Immunity and the GI Tract

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USMLE Step 1 Medicine Karteikarten am Immunity and the GI Tract, erstellt von Genesis James am 25/09/2019.
Genesis James
Karteikarten von Genesis James, aktualisiert more than 1 year ago
Genesis James
Erstellt von Genesis James vor etwa 5 Jahre
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Zusammenfassung der Ressource

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Microfold (M) cells function in luminal antigen sampling by transporting luminal substances across epithelium to underlying APCs - utilized by salmonella and shigella as a route of invasion through mucosal barrier
Paneth cells - defensin production (poke holes in pathogens to lyse them
Peyer's Patches enriched in lymphoid tissue: - key sites for coordinating immune responses to pathogens - promote tolerance to harmless microbes and food - contain M cells
Neutralization of microbes in the lumen is done by... ...secretory IgA and IgM in the lamina propria
Antibiotic peptides kill pathogens or reduce their entry into epithelium
intraepithelial lymphocytes (IELs) - innate lymphocytes and memory T cells - eliminate infected and damaged cells - help shape subsequent adaptive immune responses
lamina propria lymphocytes (LPLs) - memory T cells : B cells = 4:1 - NK and plasma cells - IL-22 from Th17 cells helps maintain epithelial cell barrier - plasma cells secrete IgA
intestinal dendritic cells - project dendrites between epithelial cells for antigen sampling - process and present antigens from microbes
serum IgA circulates as a monomer in the serum (very little)
secretory IgA - dimer with J chain found in fluids - secretory chain makes it more resistant to proteolytic cleavage by enzymes found in external body fluids - does not activate complement (IgG or pentameric IgM) - prevents binding of pathogens to host cells
Rotavirus symtpoms - destruction of absorptive enterocytes by inducing apoptosis - virus-induced down-regulation of expression of absorptive enzymes
rotavirus immunity IFN-g and IgA
attenuated vaccine (sabin vaccine against polio) - virulent pathogen introduced into non-virulent host - pathogen learns how to survive in a non-human host, so it loses it virulence factors in humans - when introduced into human hosts, Abs are produced against pathogen without it causing harm - only one booster needed - humoral and cell-mediated immunity - HOWEVER, pathogen can revert back to virulent form
killed vaccine (silk vaccine against polio) - virus is killed via chemicals or radiation with g-rays - multiple boosters needed due to inefficient mimicking of original virus OR different route of transmission - mainly humoral immunity - CANNOT revert back to virulent form
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