Taste and Smell Sensation

Question 1

what are the five basic taste sensation?

Answer 1

sweet
salt
sour
bitter
umami

Question 2

sugars, saccharin, alcohol, and some amino acids

Answer 2

sweet

Question 3

metal ions

Answer 3

salt

Question 4

hydrogen ions

Answer 4

sour

Question 5

alkaloids such as quinine and nicotine

Answer 5

bitter

Question 6

elicited by the amino acid glutamate

Answer 6

umami

Question 7

what is sweet taste sensation?

Answer 7

sugars, saccharin, alcohol, and some amino acids

Question 8

what is salt taste sensation?

Answer 8

metal ions

Question 9

what is sour taste sensation?

Answer 9

hydrogen ions

Question 10

what is bitter taste sensation?

Answer 10

alkaloids such as quinine and nicotine

Question 11

what is umami taste sensation?

Answer 11

elicited by the amino acid glutamate

Question 12

where are the taste buds found?

Answer 12

papillae of the tongue mucosa

Question 13

what are the three types of papillae?

Answer 13

filiform, fungiform, and circumvallate

Question 14

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

Answer 14

skin (epithelial) cells

typically a week

Question 15

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

Answer 15

Must be dissolved in saliva

Must contact gustatory hairs

Question 16

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

Answer 16

Depolarizes the taste cell membrane, releasing neurotransmitter

Initiates a generator potential that elicits an action potential

Question 17

what is salty taste mediated by?

Answer 17

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

Question 18

what is sour taste mediated by?

Answer 18

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

Question 19

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

Answer 19

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

Question 20

what is sweet taste mediated by?

Answer 20

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

Question 21

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

Answer 21

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

Question 22

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?

Answer 22

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

Question 23

what is umami taste mediated by and resulting depolarization?

Answer 23

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.

Question 24

where does the signal go after taste transduction takes place?

Answer 24

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

Question 25

describe the gustatory pathway?

Answer 25

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

Question 26

where is the organ of smell located?

Answer 26

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

Question 27

how does smell get to the olfactory bulb?

Answer 27

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

Question 28

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

Answer 28

T

Question 29

how does smell trigger an action potential?

Answer 29

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

Question 30

once in the olfactory bulb how are synapses formed?

Answer 30

synapse with mitral and tufted at glomeruli

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