physiology of olfaction and gustation

Question 1

what tastes triggers ATP release

Answer 1

sweet, bitter, umami

Question 2

what tastes trigger serotonin release

Answer 2

sour and salty

Question 3

what cells are stimulated by the ATP released from sweet/bitter/umami receptor cells

Answer 3

• post synaptic primary gustatory neurons
• pre-synaptic salty/sour receptor cells to stimulate serotonin release
• autocrine release

Question 4

what cells are stimulated by the serotonin released from salty/sour receptor cells

Answer 4

-post synaptic primary gustatory neurons

Question 5

via what channels does sodium enter the salty receptor cells

Answer 5

epithelial Na channel (ENaC)

Question 6

what ion stimulates sour receptor cells

Answer 6

protons inhibit K channels => depolarization

Question 7

what channel is activated by salty/bitter/umami binding to it’s GPCR

Answer 7

TRPM5

Question 8

via what channel is ATP released from a sweet/bitter/umami receptor

Answer 8

Panx1

Question 9

what is the Umami receptor and what is it’’s ligand

Answer 9

mGluR4

glutamate

Question 10

what taste receptor binds with super high affinity and why

Answer 10

bitter b/c toxic substances are bitter

Question 11

what is the path of flavor information from the taste receptor

Answer 11

nucleus tractus solitarius => VPM => orbitofrontal cortex, amygdala and hypothalamus

Question 12

what three structures make up the gustatory cortex

Answer 12

• insula
• frontal operculum
• postcentral gyrus

Question 13

what nerve innervates the taste buds of the anterior 2/3 of the tongue

Answer 13

CN VII (chorda tympani)

Question 14

what nerve innervates the taste buds of the posterior 1/3 of the tongue

Answer 14

CN IX (lingual-tonsillar branch)

Question 15

what nerve innervates the taste buds of the epiglottis and esophagus

Answer 15

CN X (superior laryngeal n)

Question 16

at what structure does information from the taste buds, ANS and visceral afferents integration occur

Answer 16

nucleus tractus solitarius

Question 17

where does discrimination of taste occur

Answer 17

VPM of the thalamus

Question 18

where does memory formation of a flavor occur

Answer 18

insular cortex

Question 19

where does emotional response to taste occur

Answer 19

amygdala

Question 20

what type of neurons are olfactory cells

Answer 20

bipolar

Question 21

what kind of receptor are olfactory receptors (ORs)

Answer 21

GPCRs (Golf)

Question 22

what is the downstream affect of Golf receptor binding

Answer 22

increase cAMP => cyclic nucleotide gated channels (CNGC) open => depolarization

Question 23

via what two mechanisms does adaptation to a smell occur

Answer 23

1) decreased sensitivity of CNGC to cAMP

2) receptor phosphorylated and inactivated

Question 24

what cells of the olfactory bulb increase specificity of a signal

Answer 24

periglomerular cells

granule cells

Question 25

what NT is released by olfactory neurons

Answer 25

glutamate

Question 26

what is the function of the input from the piriform cortex to the lateral hypothalamus

Answer 26

control of appetite and hunger

Question 27

via what pathway does integration of taste, sight and smell occur

Answer 27

piriform cortex => thalamus => medial orbitofrontal cortex

Question 28

where does emotional learning and olfactory fear conditioning occur

Answer 28

anterior cortical amygdaloid nucleus

Question 29

what occurs at the periamygdaloid cortex

Answer 29

integration of emotion ilicited by odor

Question 30

what structure relays olfactory information to the hippocampus

Answer 30

entorhinal cortex

Question 31

what three inputs are integrated for perception of flavor

Answer 31

- gustatory input from gustatory cortex - olfactory input (mostly from piriform cortex) - somatosensory information from the mouth

Question 32

what occurs when you have a cold and cant taste your food

Answer 32

thickened mucus blocks odorants from binding