uworld missed concepts Flashcards
ventromedial hypothalamic nucleus
mediates satiety (destruction makes you always hungry)
lateral hypothalamic nucleus
mediates hunger (destruction makes you never hungry)
anterior hypothalamic nucleus
mediates heat dissipation (destruction makes you always hot)
posterior hypothalamic nucleus
mediates heat conservation (destruction makes you always cold)
arcuate hypothalamic nucleus
secretes dopamine (inhibits prolactin), secretes GHRH
medial preoptic hypothalamic nucleus
secretes GnRH, regulates sexual behavior
paraventricular hypothalamic nucleus
secretes oxytocin, TRH, CRH, some ADH
supraoptic hypothalamic nucleus
secretes ADH, some oxytocin
suprachiasmatic hypothalamic nucleus
circadian rhythm regulation, pineal gland function (melatonin)
ETEC
enterotoxigenic - traveler’s diarrhea (watery)
LT enterotoxin (cholera-like toxin, heat labile, increases cAMP)
ST enterotoxin (heat stable, increases cGMP)
colonizes and adheres to small intestine enterocytes via pili
increased chloride secretion and decreased sodium reabsorption by enterocytes
EHEC
enterohemorrhagic - bloody diarrhea from contaminated, undercooked meat
shiga-like toxin (inactivates 60s ribosomal subunit in host cells)
anaerobic glycolysis
occurs in oxygen-poor states
glucose -> pyruvate -> lactate in the cytosol
net 2 ATP / glucose
occurs in cancer cells and stem cells even in oxygen-rich states (causing tumor cells to take up more glucose, rapid cell division)
oxidative phosphorylation
occurs in oxygen-rich states
glucose -> pyruvate -> acetyl CoA -> TCA cycle -> NADH -> ETC
net 36 ATP / glucose
PDE5 inhibitors (sildenafil, tadalafil)
erectile dysfunction drugs
increase cGMP (mediates vascular smooth muscle relaxation) in penile corpora
side effect: can also inhibit PDE6 in retina causing vision to tint blue, sudden monocular vision loss with afferent pupillary defect (ischemic optic neuropathy)
phenotypic mixing
occurs when a host cell is co-infected with two viral strains
genome of virus A becomes coated with the surface proteins of virus B
progeny of virus A will have type A coat (not type B)
recombination
exchange of genes between 2 chromosomes by crossing over within regions of significant base sequence homology
reassortment
viruses with segmented genomes exchange an entire segment of genetic material
has potential to cause antigenic shift
complementation
1 of 2 viruses infecting a cell has a mutation that results in a nonfunctional protein, the nonmutated virus complements the mutated one by making a functional protein that serves both viruses
interference
one virus in a cell inhibits the release or replication of a second virus in the cell
transformation
incorporation of viral DNA into a host cell genome, altering genetic composition of host cell but not virus
adenosine action
vasodilation
nitric oxide action
vasodilation
atropine action
muscarinic antagonist
trisomy 13
patau syndrome
defect in fusion of prechordal mesoderm (midline defects)
severe intellectual disability, rocker-bottom feet, microphthalmia, microcephaly, holoprosencephaly, cleft lip/palate, polydactyly, cutis aplasia, polycystic kidney disease, omphalocele
trisomy 18
edwards syndrome
prominent occiput, rocker-bottom feet, intellectual disability, clenched fists with overlapping fingers, low-set ears, micrognathia, congenital heart disease, omphalocele, myelomeningocele
all prenatal screening markers are decreased
trisomy 21
down syndrome
intellectual disability, flat facies, prominent epicanthal folds, single palmar crease, incurved 5th finger, gap between first two tows, duodenal atresia, hirschprung disease, congenital heart disease, brushfield spots, early-onset alzheimer’s disease, increased risk of AML/ALL
increased hCG and inhibin in prenatal screening
affinity maturation
B cell process
process of enhancing the hypervariable region antigen binding affinity that occurs after initial binding of antigen to membrane-bound immunoglobulin on a naïve B lymphocyte and subsequent migration of that B-lymphocyte to a lymph node
results in new immunoglobulins with similar, better, or worse affinity for the antigen; only antibodies with better affinity will be selected for
occurs within the germinal center of the lymph node
isotype switching
B cell process
switches out the heavy chain of an antibody
negative selection
occurs in the thymic medullary epithelial and dendritic cells (after positive selection)
T cells with TCRs that bind with high affinity to self-antigen or self-MHC undergo apoptosis (eliminates overly-autoreactive cells, prevents autoimmunity)
positive selection
occurs in the thymic cortex
only double positive (CD4+/CD8+) T cells expressing TCRs that are able to self-bind MHC on cortical epithelial cells are allowed to survive (eliminates non-reactive cells)