Chapter 33. Sensory Systems

Question 1

vertebrate photoreceptor cell that functions in bright light and are responsible for color vision.

Answer 1

Cone

Question 2

One of the five primary tastes that sometimes classifies compounds that are sometimes potentially harmful or toxic, present in alkaloids or other plant products.

Answer 2

bitter

Question 3

a specific region of the nose containing approximately 1 million sensory neurons that detects odorants.

Answer 3

Main olfactory epithelium

Question 4

sodium channels that are important in the detection of the taste of salt. These channels are inhibited by amiloride, which also mutes the taste of salt.

Answer 4

Amiloride-sensitive Na+ channel

Question 5

An a subunit, uniquely expressed in olfactory cilia, of a G protein associated with odorant receptors.

Answer 5

G(olf)

Question 6

a light-absorbing group, such as 11-cis-retinal in rhodopsin.

Answer 6

Chromophore

Question 7

A channel in rod cells that opens in response to cGMP to allow entry of calcium and sodium ions into the cell; closing of the channel in response to cGMP hydrolysis initiates the visual signal-transduction pathway.

Answer 7

cGMP-gated ion channel

Question 8

a protein that plays a role in the termination of the visual signal transduction pathway by binding to phosphorylated rhodopsin and preventing further interaction with transducin. Arrestin may function similarly in other 7TM dependent signal transduction pathways.

Answer 8

arrestin

Question 9

ion channels expressed in nociceptors that open in response noxious stimuli such as heat, acidity or chemicals such as capsaicin, the chemical responsible for the “hot” taste of spicy food. Also called the vanilloid receptor 1, VR1.

Answer 9

capsaicin receptor (VR1)

Question 10

an enzyme that hydrolyzes cGMP to GMP. In the visual system, this hydrolysis leads to the generation of an action potential.

Answer 10

cGMP phospodiesterase

Question 11

an enzyme that phosphorylates activated rhodopsin at multiple serine and threonine residues to provide a binding site for the inhibitory protein arrestin.

Answer 11

rhodopsin kinase

Question 12

a 7TM receptor of rod cells that, when bound to 11-cis-retinal to form rhodopsin, absorbs visible light to initiate the visual signal transduction pathway.

Answer 12

Opsin

Question 13

the prosthetic group of rhodopsin that, upon absorbing light, undergoes an isomerization from 11-cis-retinal to all-trans-retinal, initiating the visual signal transduction pathway.

Answer 13

Retinal

Question 14

the photoreceptor of rod cells. It is composed of the protein opsin and the prosthetic group 11-cis-retinal.

Answer 14

Rhodopsin

Question 15

vertebrate photoreceptor cells that function in dim light but are color-insensitive.

Answer 15

Rod

Question 16

an alpha subunit of a G protein that is primarily expressed in taste buds and is

Answer 16

Gustducin

Question 17

specialized neurons inside the cochlea of inner ear. Hair cells use a connected bundle of stereocilia to detect motion and initiate the hearing signal transduction pathway.

Answer 17

hair cell

Question 18

an enzyme that catalyzes the synthesis of cGMP, a second messenger, from GTP.

Answer 18

guanylate cyclase

Question 19

a specialized neuron that transmits signals to pain-processing centers of the spinal cord and brain in response to the onset of tissue damage.

Answer 19

nociceptor

Question 20

Membrane proteins that detect odorants; one of the largest gene families in human beings.

Answer 20

odorant receptor

Question 21

G protein that is the signal coupling protein of visual excitation; transducin is activated by rhodopsin and leads to the activation of cGMP phosphodiesterase, which in turn leads to a nerve impulse.

Answer 21

Transducin

Question 22

one of a bundle of 20 to 300 hairlike projections that protrude from hair cells. Movements of a stereocilia initiate the hearing signal transduction pathway by altering the polarization of hair cells.

Answer 22

Sterocilium

Question 23

a filament that links adjacent stereocilia. Tip links are coupled to ion channels in the membranes of stereocilia that are gated by stress. Thus, mechanical movement is alters the current flow across a hair cell membrane, which may initiate or terminate the hearing signal transduction pathway.

Answer 23

tip link

Question 24

One of the five primary tastes that classifies compounds that are sometimes potentially harmful or toxic, perceived in the simplest tastant, the hydrogen ion.

Answer 24

sour

Question 25

One of the five primary tastes that classifies compounds into potentially nutritive and beneficial, perceived in simple ions, particularly the sodium ion.

Answer 25

salty

Question 26

One of the five primary tastes that classifies compounds into potentially nutritive and beneficial and perceived in diverse tastants such as carbohydrates.

Answer 26

sweet

Question 27

One of the five primary tastes that classifies compounds into potentially nutritive and beneficial. This is the taste of glutamate and aspartate from the Japanese word for “deliciousness.”

Answer 27

umami