Chapter 8: Taste

D

What changes occur in taste receptors when the membrane is depolarized during receptor potential?

A. Voltage-gated Ca2+ channels open, inhibiting the release of neurotransmitter.

B. Voltage-gated K+ channels open, triggering the release of neurotransmitter.

C. Voltage-gated K+ channels open, inhibiting the release of neurotransmitter.

D. Voltage-gated Ca2+ channels open, triggering the release of neurotransmitter.

B

How does the brain distinguish between alternative tastes?

A. By frequency distribution

B. By roughly labeled lines and population coding

C. Only by population coding

D. Only by precisely labeled lines

A

Why do we not confuse the tastes of bitter chemicals with sweet ones?

A. The receptor proteins are expressed in different cells.

B. There are 30 types of bitter receptors.

C. The tastes are differentiated by the olfactory cortex.

D. The chemicals activate different second messenger systems.

D

Which cranial nerve(s) carry taste information from the taste buds to the brain?

A. Abducens nerve, glossopharyngeal nerve, and hypoglossal nerve

B. Vagus nerve, olfactory nerve, and hypoglossal nerve

C. Trigeminal nerve, trochlear nerve, and facial nerve

D. Facial nerve, glossopharyngeal nerve, and vagus nerve

A

Which is true of population coding?

A. A large number of neurons specify the properties of a stimulus.

B. Temporal patterns of spiking codes determine the quality of an odor.

C. Receptor cells are each responsive to only a single taste.

D. There is an orderly spatial arrangement of neurons.

A

Which of the following occurs during sour taste transduction?

A. H+ influx depolarizes the cell.

B. Na+ influx depolarizes the cell.

C. Ca2+ influx depolarizes the cell.

D. K+ influx depolarizes the cell.

D

Salty taste is mediated by

A. None of the above

B. slow, metabotropic receptors.

C. hydrogen ions.

D. sodium ions.

B

People perceive sweet

A. only on the left side of the tongue.

B. anywhere on the tongue where there are taste receptors.

C. only on the right side of the tongue.

D. only at the tip of the tongue.

D

What of the following is not typically considered one of the basic tastes?

A. Umami

B. Salty

C. Sour

D. Spicy

D

What are chemoreceptors?

A. Chemically sensitive cells that mediate synapses at the neuromuscular junction

B. Cells releasing hormones into the extracellular environment

C. Special types of muscle cells sensitive to chemical changes in the extracellular milieu

D. Chemically sensitive cells that serve as sensory receptors

papillae

rough, bumpy elevations on dorsal surface of tongue

taste buds

sensory organs in the mouth that contain the receptors for taste

saltiness

detect low concentrations, salt-sensitive taste cells use a Na+ selective channel that is blocked by the drug amiloride. The amiloride-sensitive sodium channel is insensitive to voltage and generally always stays open. Na+ diffuses down its concentration gradient (flowing into the cell) and depolarizes because of the inward current. This receptor potential causes voltage-gated sodium and calcium channels to open near the synaptic vesicles, triggering the release of neurotransmitter molecules onto the gustatory afferent axon

sourness

because of their high acidity, H+ protons are the causative agents of acidity and sourness. H+ can bind to and block special K+-selective channels, which causes depolarization. H+ may also activate TRP channels, which the cation can cause depolarization as well.

bitterness

T1R2 and T2R3 that are G-protein coupled receptors, could be dimers (two proteins affixed to one another). Bitter substances are detected by the 25 different types of T2R and use a second messenger pathway to carry their signals to the afferent axons.

sweetness

dimers of G-protein coupled receptors and requires T1R2 and T1R3

umami

- T1R1 and T1R3 receptors, T1R1 determines whether the receptor is sensitive to amino acids or sweet tastants.

T1R1

determines whether the receptor is sensitive to amino acids or sweet tastants

population coding

representation of a particular object by the pattern of firing of a large number of neurons

apical end

chemically sensitive part of a taste receptor cell near the surface of the tongue

microvilli

at the end of the apical ends that project into the taste pore

taste pore

small opening on the surface of the tongue where the taste cell is exposed to the contents of the mouth

receptor potential

when a chemical activates a taste receptor cell, its membrane potential changes (usually depolarizing)

calcium

depolarization of the membrane causes voltage-gated ____ channels to open

depolarizes

What happens to membrane potential with chlorine efflux?

thalamus

taste goes through _____ first

olfactory axons, supporting cells, basal cells

cells of the olfactory epithelium

olfactory epithelium

a thin layer of tissue, within the nasal cavity, that contains the receptors for smell

basal cells

become new cells

supporting cells

produce mucus

transduction

in cilia, odor receptor proteins and odor receptor molecules that are ligand. If you open a calcium and sodium channel, it will flow into the cell and calcium will open chlorine channel

cAMP gated channels

involves population coding scheme, each receptor protein binds different odorants more or less readily, so its receptor cell is more or less sensitive to those odorants

tongue, gustatory nucleus, VPM, primary gustatory cortex

taste pathway from tongue to brain