7.3: Sensing Temperature and Taste

Question 1

temperature fibers are typically:

Answer 1

C and AS fibers, like nociceptors

Question 2

which channels are temp sensitive?

Answer 2

transient receptor potential channels (TRPCs)

Question 3

capsaicin receptor/ hot temp receptor

Answer 3

TRPV1

Question 4

medium heat receptors

Answer 4

TRPV3/ TRPV4

Question 5

channel that opens in response to cold temp

Answer 5

TRPM8

Question 6

channel that opens in response to NOXIOUS cold

Answer 6

TRPA1

Question 7

Why can a person adapt to spicy diets?

Answer 7

because their TRPV1 capsaicin/hot temp channels gets deactivated after prolonged stimulation

Question 8

menthol causes ____ to open at higher temps. Makes things taste cool even at regular temps

Answer 8

TRPM8

Question 9

each tastebud houses ___ ___

Answer 9

taste cells

Question 10

each tastecell on a tastebud houses taste ___

Answer 10

receptors (GPCRs)

Question 11

activation of GPCR taste receptors release ___ onto ___ ___ that project to ___ ___ ____

Answer 11

activation of GPCR taste receptors release ATP onto SENSORY AXONS that project to NUCLEUS TRACTUS SOLITARIUS

Question 12

T1 receptors have affinity for

Answer 12

sweet or umami.

Question 13

T2 receptors have affinity for

Answer 13

bitter

Question 14

activation of a taste receptor recruits the ____ gProtein.

Answer 14

gustducin

Question 15

how does the gustucin in the taste cell receptor activate sensory neurons

Answer 15

has 2 subunits: alpha unit activates phosphodiesterase
beta subunit activates PLC

Ca2+ influx due to Gustducin activation opens TRPM5 channel (cation channel)

Question 16

which T1 receptor couples are sensitive to sweetness? to umami?

Answer 16

T1R2+T1R3 = sugar affinity

T1R1 + T1R3 = umami affinity (sensitive to MSG)

Question 17

the ____ channel receptor responds to acidity

Answer 17

PKD2L1

Question 18

Why can PKD2L1 channel open in response to CO2?

Answer 18

because there is carbonic anhydrase surrounding it and it converts CO2 to H+ and HCO3-

Question 19

Which channel detects salt? Where are these channels present?

Answer 19

epithelial Na+ channel. Present in the taste cells and kidney. when Na+ in ECF, epithelial channels open and Na+ flows into the cell, depolarizing it

Question 20

____ involved in sensing presence of fatty acids

Answer 20

CD36

Question 21

___ is the principle gustatory neurotransmitter

Answer 21

ATP

Question 22

what happens when ATP is released by the taste receptors?

Answer 22

when gustatory sensory neurons bind ATP, P2X receptor channel opens and + flows into axon terminal.

Question 23

taste receptors release atp onto sensory neurons, which project to ___ ___ __ in the ____. this region can project into 3 other regions. what are they?

Answer 23

nucleus tractus solidarius in the medulla. NTS can project into amygdala, primary gustatory cortex for cognitive interpretation of taste, and portions of the thalamus for appetite regulation

Question 24

3 cranial nerves that gustatory senses are conveyed to the brain through

Answer 24

1) Facial nerve: conveys info from tip of tongue
2) Glossopharyngeal nerve: innervates rest of the tongue
3) Vagus nerve; innervates buds on the roof of mouth

Question 25

CB1 receptor activation is salient for ___ response enhancement

Answer 25

sweet

Question 26

PKD2L1 responds to taste acidity. Which channels respond to TISSUE acidity?

Answer 26

ASIC channel: responsive to increased Co2 and opens channels to + ion flow during low pH. Regulates increased breathing

TRPV1 channel: Also opens in response to capsaicin or heat. Opens in response to tissue acidity and conveys pain.

Question 27

___ ___ organs on the carotid body senses blood osmolarity as well as hormones, glucose levels and blood borne toxins.

Answer 27

Circum ventricular organs.

Question 28

the circumventricular organs on the carotid body passes info onto the ___ ___ ___ to help adjust breathing and other processes

Answer 28

carotid sinus nerve

Question 29

two types of cells that the carotid body has that helps sense blood chemistry. what is the main neurotransmitter used? How are the cells made?

Answer 29

1) glomus/type 1 cells: depolarize when blood Co2 levels are low and release ATP to transmit info to the carotid sinus nerve
2) type 2 cells: give rise to glomus cells during periods of CHRONIC HYPOXIA