chemical senses Flashcards
what is the role of hypothalamus and amygdala in human taste system
pleasure, aversion, food seeking, satiety, etc.
cranial nerve for epiglottis
10
taste in the fungiform papillae
sweet, umami
taste in the circumvallate papillae
bitter
foliate papillae taste
salt and sour
nerve for circumvallate papillae
9
cranial nerve for fungiform papillae
7
describe the makeup of papillae
contain a few 100 taste buds, each taste buds have 50-100 taste receptors,
are taste receptor cells neurons
no
what do taste receptor cells synapse on
gustatory afferent axons
which tastes have smaller taste thresholds
bitter and sour
what is the taste transduction cascade for umami
tastants activate T1R1 and T1R3, alpha subunit activates PLCB2 which transforms IP3 from PIP2, IP3 opens a Calcium channel on the endoplasmic reticulum which releases calcium into the cytoplasm, calcium influx opens TRPM5 channel causing Na influx, robust depolarization occurs, Calcium modulator channel is opened from the intracellular calcium, ATP is released, PX2/PX3 channels open as a result of ATP as neurotransmitter on the taste nerves
what is the taste transduction pathway for salty
amiloride sensitive sodium channels open due to salt tastants, depolarization occurs and flows downstream where it activates voltage-gated sodium, potassium, and calcium gated channels, calcium allows for transmitter release onto the taste afferents
what is the taste transduction pathway for sour
hydrogen sensitive TRP channels open in response to sour tastants, the depolarization travels downstream to open sodium, potassium, and calcium channels, the channels result in more depolarization and stimulate neurotransmitter release onto the taste afferents
what is the central taste pathway
taste buds, gustatory axons, medulla/brain stem, VPM thalamus, insular/frontal cortex, amygdala
where are the collateral inputs of the medulla
hypothalamus and amygdala
what happens if you ablate the P2X receptors
taste cells cannot depolarize and you cannot taste anything
describe olfactory transduction
receptor binds odorant, alpha subunit turns gtp to gdp, adynyl cyclase activated, camp synthesized, camp channels opened for na and ca causing influx, calcium binds to ca gated cl channel causing an influx of cl, cell is further depolarized (most of depolarization
describe olfactory repolarization
calcium begins to inhibit adynyl cyclase which decreases camp synthesization and decreases camp affinity of camp gated channels so some begin to close (by binding to CAM)
what kinds of inputs do each glomerulus receive
each glomerulus receives input from olfactory neurons expressing specific receptor proteins
describe the central olfactory pathways
olfactory receptor neurons synapse on the mitral and tufted cells in the glomureli (these make up the olfactory tract in the olfactory bulb). the olfactory tract extends to the pyriform cortex, olfactory tubercle, amygdala, and entorhinal cortex
-these project to the orbitofrontal cortex, thalamus, hypothalamus, and hippocampus
what is the role of DAG in bitter sweet umami pathway
