physiology of olfaction and gustation Flashcards
what tastes triggers ATP release
sweet, bitter, umami
what tastes trigger serotonin release
sour and salty
what cells are stimulated by the ATP released from sweet/bitter/umami receptor cells
- post synaptic primary gustatory neurons
- pre-synaptic salty/sour receptor cells to stimulate serotonin release
- autocrine release
what cells are stimulated by the serotonin released from salty/sour receptor cells
-post synaptic primary gustatory neurons
via what channels does sodium enter the salty receptor cells
epithelial Na channel (ENaC)
what ion stimulates sour receptor cells
protons inhibit K channels => depolarization
what channel is activated by salty/bitter/umami binding to it’s GPCR
TRPM5
via what channel is ATP released from a sweet/bitter/umami receptor
Panx1
what is the Umami receptor and what is it’’s ligand
mGluR4
glutamate
what taste receptor binds with super high affinity and why
bitter b/c toxic substances are bitter
what is the path of flavor information from the taste receptor
nucleus tractus solitarius => VPM => orbitofrontal cortex, amygdala and hypothalamus
what three structures make up the gustatory cortex
- insula
- frontal operculum
- postcentral gyrus
what nerve innervates the taste buds of the anterior 2/3 of the tongue
CN VII (chorda tympani)
what nerve innervates the taste buds of the posterior 1/3 of the tongue
CN IX (lingual-tonsillar branch)
what nerve innervates the taste buds of the epiglottis and esophagus
CN X (superior laryngeal n)
at what structure does information from the taste buds, ANS and visceral afferents integration occur
nucleus tractus solitarius
where does discrimination of taste occur
VPM of the thalamus
where does memory formation of a flavor occur
insular cortex
where does emotional response to taste occur
amygdala
what type of neurons are olfactory cells
bipolar
what kind of receptor are olfactory receptors (ORs)
GPCRs (Golf)
what is the downstream affect of Golf receptor binding
increase cAMP => cyclic nucleotide gated channels (CNGC) open => depolarization
via what two mechanisms does adaptation to a smell occur
1) decreased sensitivity of CNGC to cAMP
2) receptor phosphorylated and inactivated
what cells of the olfactory bulb increase specificity of a signal
periglomerular cells
granule cells
what NT is released by olfactory neurons
glutamate
what is the function of the input from the piriform cortex to the lateral hypothalamus
control of appetite and hunger
via what pathway does integration of taste, sight and smell occur
piriform cortex => thalamus => medial orbitofrontal cortex
where does emotional learning and olfactory fear conditioning occur
anterior cortical amygdaloid nucleus
what occurs at the periamygdaloid cortex
integration of emotion ilicited by odor
what structure relays olfactory information to the hippocampus
entorhinal cortex
what three inputs are integrated for perception of flavor
- gustatory input from gustatory cortex
- olfactory input (mostly from piriform cortex)
- somatosensory information from the mouth
what occurs when you have a cold and cant taste your food
thickened mucus blocks odorants from binding
