Deck 24: Auditory and Vestibular Sensation

Question 1

The first structure to be disturbed by sound waves is the

A) stapes.
B) tympanic membrane.
C) oval window.
D) round window.
E) malleus.

Answer 1

B

Question 2

Propagating sound waves can be measured as changes in

A) volume.
B) pressure.
C) Force.
D) Electrical transmission.
E) Movement.

Answer 2

B

Question 3

Which two structures must change positions relative to each other in order for hair cells to be stimulated?

A) Cochlea and tectorial membrane
B) Endolymph and tectorial membrane
C) Basilar membrane and tectorial membrane
D) Basilar membrane and Reissner's membrane
E) Basilar membrane and scala vestibule

Answer 3

C

Question 4

Which two properties of the basilar membrane are responsible for the ability to discern among various sound frequencies?

A) Length and width
B) Length and depth
C) Length and thickness
D) Thickness and width
E) Thickness and depth

Question 5

The first part of the brain to receive afferent cochlear nerve inputs is the

A) lateral superior olivary nucleus.
B) medial superior olivary nucleus.
C) cochlear nuclei.
D) auditory cortex.
E) olivocochlear bundle.

Question 6

Each inner ear hair cell can send impulses to as many as ????_______ postsynaptic afferent fibers.

A) 5
B) 10
C) 20
D) 100
E) 1,000

Question 7

The stria vascularis is responsible for making the endolymph _______ with respect to cytoplasm.

A) hypertonic
B) isotonic
C) hypotonic
D) acidic
E) alkaline

Question 8

Which structure probably acts as a buffer against reverberating perilymph caused by sound waves?

A) Scala vestibule
B) Scala media
C) Round window
D) Basilar membrane
E) Tectorial membrane

Question 9

Outer hair cells outnumber inner hair cells by approximately

A) 100 to 1.
B) 10 to 1.
C) 5 to 1.
D) 3 to 1.
E) They are about equivalent in numbers.

Question 10

Which dendrites innervate inner hair cells?

A) Those of the auditory nerve
B) Those of the cochlear nucleus
C) Those of the superior olivary nucleus
D) Those of the outer hair cells
E) Those of the cochlear ganglion bundle

Question 11

Inner and outer hair cells differ with respect to

A) sensitivity and number.
B) location and number.
C) location and innervation patterns.
D) sensitivity.
E) sensitivity and neurotransmitters used.

Question 12

The inner hair cells are considered to be the primary sensory hair cells of the cochlea because they

A) lie along the central axis of the cochlea.
B) are fewer in number than outer hair cells; hence, they are more sensitive.
C) are in closer contact with the tectorial membrane than the outer hair cells are.
D) are much more densely innervated by afferent contacts.
E) have more hairs than outer hair cells do.

Question 13

The location of individual hair cells along the cochlear duct determines the _______ at which that sensory fiber responds.

A) intensity
B) frequency
C) innervation
D) energy
E) neurotransmitter amount

Question 14

Chronic exposure to extremely loud low-pitched noises (> 150 dB) are likely to destroy hair cells at (the) _______ of the cochlea.

A) apex
B) base
C) random locations along the length
D) center (where inner hair cells are located)
E) periphery (where outer hair cells are located)

Question 15

The tonotopic map starts in the basilar membrane of the cochlea and ends in the

A) lateral superior olive.
B) medial superior olive.
C) inferior colliculus.
D) medial geniculate nucleus (thalamus).
E) auditory cortex.

Question 16

To construct a series of tuning curves, which of the following experimental conditions is required?

A) Several different tones must be evaluated.
B) Tones used must be pure.
C) A range of different intensities must be used.
D) At least one high- and low-frequency tone must be used.
E) Intensities must all be the same at a given frequency.

Question 17

When constructing a series of tuning curves, the resulting frequency of action potentials depends on the _______ of each tone.

A) pitch
B) frequency
C) purity
D) origin
E) intensity (volume)

Question 18

Electromotility of outer hair cells is the mechanism of how the basilar membrane and Organ of Corti respond to different

A) frequencies.
B) tones.
C) types of pure tones.
D) types of mixed tones.
E) intensities.

Question 19

At cytoplasmic pH of ~ 7.2, prestin

A) is negatively charged.
B) is positively charged.
C) is both negatively and positively charged.
D) is an ion channel lined with negatively and positively charged amino acids.
E) changes charge, depending on whether the hair cell membrane is depolarized or hyperpolarized.

Question 20

Destruction of outer hair cells

A) has little to no effect on hearing because the inner hair cells are more important in sensory reception of sound.
B) enhances sensitivity of the inner hair cells.
C) decreases the threshold for hearing.
D) increases the threshold for hearing.
E) disrupts the ability to distinguish among different tones.

Question 21

If an outer hair cell is 50 µm long and undergoes a change in length of 2 µm, culminating in 30 nm/mV, what is the change in potential when the cell is depolarized?

A) 0.067 mV
B) 2 mV
C) 15 mV
D) 16.6 mV
E) 67 mV

Question 22

How are outer hair cells most likely inhibited by medial efferents?

A) Via cholinergically generated ipsps that lower the membrane potential through chloride influx
B) Via cholinergically generated ipsps that lower the membrane potential through a change in the driving force of potassium
C) Via cholinergiaclly generated ipsps that result in no production of second messenger (e.g., cAMP) through G_si (inhibitory G protein) GPCRs
D) Via GABAergic activation
E) Via inhibition of glutamatergic input

Question 23

With respect to its resonant frequency (220 Hz), why would the lower frequency (70 Hz) result in greater hyperpolarization (more inhibition) of outer hair cells?

A) Inhibition of neighboring outer hair cells contributes to the increased inhibition.
B) Lower tones (frequencies) are more difficult to detect, requiring a greater difference in membrane potential.
C) At lower frequencies, electromotility is inhibited.
D) Elongated outer hair cells mean that the greater membrane surface area exposes more cholinergic receptors.
E) Inner hair cells are inhibited through increased potassium conductance, driven by the Nernst equilibrium potential for potassium.

Question 24

What would be the best candidate to modify (mutate or knock-out) in transgenic mice in order to study various strengths of efferent inhibition of the cochlea?

A) Cholinergic receptor (subunits) at efferent synapses on to the outer hair cells
B) Stereocilia protetins, such as actin
C) Prestin
D) Potassium channels
E) Tubulin

Question 25

Sound entering the left ear is still perceived bilaterally in the auditory cortex, because of decussation by neurons originating in the

A) lateral superior olive.
B) medial superior olive.
C) medial nucleus of the trapezoidal body.
D) dorsal cochlear nucleus.
E) ventral cochlear nucleus.

Question 26

The main nucleus that makes the horizontal localization of sound possible is the

A) superior olivary complex.
B) neurons of the Trapezoidal body.
C) dorsal Cochlear nucleus.
D) ventral cochlear nucleus.
E) inferior colliculus.

Question 27

A loud noise (of mixed sounds) arriving at one side of the head enters the ipsilateral ear first and is slightly muffled as perceived via the contralateral ear. This is mostly because the

A) contralateral ear is farther away.
B) contralateral ear is protected by air pressure.
C) head absorbs some of the noise energy before it arrives at the contralateral ear.
D) head prevents much of the noise energy from getting through.
E) head slows down the speed of sound.

Question 28

How many times does the central auditory system decussate?

A) Once
B) Twice
C) Three times
D) Four times
E) There are no decussations

Question 29

Which other type of function or physiological phenomenon is the vestibular system most similar to?

A) Thinking (CNS)
B) Exertion (musculo-skeletal system)
C) Defense (immune system)
D) Nutrient transport (cardiovascular system)
E) Reflexes (autonomic nervous system)

Question 30

What is the function of the otoliths in the endolymph?

A) To increase viscosity of the endolymph
B) To increase the specific gravity of the endolymph
C) To increase the inertial dampening of the endolymph
D) To act as a reservoir of calcium, since this mineral/ion is so important for intracellular communication
E) No function-they are just calcium carbonate debris resulting from wear and tear of nearby boney structures.

Question 31

The utricle responds to

A) gravity.
B) rotation of the head.
C) only forward linear acceleration or deceleration of the head.
D) only backward linear acceleration or deceleration of the head.
E) both forward and backward linear acceleration and deceleration of the head.

Question 32

The semicircular canals respond to

A) any rotation of the head.
B) stationary head.
C) only nodding of the head.
D) both forward and backward linear acceleration.
E) changes in posture.

Question 33

Which of the following would stimulate the saccules?

A) Riding in a car travelling at a constant speed
B) Riding in an airplane traveling at a constant speed
C) Riding in an airplane as it accelerates during takeoff
D) Riding in an elevator as it slows down
E) Riding in an elevator midway through the ride, where its speed is constant

Question 34

When vestibular hair cells are stimulated, potassium from the endolymph rushes inward. What does this indicate about the potassium concentration in the endolymph relative to the cytoplasm?

A) It must be higher.
B) It must be lower.
C) It must be equal.
D) It varies depending on the whether the hair cell is Type I or Type II.
E) It depends on whether the stimulus is changes in velocity, rotation or gravity.

Question 35

Afferent firing rates are faster in Type II than in Type I vestibular hair cells because the former has

A) smaller soma, so that there is less membrane through which the potential must travel.
B) a calyx, which surrounds most of the soma.
C) larger axons.
D) heavier myelination.
E) larger axons and heavier myelination.

Question 36

Although both Type I and Type II vestibular hair cells release glutamate onto afferent endings and acetylcholine onto the Type II calyces and Type I soma, what determines whether efferent output is excitatory or inhibitory, everything else being equal (species, age, etc.)?

A) The amount of glutamate released
B) The amount of acetylcholine released
C) The type and amount of calcium channels used
D) The type and amount of potassium channels used
E) The type of cholinergic receptors used

Question 37

Depolarizations of vestibular hair cells depends on activation of

A) sodium channels.
B) potassium channels.
C) calcium channels.
D) both sodium and calcium channels.
E) both sodium and potassium channels.

Question 38

Whether movement is accelerating or decelerating, upright or upside down, oriented in any other direction, even in the absence of visual clues, we can still determine our orientation in three-dimensional space because

A) at least one pair of semicircular canals (one in each ear) will always be stimulated.
B) all three pairs of semicircular canals will always be stimulated to some extent.
C) each semicircular canal in each side of the head are set at right angles to each other.
D) otolith crystals are able to flow freely from one semicircular canal to another, depending on the direction and speed of movement.
E) endolymph preferentially bends the stereocilia in one direction to depolarize or in the opposite direction to hyperpolarize.

Question 39

The purpose of the vestibulo-ocular reflex is

A) so that one is able to maintain and upright posture.
B) so that one is able to walk or run without falling.
C) for survival, so that potential threats (e.g., a mugger) and needs (e.g., food, mating partners) can be visually tracked.
D) for supplementing the visual system.
E) for supplementing the auditory system.

Question 40

Why do some people have trouble reading while in a moving vehicle?

A) The vestibulo-ocular reflex does not work in a moving vehicle.
B) The muscles that move the eye do not stabilize the eye enough, even when the head is moving just a little.
C) A moving vehicle is too dynamic for the vestibule-ocular reflex to adapt to.
D) Utricle activity overrides the vestibule-ocular reflex.
E) Conscious visual fixation on a stationary object (e.g., printed material) does not invoke the vestibulo-ocular reflex.

Question 41

The ability to maintain posture in any conscious physical movement, such as walking or running, is modulated by

A) saccules.
B) lateral and medial rectus muscles of the eyes.
C) third and sixth cranial nerve nuclei.
D) deep cerebellar vestibular nuclei.
E) the vestibulo-ocular reflex.

Question 42

For sound(s) to be meaningful (e.g., speech), what must happen after action potentials have arrived at the auditory cortex?

Question 43

What is the exact point at which mechanical energy is transformed into electrical/chemical energy?

Question 44

Diagram or describe how outer hair cells and inner hair cells are arranged in the cochlea.

Question 45

One type of tone-deafness is known as amusia and is being unable to sing in tune. Suggest a possible reason.

Question 46

Explain how electromotility of outer hair cells fine-tune the activity of inner hair cells.

Question 47

Calculate the amount of longitudinal force required to decrease the length of an outer hair cell from 40 to 39 µm, where longitudinal force is 0.1 nN/µm.

Question 48

If an outer hair cell is 40 µm long at rest, (A) how long will it be when depolarized by 100 mV? (B) How much force will be required for this to happen? Assume that the length change is 30 nm/mV.

Question 49

Explain how feedback inhibition is frequency-specific.

Question 50

Propose a possible cause of tinnitus.

Question 51

Describe how we locate the origin of a sound horizontally.

Question 52

What scenario comes closest to being completely devoid of vestibular functioning?

Question 53

Why are we shielded from the sensation of forward movement in a moving vehicle?

Question 54

How is the membrane potential changed when head movement stimulates vestibular hair cells?

Question 55

What are the three neurons in the circuit controlling the vestibular-ocular reflex?

Question 56

Propose one potentially critical function that the vestibular system plays in autonomic homeostasis.