Gustatory System

Question 1

What are the 5 basic tastes?

Answer 1

Sweet, salty, bitter, umami, sour

Question 2

How are tastants for the 5 basic tastes translated into membrane potential signals?

Answer 2

Tastant disolved in saliva and interacts with taste receptor cells on taste buds
Activates a taste cell → depolarization → activates pathway

Question 3

What receptors do each of the 5 tastes use?

Which use GPCRs and which use ion channels?

Also name the specific receptors

Answer 3

Sweet, umami, bitter: GPCRs
* Umami: T1R1 & T1R3
* Sweet: T1R2 & T1R3
* Bitter: T2Rs
Salty, sour: specific ion channels

Question 4

Why isn’t it a problem that we can’t discriminate well between bitter tastants?

Answer 4

Bitter is meant to cause avoidance

Question 5

What cranial nerves are involved in the gustatory pathway?

Answer 5

CN VII, IX, X

Question 6

Why can’t pandas taste umami and why can’t cats tast sweet?

What receptors are involved?

Answer 6

Panda: T1R1 is a pseudogene
Cat: T1R2 is a pseudogene

Question 7

Experiment to show that the pathway determines behavior but not the tastant or taste receptor

Question 8

What is the taste pathway?

Answer 8

Tongue → CN VII, IX, X → Brain stem → thalamus → gustatory cortex

Question 9

What is the mechanism on the tongue?