Taste and Smell Sensation Flashcards Preview

MABS Neuroscience > Taste and Smell Sensation > Flashcards

Flashcards in Taste and Smell Sensation Deck (30)
Loading flashcards...
1
Q

what are the five basic taste sensation?

A
sweet
salt
sour
bitter
umami
2
Q

sugars, saccharin, alcohol, and some amino acids

A

sweet

3
Q

metal ions

A

salt

4
Q

hydrogen ions

A

sour

5
Q

alkaloids such as quinine and nicotine

A

bitter

6
Q

elicited by the amino acid glutamate

A

umami

7
Q

what is sweet taste sensation?

A

sugars, saccharin, alcohol, and some amino acids

8
Q

what is salt taste sensation?

A

metal ions

9
Q

what is sour taste sensation?

A

hydrogen ions

10
Q

what is bitter taste sensation?

A

alkaloids such as quinine and nicotine

11
Q

what is umami taste sensation?

A

elicited by the amino acid glutamate

12
Q

where are the taste buds found?

A

papillae of the tongue mucosa

13
Q

what are the three types of papillae?

A

filiform, fungiform, and circumvallate

14
Q

what are taste receptor cells derived from? what is the life span of each taste receptor cell?

A

skin (epithelial) cells

typically a week

15
Q

in order to be tasted, what must happen to the chemical?

A

Must be dissolved in saliva

Must contact gustatory hairs

16
Q

what is the effect in the binding of the food chemical?

A

Depolarizes the taste cell membrane, releasing neurotransmitter

Initiates a generator potential that elicits an action potential

17
Q

what is salty taste mediated by?

A

by an epithelial Na+ channel (ENaC) that is sensitive to amiloride.

18
Q

what is sour taste mediated by?

A

by H+ entering through the same ENaC channel or by the effect of low pH inhibiting a K+ channel.

19
Q

what is the effect of the depolarization for salt and sour taste buds?

A

The resulting depolarization opens voltage-gated Ca2+ channels, increasing [Ca2+]i and leading to transmitter release.

20
Q

what is sweet taste mediated by?

A

Sugar binds to a 7-transmembrane receptor that activates heterotrimeric G protein, stimulating AC, increasing cAMP, and activating PKA, which then closes a K+ channel

21
Q

what is the effect of the depolarization for sweet taste transduction?

A

The resulting depolarization opens voltage-gated Ca2+ channels, increasing [Ca2+]i and leading to transmitter release

22
Q

what is bitter taste mediated by? since there is many, list them and effect of the deplorization for that pathway

why is bitter taste unique?

A

A bitter compound directly inhibits K+ channels. The resulting depolarization opens voltage-gated Ca2+ channels, increasing [Ca2+]i and leading to transmitter release.

A ligand binds to a 7-transmembrane receptor and activates a G protein called gustducin that stimulates phosphodiesterase. The resultant decrease in [cAMP]i somehow leads to depolarization.

Ligand binds to a receptor that is linked to a G protein, which activates phospholipase C. The resultant increase in [IP3] releases Ca2+ from stores, raises [Ca2+]i, and leads to transmitter release

Helps us to detect for poisons or toxins we ingest, this is why this has so many different channels for bitter sensation and so the material can expelled from the mouth from being digested

23
Q

what is umami taste mediated by and resulting depolarization?

A

Glutamate binds to a glutamate-gated, nonselective cation channel and opens it. The resultant depolarization opens voltage-gated Ca2+ channels, increases [Ca2+]i, and leads to transmitter release.

24
Q

where does the signal go after taste transduction takes place?

A

the gustatory pathway from CN 7,9,10 of broadmen area 43, note that this pathway is ipsilateral

25
Q

describe the gustatory pathway?

A

taste bud to solitary nucleus tract of the medulla (NTS) to the VPM of the thalamus then to the gustatory cortex for taste then the hypothalamus and limbic system for the appreciation of taste

26
Q

where is the organ of smell located?

A

The organ of smell is the olfactory epithelium, which covers the superior nasal concha

27
Q

how does smell get to the olfactory bulb?

A

it through the cilia located in the superior nasal conchae through the olfactory epithelium across the cribriform plate then to the olfactory bulb via CN I

28
Q

T/F, once you go deeper into the brain innervations travel to opposite sides of the brain?

A

T

29
Q

how does smell trigger an action potential?

A

Olfactory receptors respond to several different odor-causing chemicals

When bound to ligand these proteins initiate a G protein mechanism, which uses cAMP as a second messenger

cAMP opens Na+ and Ca2+ channels, causing depolarization of the receptor membrane that then triggers an action potential

30
Q

once in the olfactory bulb how are synapses formed?

A

synapse with mitral and tufted at glomeruli

Axonic processes of mitral and tufted cells constitute cranial nerve I (CNI)

Decks in MABS Neuroscience Class (49):