Lec 15

Question 1

Gustation and olfacton

Answer 1

Taste and smell

Question 2

2 roles of gustation

Answer 2

Evaluating the nutritional content of food

Preventing the ingestion of toxic compounds

Question 3

Umami-Savoriness

Answer 3

Foods rich in glutamates including MSGs

Question 4

4 types of receptors

Answer 4

types 1-3 are taste receptors

type 4 is basal cells that become new taste receptors

Question 5

Type 1 cell

Answer 5

Salty taste

Question 6

Type 3 cell

Answer 6

Sour taste

Question 7

Type 2 cell

Answer 7

Different variants for sweet, umami and bitter

Question 8

Type 1 cell , ionotropic mechanism

Answer 8

when Na+ in mouth increases it passes through permeable Na+ channels (not voltage gated)

Very insensitive (saliva has 10nM of NaCl but food needs 50nM to taste salty

Question 9

Type 3 cell, ionotropic mechanism

Answer 9

Detects H+ (acid ions)
Involves a transient receptor potential channel (TRPP3) conjoined with a Polycystic kidney disease family protein (PKD1L3)

Question 10

TRPP3

Answer 10

Permits passage of protons

Weak acids also pass through the lipid membrane

H+ ions close K+ channels and the cell depolarizes

This activates voltage gated sodium channels

This leads to Voltage gates Ca2+ channels opening
Serotonin is then released

Question 11

Type 2 cells, metabotropic mechanism (sweet)

Answer 11

Heterodimer of two taste receptor proteins (T1R2 and T1R3)

Question 12

Type 2 cells, metabotropic mechanism (umami)

Answer 12

Heterodimers of two taste receptor proteins (T1R1 and T1R3)

Question 13

Type 2 cells, metabotropic mechanism (Bitter)

Answer 13

Dimers of two taste receptor proteins from the T2R family

Question 14

Type 2 cells, metabotropic mechanism

Answer 14

TRPM5 channel opens leading to an influx which depolarizes the cell

Action potential is generated

Question 15

Type 2 cells releasing ATP

Answer 15

2nd messenger Ca2+ also open Panx1 channels which releases ATP in the extracellular space