framework of muscles
  13. Streptokinase and staphylokinase
    • Kinase enxymes digest fibrin and prevent the clotting of blood
    • this results in reduciton of fibrin allowing more rapid difusion of the infectious bacteria in the host tissue
    • exampel : streptococus stain of  "flesh eating bacteria"
  14. What are the types of toxins produces by bacteria?
    • Exotoxins
    • Endotoxins
  15. Exotoxins
    • Very powerfl toxins secreted by the living bacterial cell
    • Mostly from gram positive organisms
    • Gram positive examples: botulism, gas gangrene, tetanus, staphylococcal food poisoning
    • Gram negative exotixin: E. coli 
  16. Endotoxins
    • Found primarily in gram negativ bacteria
    • Are releases only when the oragnism (bacteria) dies.
    • Cause non-specific gastrointestinal symptoms such as diarrhea, cramping, and generalized malaise
    • Examples: cholera, salmonella
  17. True or False: Endotoxins may cause the death of many organisms, leading to anaphylactic shock syndrome, when given doses of antibiotics.
  18. When conditions become unfavorable, bacteria form _________ which is a ______ form.
    Endospores, dormant
  19. Endospores have __________ cell walls to withstand ______________ _______ such as drying and lack f nutritional sources. 
    thickened, environmental extremes
  20. True or False:  Once conditions become favorable endospores revert to vegetative (active) cells and regrowth processes can begin
  21. Endospores 
    • Dormant stage of some bacteria
    • Form when nutritional and enviornmental conditions are unfavorable for growth.
    • Survival under harsh conditions- excessive cold, heat, or dryness
    • Revert to acive cells under favorable conditions
    • Important bacteria that form endospoeres include the clostridiums that cause disease when endospores germinate in the human host.
    • Clostridia species that cause tetanus, botulism, and gas gangrene form endospores.