Physiology of Olfaction and Gustation Flashcards

1
Q

loss of the sense of smell

A

anosmia

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2
Q

loss of sense of taste

A

aguesia

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3
Q

taste buds are what type of cell?

A

specialized epithelia cells

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4
Q

the apical domain of taste buds contain what?

A

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

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5
Q

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

A

serotonin

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6
Q

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

A

serotonin

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7
Q

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

A

ATP

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8
Q

where does glutamate bind to?

A

an mGluR4 GPCR

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9
Q

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

A

ATP

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10
Q

what is released when bitter compounds bind to their GPCR?

A

ATP

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11
Q

olfactory cells are what type of neurons?

A

bipolar neurons

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12
Q

what do olfactory cells release as their NT?

A

glutamate

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13
Q

what is the olfactory receptor for odorants?

A

GPCR (Golf)

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14
Q

what is the second messenger in the olfactory receptor neuron?

A

cAMP

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15
Q

what does cAMP open in the olfactory receptor neuron?

A

cyclic-nucleotide gated channels

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16
Q

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

A

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

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17
Q

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

A

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

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18
Q

what is specific to bitter tastes?

A

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

19
Q

what happens to sensitivity as we age?

A

there is a decrease in sensitivity

20
Q

when does the sense of smell and taste begin?

A

in utero

21
Q

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

A

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

22
Q

what does sweet-tasted induced beta endorphin release activate?

A

endogenous opioid system

23
Q

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

A

by using sodium salts (most commonly is MSG)

24
Q

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

A

sugars

25
Q

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

A

post central gyrus, frontal operculum, and the insula

26
Q

CNs VII, IX, and X send their information where?

A

to the nucleus tractus solitarius

27
Q

what is the nucleus tractus solitarius?

A

it is an early site of gustatory-visceral integration

28
Q

where does the information go after the nucleus tractus solitarius?

A

to the VPM of the thalamus

29
Q

what is the purpose of the VPM?

A

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

30
Q

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

A

to the gustatory cortex

31
Q

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

A

to the orbitofrontal cortex

32
Q

what is the role of the orbitofrontal cortex?

A

it integrates visual, somatosensory, olfaction, and gustatory stimuli

33
Q

what is the role of the amygdala in gustation?

A

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

34
Q

what is the role of the medullary reflex arcs?

A

forms basis for salivating, mimetic responses and swallowing

35
Q

the projections of similar odorant receptors are collected into what?

A

one glomerulus

36
Q

glomerulus cells send a projection where?

A

mitral/tufted cell

37
Q

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

A

the olfactory system

38
Q

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

A

it controls appetite and hunger

39
Q

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

A

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

40
Q

what is the role of the anterior cortical amygdaloid nucleus?

A

emotional learning; olfactory fear conditioning

41
Q

what is the role of the periamygdaloid cortex?

A

integration of emotional aspect elicited by odor

42
Q

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

A

important in memory formation; memory upon odor sensation

43
Q

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

A

the olfactory bulb and the dentate gyrus of the hippocampus

44
Q

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

A

parkinson disease