PCB chapter 6

Which of the following statements about taste is true?

H+conveys sour, sugars convey sweet, amino acids convey umami

What defines a cell as an afferent neuron?

It has an axon that carries information to integrating centers.

__________ are a kind of receptor that respond to extremely strong stimuli, including those that may cause tissue damage.

Nociceptors

Which of the following choices is FALSE regarding rhabdomeric photoreception?

The absorption of light leads to cell hyperpolarization.

For sensory receptor cells, the "threshold of detection" is the weakest stimulus that produces

a response 50 percent of the time

What is true about the chromophore?

absorbs energy from photons, covalently linked to a member of opsin gene family, and plays a role in photoreceptor sensitivity to different colors, derivative of vit A

__________ send signals in the form of action potentials from periphery to integrating centers such as brain

afferent neurons

In the mammalian inner ear, inner hair cells detect sounds, while outer hair cells __________.

amplify sounds

In arthropods, the primary olfactory organs are generally located on the

antennae

Touch and pressure receptors can be broadly grouped into three categories: tactile receptors, proprioceptors, and __________.

baroreceptors

A thin piece of dome-shaped cuticle was found near one of the joints in a cricket leg. When it was removed, the animal could no longer make coordinated movements, but it could still respond to the rapid approach of a predator. This structure is most likely a

campaniform sensilla

The compound called __________ can stimulate warm-sensitive neurons.

capsaicin

Which of the following structures from the vertebrate inner ear is NOT part of the vestibular apparatus?

cochlea

Ruffini corpuscles are associated with __________ and detect __________.

connective tissue of skin; skin stretch

A tympanal organ functions as an insect __________

ear

In vertebrates, olfactory receptor cells are bipolar sensory neurons, but taste receptor cells are __________.

epithelial cells

___________ are single cells that contain a photosensitive pigment and a shading pigment that helps provide directional information by shading light coming from some directions.

eyespots

A polymodal sensory receptor encodes different modalities using labeled line processing.

false

Arthropods do not have external sensory structures because the hard exoskeleton prevents it.

false

Different sensory neurons use different types of action potentials to transmit information.

false

In vertebrates, each odorant receptor protein can bind only a single odorant.

false

Mechanoreceptors make use of G proteins to transduce mechanical signals into electrical ones.

false

Proprioceptors normally fire phasically.

false

Taste receptor proteins are always associated with G proteins.

false

The gustatory system can discriminate as many compounds as the olfactory system.

false

The vertebrate olfactory system can distinguish thousands of odorants through labeled line processing.

false

To focus on an object, the cornea must modify its shape to some extent.

false

Unicellular eukaryotes cannot respond to environmental stimuli.

false

Vertebrate tactile receptors are grouped into complex mechanosensory organs.

false

Weakly electric fish have organs to generate electrical discharge, but do not have electroreceptors.

false

It is generally held that ciliary photoreceptors are associated with invertebrates, while rhabdomeric photoreceptors are associated with vertebrates.

false (both can have both)

The vestibular, tympanic, and cochlear ducts of the mammalian inner ear are filled with a substance called perilymph.

false (only vestibular and tympanic, cochlear filled with endolymph)

In aquatic vertebrates, gustation always involves detecting sensations involved with

food (olfaction associated with food, predators, potential mates, and locations)

In both the ________ and _________ the overlying bipolar and ganglion cells are pushed to one side, allowing light to strike the photoreceptors without passing through several layers of neurons. This is where vision is sharpest.

fovea and visual streak

Stimulus intensity is normally coded by action potential __________.

frequency

When a sensory receptor is an afferent neuron, the membrane potential that is initiated by a stimulus is called a

generator potential

If the orientation of your ears were changed so that your right ear still faced forward but your left ear faced backward, how would your ability to locate the direction of an auditory stimulus change?

improved ability to distinguish front from back

Improving the resolving power of the compound eye would require

increase number of ommatidia or reduce the size of each ommatidium

Mechanoreceptors translate mechanical signals into electrical signals when pressure on the cell

induces a conformational change in ion channels, allowing ions to flow.

In response to a stimulus, a signal transduction pathway is initiated, which ultimately leads to the opening or closing of __________.

ion channels

Which eye structure constricts or dilates to control the amount of light that enters the eye?

iris

To help discriminate the location of a touch stimulus, neurons at the center of the receptive field can inhibit those at the edge, a process known as __________.

lateral inhibition

What are the three bones in the middle ear?

malleus incus stapes

Select the pair below that does not match.

mechanoreceptors- magnetic fields

The compound called __________ can stimulate cold-sensitive neurons.

menthol

In the vertebrate olfactory system, the olfactory receptor cells have one end in the olfactory epithelium, and the other end makes synapses with neurons in the __________ of the brain.

olfactory bulb

Compound eyes are composed of many __________.

ommatidia

The organ of the inner ear of mammals that contains the hair cells is called the __________.

organ of corti

The focal point is the

point where light waves converge after passing through the lens. (incoming light rays must converge at the retina, not behind it or in front in order to produce a clear image)

Sensory cells that respond to more than one class of stimulus are called __________ receptors.

polymodal

All sensory systems work in the same general way. They transduce an incoming stimulus into changes in membrane

potential

You are riding your bicycle over a very bumpy road, reading a street sign far ahead of you. Which sensory inputs are required to accomplish this task?

proprioceptors, visual inputs, inner ear

Odorant receptors are

proteins

________ is when the action potential frequency declines if the stimulus intensity is maintained at a constant level.

receptor adaptation

To generate an optimal visual image, the focal point must fall on the

retina

Which taste receptor does NOT use a G-protein-coupled receptor for activation?

salty

Merkel's disks are used by the visually impaired for reading Braille. One quality of the receptor that allows this is

small receptive field

In mammals, the circadian clock is located in the

suprachiasmatic nucleus.

What is the main difference between "on" and "off" region receptive fields?

the nature of the response of the bipolar cell to glutamate

Among vertebrates, taste buds share certain common features. Which of the following is FALSE?

they are single neurons TRUE: onion shaped, They have a pore that opens out to the surface of the body, and They have numerous microvilli on the apical surface.

A paramecium is capable of responding to

touch, chemicals, temperture

Bitter and sour tastes are generally associated with

toxic substances

Which of the following is one of the steps of sensory processing?

transduction of the signal, transmission of the signal to the integrating center, perception of the stimulus at the integrating center

There are two main types of mechanoreceptor proteins: epithelial sodium channels and __________.

transient receptor potential channels

A cup-shaped eye has improved discrimination in light direction and intensity over a flat sheet eye.

true

All vertebrates have an inner ear.

true

Bitter-taste receptors do not depolarize when activated.

true

Despite the great diversity of eye structure, there is surprising similarity at the molecular level in the development of eyes in all animals.

true

In Drosophila, each gustatory neuron appears to express only a single receptor protein.

true

In vertebrates, each odorant receptor cell expresses only a single kind of odorant receptor protein.

true

Many sensory receptor cells are epithelial cells.

true

Odor receptor proteins are always coupled to G proteins.

true

One similarity of all sensory receptors is that they must transduce some signal into a membrane potential.

true

Sensory processing requires the release of neurotransmitter.

true

The activity of hair cells in the vertebrate inner ear depends on a high concentration of extracellular K+.

true

The labeled line theory is based on the assumption that there is a discrete pathway from a sensory cell to the integrating center.

true

The minimum criterion for calling something an eye, rather than a photoreceptor, is the ability to detect the direction by which light has entered the organ.

true

Unlike taste receptor cells in vertebrates, invertebrate taste receptor cells are bipolar sensory neurons.

true

Vertebrate hearing and equilibrium require the activity of hair cells, so-called because of the cilia that extend from the apical end of each cell.

true

Terrestrial vertebrates detect pheromones using an organ called the __________ organ.

vomeronasal

The __________ law describes the logarithmic relationship between stimulus magnitude and perceived stimulus intensity.

weber-fechner