Chapter 14 Sample Questions

1. After stereocilia move toward the kinocilium,
a. mechanically-gated channels close.
b. the hair cell hyperpolarizes.
c. there is an efflux of calcium.
d. there is a decreased release of transmitter from the hair cell.
e. there is increased signaling in the vestibular nerve.

e

2. Why is it important that transduction channels are open at rest?
a. To maintain separation of perilymph and endolymph
b. To allow hair cells to signal both increases and decreases
c. To permit movement of stereocilia in either direction
d. So that transmitter is released only when stereocilia move toward the kinocilium
e. To facilitate vestibular nerve firing in only when the head changes position

b

3. What type of movement do the saccule and utricle respond to, respectively?
a. Vertical; rotational
b. Vertical; horizontal
c. Rotational; vertical
d. Horizontal; vertical
e. Horizontal; rotational

B

6. If a person tilted their head downward to tie their shoes and then straightened their head up again, firing rate of the vestibular nerve would
a. increase and remain increased while the person was tying their shoes.
b. increase only during the initial downward tilt of the head.
c. decrease and remain decreased while the person was tying their shoes.
d. decrease only during the initial downward tilt of the head.
e. decrease during the initial downward tilt of the head and then increase as the head straightened back up.

C

7. Like many of our other senses, vestibular percepts integrate additional sensory information. The loss of which sense would most affect perception?
a. Taste
b. Smell
c. Hearing
d. Vision
e. Touch

D

8. Refer to the figure.

*PAGE 16

You are measuring firing rate from a vestibular axon that innervates a hair cell in the utricle (top left panel, leftmost hair cell). What should happen to the firing rate when the subjects tilt their head forward (right top panel)?
a. A
b. B
c. C
d. D
e. E

E

1. In what ways are the vestibular and auditory sense organs similar?

Answer: Both the vestibular and auditory system have elaborate set of interconnected chambers that use endolymph movement and specialized hair cells to detect stimuli.

2. How do the saccule and utricle detect different directions of head tilts and translational motion?

Answer: They detect different directional movement because the saccules are oriented vertically, while the utricles are oriented horizontally. Additionally, hair cell populations are divided in two by the striola within each saccule and utricle.

3. Explain how the semicircular canals are specialized to assess rotational acceleration of the head, whereas the otolith organs are specialized to detect linear acceleration and static position of the head relative to the gravitational axis.

Answer: The semicircular canals lay in different planes within each side of the head. The hair cells in the ampulla of each semicircular canal have only one orientation. Each semicircular canal works in concert with its partner, located on the other side of the head, with its hair cells oppositely aligned. When the head rotates, the cupula within the semicircular canal in the plane of rotation increase firing rate on one side and decrease firing rate on the other side. This partnership results in information about head rotation in any direction. The striola in the otolith organs creates an axis of symmetry within each organ. Thus, firing will increase on one side of the organ while it decreases in the other. The utricle and saccule are oriented in different planes to allow the head detect head tilts and translational movements in different directions.

4. What symptoms indicate damage to the vestibular system?

Answer: The common symptoms of vestibular damage include poor balance, diminished head and postural stability, gait deviations, altered perception of personal and extrapersonal space, difficulty visually fixating on an object while the head moves, and altered slow and fast eye movements when the head rotates.