07b: Taste and Smell

Question 1

Both taste and smell receptors are stimulated by:

Answer 1

molecules (in solution)

Question 2

Taste receptors are grouped together as (X), which are found in (Y).

Answer 2

X = taste buds
Y = papillae

Question 3

List the cell types found in one taste bud.

Answer 3

Types I and II: supporting cells (with microvilli)
Type III: sensory receptor
Type IV: basal cell

Question 4

Basal cells found in taste buds come from (X) and are important for (Y).

Answer 4

X = migration of surrounding epithelium
Y = production (via differentiation) into new sensory receptor cells

Question 5

T/F: there is continual turnover of sensory receptors in taste cells.

Answer 5

True

Question 6

List taste regions on tongue, from distal to proximal.

Answer 6

1. Sweet
2. Salty
3. Sour
4. Bitter

Question 7

Taste molecules interact with (ion channels/GPCR). All stimuli elicit (increase/decrease) in (X).

Answer 7

Either;
Increase
X = intracellular Ca

Question 8

Gustducin is a(n) (X) involved in which specific sensations?

Answer 8

X = GPCR

Sweet and bitter(2) tastes

Question 9

T/F: Gustducin AA sequence and biochemical properties are similar to rod transducin.

Answer 9

True

Question 10

Salty taste is result of (X) ion, which (depolarizes/hyperpolarizes) taste cells by:

Answer 10

X = Na
Depolarizes;
Passive influx through amiloride-sensitive Na channels

Question 11

Na entering taste cell does so through (passive/active) transport through (X), located on (apical/basal) surface of cell.

Answer 11

Passive;
X = amiloride-sensitive Na channel
Apical

Question 12

How is proper Na and (X) ion concentration maintained in taste cell?

Answer 12

X = K

Na/K pump in basolateral membrane

Question 13

Sour taste is produced by (X). Degree of “sourness” depends on (Y).

Answer 13

X = acids;
Y = proton concentration

Question 14

T/F: Sour(1) and Sour(2) involve similar mechanisms in depolarization of taste cell.

Answer 14

False

Question 15

Sour(1) mechanism of (depolarization/hyperpolarization).

Answer 15

Depolarization;

Blocks K efflux from cell

Question 16

Sour(2) mechanism of (depolarization/hyperpolarization).

Answer 16

Depolarization;

Influx through amiloride-sensitive Na channels

Question 17

List the ion(s) that pass through amiloride-sensitive (X) channels in taste sensation.

Answer 17

X = Na

Na and H

Question 18

Bitter sensation is mostly elicited by (X). Give an example.

Answer 18

X = poisonous/toxi plant substances;

Quinine or CaCl2

Question 19

T/F: Bitter(1) and Bitter(2) involve two different GPCR.

Answer 19

False - Bitter(1) doesn’t involve GPCR

Question 20

T/F: Bitter(1) and Sour(1) involve similar mechanisms in depolarization of taste cell.

Answer 20

True

Question 21

(X) taste(s) involve gustducin, which (activates/suppresses) (Y). The key second messenger is (Z), which mediates:

Answer 21

X = bitter(2) and sweet;
Activates;
Y = PLC
Z = IP3

Ca release from intracellular stores

Question 22

T/F: All sweet taste transduction mechanisms use GPCR.

Answer 22

True

Question 23

Sweet taste mechanism involves activation of (X), which immediately stimulates:

Answer 23

X = Gustducin

Either AC or PLCd

Question 24

(X) molecule elicits the unique umami sensation, which involves (Y) receptor.

Answer 24

X = L-gluatamate
Y = metabotropic glutamate receptor

Question 25

Main ingredient that makes food hot/spicy is (X), the receptor for which is (ion channel/GPCR) for both (X) and (Y).

Answer 25

X = caspaicin; Ion channel Y = painful heat stimulation

Question 26

When activated by caspaicin or by (X), the receptor causes:

Answer 26

X = heat; influx of Ca and Na ions

Question 27

Taste sensory cells have axons that synapse on:

Answer 27

They don't have axons!

Question 28

Mature olfactory receptor has long, thin (X) that terminates in (Y) which gives rise to about 5 (Z).

Answer 28

``` X = dendrite; Y = knob Z = cilia ```

Question 29

(X) processes on ends of olfactory receptors lie in thin layer of (Y), secreted by (Z) cells.

Answer 29

``` X = cilia; Y = mucus Z = supporting ```

Question 30

Olfactory receptors arise from maturation of (X) cells.

Answer 30

X = basal

Question 31

Olfactory molecules diffuse through (X) and reach/bind specific receptors in plasma membrane of (Y).

Answer 31

``` X = mucus; Y = cilia ```

Question 32

Binding of olfactory molecule to receptor on (X) initiates (rapid/gradual) (activation/suppression) of (Y) and formation of (Z).

Answer 32

X = cilia; Rapid activation; Y = G-proteins Golf, then AC Z = cAMP

Question 33

In olfactory sensation, production of (X) is key to (opening/blocking) (Y) channels, resulting in:

Answer 33

X = cAMP; Opening; Y = cyclic NT-gated (CNG) Influx of Na and Ca (depolarization)

Question 34

In olfactory sensation, the influx of (X) ions causes both (depolarization/hyperpolarization) and (opening/closing) of (Y) channels. What effect does this have?

Answer 34

X = Na and Ca; Depolarization; Opening; Y = Ca-gated Cl channels Efflux of Cl out of cell and further depolarization

Question 35

Olfactory sensation: when (de/hyper)-polarization of (X) spreads to (Y), action potentials are conducted to the first relay station, (Z).

Answer 35

Depolarization; X = cilia; Y = cell body; Z = olfactory bulb (mitral cells)

Question 36

(High/low) intracellular concentration of (X) has been shown to play role in odor sensitivity regulation by directly (activating/suppressing) (Y).

Answer 36

High; X = Ca Activating; Y = Calmodulin

Question 37

Odor desensitization is a result of desensitization of (X) channels by (Y).

Answer 37

``` X = cAMP-gated (CNG) Y = Ca-calmodulin complex ```

Question 38

A given olfactory receptor shows (narrow/broad) spectrum of sensitivity to different odors - about (X) number.

Answer 38

Broad; | X = 10-12

Question 39

Primary afferent neurons in olfactory system are (X). Where are second order neurons?

Answer 39

X = olfactory receptor cells; Mitral cells (in olfactory bulb) are second-order neurons

Question 40

About (X) number of olfactory afferent fibers synapse on one mitral cell.

Answer 40

X = 1000

Question 41

Olfactory receptors respond to prolonged stimulation with (slow/fast) adaptation.

Answer 41

Slow

Question 42

Adaptation to orders is likely due to (central/peripheral) neural property in olfactory pathway.

Answer 42

Central (inhibitory interactions)

Question 43

T/F: Olfactory bulb is recipient of many afferent inputs from the brain.

Answer 43

True

Question 44

Individual olfactory receptors respond to (one/many) types of odorants, and have (same/different) responses to the same odorant.

Answer 44

Many; different

Question 45

Regardless of specific taste type, they all cause (depolarization/hyperpolarization) that causes (X), which causes (Y), which causes (Z).

Answer 45

Depolarization; X = Action Potential; Y = Ca influx Z = NT release

Question 46

T/F: All taste receptors that activate GPCR are involved in releasing Ca from intracellular stores.

Answer 46

False

Question 47

T/F: Salt taste receptor is open at rest.

Answer 47

True

Question 48

One form of sweet activates AC. What's the pathway after that?

Answer 48

1. Produces cAMP 2. Activates PKA 3. Phosphorylation/blocking K channels on basolateral membrane 4. Depolarization

Question 49

Which tastes cause eventual release of Ca from intracellular stores?

Answer 49

Sweet and bitter(2)