Karteikarten
Chapter 15
Karten in diesem Stapel (22)
- 1antigenic variationalter surface proteins, thwarting immune response
- 2coagulasecoagulates fibrinogen.
enables the conversion of fibrinogen to fibrin
as a result of coagulase, WBC's, other body defenses can't reach site of infection - 3hemolysinslyse host's cells by making protein channels in the plasma membrane
- 4hyalurodinasethe enzyme attacks the interstitial cement ("ground substance") of connective tissue by depolymerizing hyaluronic acid, enhancing pathogen penetration through tissues
- 5IgA proteasedestroy IgA antibodies (mucosal antibodies) produced by the host
Neisseria genus - 6kinaseconvert inactive plasminogen to plasmin which digests fibrin and clotting of the blood.
The absence of fibrin in spreading bacterial lesions allow more rapid diffusion of the infectious bacteria - 7leukocidinstoxins which kill phagocytic WBC's (leukocytes)
most are produced by streptococci and staphylococci - 8parenteral routeother micros gain access to body when deposited directly into tissues beneath skin
injection, cut, bite, wound, introduced directly into the body - 9cytopathic effectany detectable changes int he host cell due to infection
example: cell rounding, disorientation, swelling or shrinking, death, detachment from the surface - 10ID50infectious dose for 50% of the test population
the infectious dose is a measure of the likelihood of a host acquiring a disease given exposure to a pathogen - 11LD50Lethal dose (of a toxin) for 50% of the test population
- 12transductionprocess in which infection by a virus results in DNA being transferred from one bacterium to another
- 13identify the most commonly/frequently used portals of entrymucous membrane - respiratory tract
others: GI tract, genitourinary tract, conjunctive, skin, parenteral route - 14identify factors that contribute to the virulence of a host(1) number of microbes that gain access to a host
(2) evasion of host defenses
(3) toxin production - 15identify mechanisms for pathogen adherence to host(1) adhesins (ligands)--bind to receptors on host cells
(2) glycocalyx
(3) fimbriae
(4) M protein - 16what are siderophores and what cells/molecules do they target?iron-binding factors that allow some bacteria to compete with the host for iron (transferrin), hemoglobin (blood cells), ferritin
- 17how would the host counteract this potential threat to its health?By producing a fever which increases the production of transferrin. Tranferrin tightly binds to to iron preventing siderophores from binding to the iron.
- 18identify mechanisms for avoiding host antibodies1. IgA protease cleaves IgA antibodies (Neisseria gonorrhoeae)
2. Antigenic variation to alter surface antigens and allowing bacteria to stay ahead of antibody production (N. gonnorrhoeae)
3. Cover themselves in host - 19distinguish between endotoxins and exotoxins
- 20in d e t a i l, explain how endotoxins can lead to a pyrogenic response as well as septic shock(1) A macrophage ingests a gram negative bacterium. The bacterium is degraded in a vacuole, releasing endotoxins that induce the macrophage to produce cytokines IL-1 and TNF. The cytokines are released into the bloodstream through which they travel to the hypothalamus of the brain. The cytokines induce the hypothalamus to produce prostaglandins, which reset the body's thermostat to a higher tempurature, producing fever.
(2) Cytokine release activates complement + coagulation cascade which leads to sequestration of blood in peripheral vessels --> drastic drop in blood pressure (shock) - 21regarding exotoxins, how can nonpathogenic strains become pathogenic?transduction
- 22identify the purpose of using a Limulus amoebocyte lysate assay in drugs, medical devices, bodily fluidsendotoxin
if endotoxin is present, amoebocytes will lyse, releasing the clotting protein-->precipitate confirms (positive)
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- Karteikarten am Chapter 15, erstellt von newsha am 07/11/2014.
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