Physiology of Olfaction and Gustation

Question 1

loss of the sense of smell

Answer 1

anosmia

Question 2

loss of sense of taste

Answer 2

aguesia

Question 3

taste buds are what type of cell?

Answer 3

specialized epithelia cells

Question 4

the apical domain of taste buds contain what?

Answer 4

microvilli, tastant receptors, voltage-gated ion channels, and TRP receptors

Question 5

what is the NT released when sours (H+ ions) tastants bind?

Answer 5

serotonin

Question 6

what is the NT released when salty (Na+ ions) bind?

Answer 6

serotonin

Question 7

what is the NT released when sugars bind to the GPCR?

Answer 7

ATP

Question 8

where does glutamate bind to?

Answer 8

an mGluR4 GPCR

Question 9

what is released when glutamate (umami) binds to it’s receptor?

Answer 9

ATP

Question 10

what is released when bitter compounds bind to their GPCR?

Answer 10

ATP

Question 11

olfactory cells are what type of neurons?

Answer 11

bipolar neurons

Question 12

what do olfactory cells release as their NT?

Answer 12

glutamate

Question 13

what is the olfactory receptor for odorants?

Answer 13

GPCR (Golf)

Question 14

what is the second messenger in the olfactory receptor neuron?

Answer 14

cAMP

Question 15

what does cAMP open in the olfactory receptor neuron?

Answer 15

cyclic-nucleotide gated channels

Question 16

what is the role of the cyclic-nucleotide gated channels?

Answer 16

they allow Na+ and Ca2+ to influx into the cell and depolarization occurs

Question 17

what are the three mechanisms for olfactory receptor neuron adaptation to a smell?

Answer 17

enzymatic breakdown of cAMP, reduced affinity for cAMP, Golf can become phosphorylated

Question 18

what is specific to bitter tastes?

Answer 18

the bitter-tuned GPCRs bind their ligand with very high affinity compared to the other taste receptors

Question 19

what happens to sensitivity as we age?

Answer 19

there is a decrease in sensitivity

Question 20

when does the sense of smell and taste begin?

Answer 20

in utero

Question 21

why is there an analgesic effect of sweet-solutions for infants?

Answer 21

anti-nociceptive action- sweet-tasted induced beta-endorphin release

Question 22

what does sweet-tasted induced beta endorphin release activate?

Answer 22

endogenous opioid system

Question 23

how can you suppress a bitter taste at the level of the bitter-receptor?

Answer 23

by using sodium salts (most commonly is MSG)

Question 24

how can you suppress the sense of bitterness at the cognitive level?

Answer 24

sugars

Question 25

the gustatory cortex is made up of three cortical areas. What are they?

Answer 25

post central gyrus, frontal operculum, and the insula

Question 26

facial nerve (VII), glossopharyngeal nerve (IX), vagus nerve (X) send their information where?

Answer 26

to the nucleus tractus solitarius

Question 27

what is the nucleus tractus solitarius?

Answer 27

it is an early site of gustatory-visceral integration

Question 28

where does the information go after the nucleus tractus solitarius?

Answer 28

to the VPM of the thalamus

Question 29

what is the purpose of the VPM?

Answer 29

it is the relay station for taste perception. Begins discriminative aspects of tast

Question 30

where does the VPM send it's information from the NTS?

Answer 30

to the gustatory cortex

Question 31

where does the gustatory cortex send its information from the VPM?

Answer 31

to the orbitofrontal cortex

Question 32

what is the role of the orbitofrontal cortex?

Answer 32

it integrates visual, somatosensory, olfaction, and gustatory stimuli

Question 33

what is the role of the amygdala in gustation?

Answer 33

affective aspects of eating, emotional context to eating, and memory of eating

Question 34

what is the role of the medullary reflex arcs?

Answer 34

forms basis for salivating, mimetic responses and swallowing

Question 35

the projections of similar odorant receptors are collected into what?

Answer 35

one glomerulus

Question 36

glomerulus cells send a projection where?

Answer 36

mitral/tufted cell

Question 37

what is the only sensory system that does not route through the thalamus before connecting to the cortex?

Answer 37

the olfactory system

Question 38

what is the role of the piriform cortex--> the lateral hypothalamus?

Answer 38

it controls appetite and hunger

Question 39

what is the role of the piriform cortex--> thalamus--> medial orbitofrontal cortex?

Answer 39

integration of taste, sight, and smell; appreciation of the flavor of food

Question 40

what is the role of the anterior cortical amygdaloid nucleus?

Answer 40

emotional learning; olfactory fear conditioning

Question 41

what is the role of the periamygdaloid cortex?

Answer 41

integration of emotional aspect elicited by odor

Question 42

what is the role of the entorhinal cortex--> hippocampus?

Answer 42

important in memory formation; memory upon odor sensation

Question 43

adult neurogenesis is thought to occur in two places in the brain. Where?

Answer 43

the olfactory bulb and the dentate gyrus of the hippocampus

Question 44

in what disease are neurons of the olfactory system among the first to demonstrate pathology?

Answer 44

parkinson disease