Module 4 L5 Flashcards
Skin characteristics
dense keratinized layer, low ph 5.5, fatty acids inhibit microbial growth
Common routes of infection
respiratory, intestinal, urogenital
Bacteria breaks defenses by
releasing enterotoxins, invade and damage internal mucosa
virus breaks defenses by
nonenveloped ones are resistant to bile and digestive enzymes
Fungi break defenses by
in immunocompromised hosts
Intestinal protozoan break defenses by
relying on cysts for transmission
intestinal helminthes break defenses by
causing obstruction of the gut
How pathogens are disseminated
vertical transmission - HBV, CMV, treponema pallidum
4 mechanisms microbes evade immune defense
remain inaccessible, change antigenic repertoires, inactivate antibodies or complement resisting phagocytosis, suppress host adaptive immune esponse
Intestinal tract defenses
acidic gastric ph, mucus, pancreatic enzymes, bile detergents, defensins, IgA, normal gut flora
Urogenital tract defenses
frequent urination, low pH in vagina from catabolism of glycogen in normal epithelium by commensal lactobacilli
How pathogens break defenses in urogenital tract
antibiotics kill lactobacilli and make vagina susceptible to infection
Changing antigenic repertoires
flu, rhinovirus cold, HIV
HIV viral entry
gp120 binds to CD4 and to CXCR4 or CCR5
Rhinovirus viral entry
bind to ICAM-1
SarsCOV2 viral entry
spike protein/ACE2 receptor
Virus encoding proteins that inhibit apoptosis
homogloues of the cellular BCL-2
Major component of cell wall gram negative bacteria
Bacterial endotoxin lipopolysaccharide
Diptheria inhibits protein synthesis by
disulfide bind reduced and broken into the cytoplasm releasing amino fragment A catalyzing transfer of ADP from NAD to EF2 and inactivates it
1 toxin molecule can kill a cell by ADP
ribosylating more than 10^6 molecules
