Exam Questions Chapter 24 Auditory And Vestibular Sensation

Chapter 24: Auditory and Vestibular Sensation

Test Bank

Type: multiple choice question

Title: Chapter 24 Question 01

1. The first structure to be disturbed by sound waves is the

Feedback: Subhead: The Auditory System

Learning Objective: Explain, in basic terms, how the auditory system transduces sound waves that enter the outer ear into meaningful signals in the auditory cortex.

Bloom’s Level: 2. Understanding

a. stapes.

b. tympanic membrane.

c. oval window.

d. round window.

e. malleus.

Type: multiple choice question

Title: Chapter 24 Question 02

2. Propagating sound waves can be measured as changes in

Feedback: Subhead: The Auditory System

Learning Objective: Explain, in basic terms, how the auditory system transduces sound waves that enter the outer ear into meaningful signals in the auditory cortex.

Bloom’s Level: 3. Applying

a. volume.

b. pressure.

c. Force.

d. Electrical transmission.

e. Movement.

Type: multiple choice question

Title: Chapter 24 Question 03

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

Feedback: Subhead: The Auditory System

Learning Objective: Explain, in basic terms, how the auditory system transduces sound waves that enter the outer ear into meaningful signals in the auditory cortex.

Bloom’s Level: 1. Remembering

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

Type: multiple choice question

Title: Chapter 24 Question 04

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

Feedback: Subhead: The Auditory System

Learning Objective: Explain, in basic terms, how the auditory system transduces sound waves that enter the outer ear into meaningful signals in the auditory cortex.

Bloom’s Level: 1. Remembering

a. Length and width

b. Length and depth

c. Length and thickness

d. Thickness and width

e. Thickness and depth

Type: multiple choice question

Title: Chapter 24 Question 05

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

Feedback: Subhead: The Auditory System

Learning Objective: Explain, in basic terms, how the auditory system transduces sound waves that enter the outer ear into meaningful signals in the auditory cortex.

Bloom’s Level: 1. Remembering

a. lateral superior olivary nucleus.

b. medial superior olivary nucleus.

c. cochlear nuclei.

d. auditory cortex.

e. olivocochlear bundle.

Type: multiple choice question

Title: Chapter 24 Question 06

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

Feedback: Subhead: The Auditory System

Learning Objective: Name the sensory structures of the vertebrate inner ear.

Bloom’s Level: 1. Remembering

a. 5

b. 10

c. 20

d. 100

e. 1,000

Type: multiple choice question

Title: Chapter 24 Question 07

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

Feedback: Subhead: The Auditory System

Learning Objective: Name the sensory structures of the vertebrate inner ear.

Bloom’s Level: 3. Applying

a. hypertonic

b. isotonic

c. hypotonic

d. acidic

e. alkaline

Type: multiple choice question

Title: Chapter 24 Question 08

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

Feedback: Subhead: The Auditory System

Learning Objective: Name the sensory structures of the vertebrate inner ear.

Bloom’s Level: 3. Applying

a. Scala vestibule

b. Scala media

c. Round window

d. Basilar membrane

e. Tectorial membrane

Type: multiple choice question

Title: Chapter 24 Question 09

9. Outer hair cells outnumber inner hair cells by approximately

Feedback: Subhead: The Auditory System

Learning Objective: Discuss the similarities and differences between the inner and outer hair cells of the cochlea.

Bloom’s Level: 4. Analyzing

a. 100 to 1.

b.10 to 1.

c. 5 to 1.

d. 3 to 1.

e. They are about equivalent in numbers.

Type: multiple choice question

Title: Chapter 24 Question 10

10. Which dendrites innervate inner hair cells?

Feedback: Subhead: The Auditory System

Learning Objective: Discuss the similarities and differences between the inner and outer hair cells of the cochlea.

Bloom’s Level: 4. Analyzing

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

Type: multiple choice question

Title: Chapter 24 Question 11

11. Inner and outer hair cells differ with respect to

Feedback: Subhead: The Auditory System

Learning Objective: Discuss the similarities and differences between the inner and outer hair cells of the cochlea.

Bloom’s Level: 1. Remembering

a. sensitivity and number.

b. location and number.

c. location and innervation patterns.

d. sensitivity.

e. sensitivity and neurotransmitters used.

Type: multiple choice question

Title: Chapter 24 Question 12

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

Feedback: Subhead: The Auditory System

Learning Objective: Discuss the similarities and differences between the inner and outer hair cells of the cochlea.

Bloom’s Level: 2. Understanding

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.

Type: multiple choice question

Title: Chapter 24 Question 13

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

Feedback: Subhead: The Auditory System

Learning Objective: Explain how the basilar membrane contributes to frequency selectivity.

Bloom’s Level: 1. Remembering

a. intensity

b. frequency

c. innervation

d. energy

e. neurotransmitter amount

Type: multiple choice question

Title: Chapter 24 Question 14

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

Feedback: Subhead: The Auditory System

Learning Objective: Explain how the basilar membrane contributes to frequency selectivity.

Bloom’s Level: 5. Evaluating

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)

Type: multiple choice question

Title: Chapter 24 Question 15

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

Feedback: Subhead: The Auditory System

Learning Objective: Explain how the basilar membrane contributes to frequency selectivity.

Bloom’s Level: 4. Analyzing

a. lateral superior olive.

b. medial superior olive.

c. inferior colliculus.

d. medial geniculate nucleus (thalamus).

e. auditory cortex.

Type: multiple choice question

Title: Chapter 24 Question 16

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

Feedback: Subhead: The Auditory System

Learning Objective: Explain what a tuning curve is.

Bloom’s Level: 3. Applying

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.

Type: multiple choice question

Title: Chapter 24 Question 17

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

Feedback: Subhead: The Auditory System

Learning Objective: Explain what a tuning curve is.

Bloom’s Level: 4. Analyzing

a. pitch

b. frequency

c. purity

d. origin

e. intensity (volume)

Type: multiple choice question

Title: Chapter 24 Question 18

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

Feedback: Subhead: The Auditory System

Learning Objective: Discuss how electromotility of outer hair cells enhances cochlear tuning.

Bloom’s Level: 4. Analyzing

a. frequencies.

b. tones.

c. types of pure tones.

d. types of mixed tones.

e. intensities.

Type: multiple choice question

Title: Chapter 24 Question 19

19. At cytoplasmic pH of ~ 7.2, prestin

Feedback: Subhead: The Auditory System

Learning Objective: Discuss how electromotility of outer hair cells enhances cochlear tuning.

Bloom’s Level: 3. Applying

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.

Type: multiple choice question

Title: Chapter 24 Question 20

20. Destruction of outer hair cells

Feedback: Subhead: The Auditory System

Learning Objective: Discuss how electromotility of outer hair cells enhances cochlear tuning.

Bloom’s Level: 2. Understanding

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.

Type: multiple choice question

Title: Chapter 24 Question 21

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?

Feedback: Subhead: The Auditory System

Learning Objective: Discuss how electromotility of outer hair cells enhances cochlear tuning.

Bloom’s Level: 4. Analyzing

a. 0.067 mV

b. 2 mV

c. 15 mV

d. 16.6 mV

e. 67 mV

Type: multiple choice question

Title: Chapter 24 Question 22

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

Feedback: Subhead: The Auditory System

Learning Objective: Explain how efferent feedback from the central nervous system affects hair cell sensitivity and frequency selectivity in the inner ear.

Bloom’s Level: 6. Creating

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

Type: multiple choice question

Title: Chapter 24 Question 23

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?

Feedback: Subhead: The Auditory System

Learning Objective: Explain how efferent feedback from the central nervous system affects hair cell sensitivity and frequency selectivity in the inner ear.

Bloom’s Level: 4. Analyzing

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.

Type: multiple choice question

Title: Chapter 24 Question 24

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?

Feedback: Subhead: The Auditory System

Learning Objective: Explain how efferent feedback from the central nervous system affects hair cell sensitivity and frequency selectivity in the inner ear.

Bloom’s Level: 6. Creating

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

Type: multiple choice question

Title: Chapter 24 Question 25

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

Feedback: Subhead: The Auditory System

Learning Objective: Explain how the auditory system computes the localization of sound.

Bloom’s Level: 2. Understanding

a. lateral superior olive.

b. medial superior olive.

c. medial nucleus of the trapezoidal body.

d. dorsal cochlear nucleus.

e. ventral cochlear nucleus.

Type: multiple choice question

Title: Chapter 24 Question 26

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

Feedback: Subhead: The Auditory System

Learning Objective: Explain how the auditory system computes the localization of sound.

Bloom’s Level: 3. Applying

a. superior olivary complex.

b. neurons of the Trapezoidal body.

c. dorsal Cochlear nucleus.

d. ventral cochlear nucleus.

e. inferior colliculus.

Type: multiple choice question

Title: Chapter 24 Question 27

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

Feedback: Subhead: The Auditory System

Learning Objective: Explain how the auditory system computes the localization of sound.

Bloom’s Level: 3. Applying

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.

Type: multiple choice question

Title: Chapter 24 Question 28

28. How many times does the central auditory system decussate?

Feedback: Subhead: The Auditory System

Learning Objective: Explain how the auditory system computes the localization of sound.

Bloom’s Level: 3. Applying

a. Once

b. Twice

c. Three times

d. Four times

e. There are no decussations

Type: multiple choice question

Title: Chapter 24 Question 29

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

Feedback: Subhead: The Vestibular System

Learning Objective: Explain why vestibular function is sometimes referred to as “the silent sense”.

Bloom’s Level: 3. Applying

a. Thinking (CNS)

b. Exertion (musculo-skeletal system)

c. Defense (immune system)

d. Nutrient transport (cardiovascular system)

e. Reflexes (autonomic nervous system)

Type: multiple choice question

Title: Chapter 24 Question 30

30. What is the function of the otoliths in the endolymph?

Feedback: Subhead: The Vestibular System

Learning Objective: Name the structures of the vestibular system that detect angular motion of the head and linear acceleration.

Bloom’s Level: 1. Remembering

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.

Type: multiple choice question

Title: Chapter 24 Question 31

31. The utricle responds to

Feedback: Subhead: The Vestibular System

Learning Objective: Name the structures of the vestibular system that detect angular motion of the head and linear acceleration.

Bloom’s Level: 2. Understanding

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.

Type: multiple choice question

Title: Chapter 24 Question 32

32. The semicircular canals respond to

Feedback: Subhead: The Vestibular System

Learning Objective: Name the structures of the vestibular system that detect angular motion of the head and linear acceleration.

Bloom’s Level: 2. Understanding

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.

Type: multiple choice question

Title: Chapter 24 Question 33

33. Which of the following would stimulate the saccules?

Feedback: Subhead: The Vestibular System

Learning Objective: Name the structures of the vestibular system that detect angular motion of the head and linear acceleration.

Bloom’s Level: 3. Applying

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

Type: multiple choice question

Title: Chapter 24 Question 34

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?

Feedback: Subhead: The Vestibular System

Learning Objective: Describe the two types of vestibular hair cells.

Bloom’s Level: 3. Applying

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.

Type: multiple choice question

Title: Chapter 24 Question 35

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

Feedback: Subhead: The Vestibular System

Learning Objective: Describe the two types of vestibular hair cells.

Bloom’s Level: 3. Applying

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.

Type: multiple choice question

Title: Chapter 24 Question 36

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.)?

Feedback: Subhead: The Vestibular System

Learning Objective: Describe the two types of vestibular hair cells.

Bloom’s Level: 3. Applying

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

Type: multiple choice question

Title: Chapter 24 Question 37

37. Depolarizations of vestibular hair cells depends on activation of

Feedback: Subhead: The Vestibular System

Learning Objective: Describe the two types of vestibular hair cells.

Bloom’s Level: 3. Applying

a. sodium channels.

b. potassium channels.

c. calcium channels.

d. both sodium and calcium channels.

e. both sodium and potassium channels.

Type: multiple choice question

Title: Chapter 24 Question 38

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

Feedback: Subhead: The Vestibular System

Learning Objective: Explain what the vestibulo-ocular reflex is and why it is such an important mechanism.

Bloom’s Level: 4. Analyze

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.

Type: multiple choice question

Title: Chapter 24 Question 39

39. The purpose of the vestibulo-ocular reflex is

Feedback: Subhead: The Vestibular System

Learning Objective: Explain what the vestibulo-ocular reflex is and why it is such an important mechanism.

Bloom’s Level: 3. Applying

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.

Type: multiple choice question

Title: Chapter 24 Question 40

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

Feedback: Subhead: The Vestibular System

Learning Objective: Explain what the vestibulo-ocular reflex is and why it is such an important mechanism.

Bloom’s Level: 3. Applying

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.

Type: multiple choice question

Title: Chapter 24 Question 41

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

Feedback: Subhead: The Vestibular System

Learning Objective: Name three basic functions for which vestibular functions is essential.

Bloom’s Level: 2. Understanding

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.

Type: essay/short answer question

Title: Chapter 24 Question 42

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

Feedback: Like the visual cortex, meaning cannot be extracted if information simply terminates at the cortical target area (visual cortex, auditory cortex). Rather, to be able to make sense of the sound, such as someone speaking to you, the auditory cortex, in turn, must send projections to the pre-frontal cortex (for planning and interpretation), posterior parietal cortex (for localization), and to the speech centers (for identification) to verbally respond.

Subhead: The Auditory System

Learning Objective: Explain, in basic terms, how the auditory system transduces sound waves that enter the outer ear into meaningful signals in the auditory cortex.

Bloom’s Level: 3. Applying

Type: essay/short answer question

Title: Chapter 24 Question 43

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

Feedback: The shearing of hair cells between the basilar and tectorial membranes.

Subhead: The Auditory System

Learning Objective: Explain, in basic terms, how the auditory system transduces sound waves that enter the outer ear into meaningful signals in the auditory cortex.

Bloom’s Level: 3. Applying

Type: essay/short answer question

Title: Chapter 24 Question 44

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

Feedback: Inner hair cells lie close to the center, in a single row, along the length of the cochlea. Outer hair cells are arranged in three parallel rows closer to the periphery along the length of the cochlea.

Subhead: The Auditory System

Learning Objective: Discuss the similarities and differences between the inner and outer hair cells of the cochlea.

Bloom’s Level: 3. Applying

Type: essay/short answer question

Title: Chapter 24 Question 45

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

Feedback: It is well known that although the left hemisphere controls language, the right hemisphere controls the ability to sing. It is possible that the fibers that link the right temporal (hearing) and frontal (voluntary movement and expressive functions) lobes, known as the arcuate fasciculus, is smaller or malformed in some way, compared to those who can carry a tune.

Subhead: The Auditory System

Learning Objective: Explain what a tuning curve is.

Bloom’s Level: 6. Creating

Type: essay/short answer question

Title: Chapter 24 Question 46

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

Feedback: Although the vast majority (95%) of afferent fibers synapse with inner hair cells, this is not the only input they receive. Besides being stimulated directly by the sheering forces exerted by the basilar and tectorial membranes, inner hair cells are also affected by electromotility of outer hair cells which adds additional mechanical vibrations to the inner hair cells, whose stereocilia, therefore, are deflected even more. Moreover, prolonged inhibitory hyperpolarizations result in sustained elongated outer hair cells, which can increase the distance between the tectorial and basilar membranes, thereby decreasing the sheering forces, and, therefore, the stimulation, to which inner hair cells would be subjected. Thus, the threshold, sensitivity and tuning of cochlear afferent neurons is likewise decreased.

Subhead: The Auditory System

Learning Objective: Discuss how electromotility of outer hair cells enhances cochlear tuning.

Bloom’s Level: 2. Understanding

Type: essay/short answer question

Title: Chapter 24 Question 47

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.

Feedback: 1 µm x 0.1 nN/µm = 0.1 nN.

Subhead: The Auditory System

Learning Objective: Discuss how electromotility of outer hair cells enhances cochlear tuning.

Bloom’s Level: 3. Applying

Type: essay/short answer question

Title: Chapter 24 Question 48

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.

Feedback: (A) 100 mV x 30 nm/mV = 3,000 nm = 3 µm.

40 µm – 3 µm = 37 µm will be the new length.

(B) 37 µm x 0.1nN/µm = 0.3 nN will be required to achieve this.

Subhead: The Auditory System

Learning Objective: Discuss how electromotility of outer hair cells enhances cochlear tuning.

Bloom’s Level: 3. Applying

Type: essay/short answer question

Title: Chapter 24 Question 49

49. Explain how feedback inhibition is frequency-specific.

Feedback: Feedback or efferent inhibition means that the cochlea is inhibited at any given frequency. This is caused by activity of the nicotinic acetylcholine receptor, which is a non-specific ion channel, allowing sodium and calcium to enter the cell, in turn, resulting in activation of calcium-dependent potassium channels, allowing potassium to exit, leading to a deep and sustained hyperpolarization. This inhibition suppresses the cochlea response at a given frequency in case the intensity (volume) is too high. This mechanism, therefore, protects delicate hair cells in case the sound is too loud.

Subhead: The Auditory System

Learning Objective: Explain how efferent feedback from the central nervous system affects hair cell sensitivity and frequency selectivity in the inner ear.

Bloom’s Level: 2. Understanding

Type: essay/short answer question

Title: Chapter 24 Question 50

50. Propose a possible cause of tinnitus.

Feedback: Very little is known about this common debilitating condition in which the patient (imagines) that (s)he hears a high-pitched siren, ringing, whistle, etc. in the ears. This sound can vary in intensity from moment to moment, although the pitch is often relatively stable. Chief among what is not known is the cause. However, one prevailing hypothesis is that the condition is caused by bent, broken or dislodged hairs on inner and outer hair cells. Such damage can cause inadvertent leaking of potassium into the cells, over-stimulating them, and sending this message to the auditory cortex, which is perceived as sound. In addition, it is not known why high-pitched, rather than lower-pitched sounds are usually heard, except that perhaps because the surface area of the basilar membrane is so much larger at the apex (where high-pitched sounds are perceived) than at the base, there is greater probability of such damage occurring there. The cause of severe tinnitus can also be located centrally in which, perhaps, there is compromised feedback inhibition from the olivary complexes, due, perhaps, to aging, trauma, infection, or stroke.

Subhead: The Auditory System

Learning Objective: Explain how efferent feedback from the central nervous system affects hair cell sensitivity and frequency selectivity in the inner ear.

Bloom’s Level: 6. Creating

Type: essay/short answer question

Title: Chapter 24 Question 51

51. Describe how we locate the origin of a sound horizontally.

Feedback: For the sake of simplicity, describe the pathways unilaterally, say, starting on the left side: Depending on the frequency, neurons in the ventral cochlear nucleus will send axons to the contralateral side (right side) via the trapezoid body. Neurons in the left cochlear nucleus responding to low frequencies will send their axons monosynaptically into the right medial superior olivary nucleus, whereas ventral cochlear neurons responding to high frequencies will send their axons disynaptically into the right nucleus of the trapezoidal body: first to an inhibitory inter-neuron, which then makes a second synaptic inhibitory contact with neurons in the right lateral superior olivary nucleus. On the contralateral (right) side, in response to low-frequency sounds, the right ventral cochlear nucleus will make monosynaptic contact with the right medial superior olivary nucleus, whereas high-frequency sounds will be carried to the right lateral superior olivary nucleus. Both the medial and lateral superior olivary nuclei will then send axons up to the inferior colliculus. In addition, low-frequency sounds do not activate the two ears simultaneously: This time lag is known as the interaural time difference, which is greater as the sound originates farther away from the midline. For high-frequency sounds, the interaural time difference is insignificant. However, the head can muffle, thereby softening such sounds when approaching a distant ear. Thus, because high-frequency sound is hidden by the head, it is perceived to be milder from the perspective of the more distant ear. This is known as the interaural intensity difference.

Subhead: The Auditory System

Learning Objective: Explain how the auditory system computes the localization of sound.

Bloom’s Level: 3. Applying

Type: essay/short answer question

Title: Chapter 24 Question 52

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

Feedback: There is probably no instance during normal natural functioning in which the vestibular system is not working. Virtually every activity requires a working vestibular system, whether consciously or subconsciously, even during sleep. Probably, the closest scenario of when the vestibular system is not working is unconsciousness, such as by a trauma or drug-induced, or coma.

Subhead: The Vestibular System

Learning Objective: Explain why vestibular function is sometimes referred to as “the silent sense.”

Bloom’s Level: 3. Applying

Type: essay/short answer question

Title: Chapter 24 Question 53

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

Feedback: The utricle, like the saccule and semicircular canals, are sensitive only to changes in movement, but not to constant movement; thus, linear acceleration with your eyes closed is still a stimulus, as long as the acceleration continually changes.

Subhead: The Vestibular System

Learning Objective: Name the structures of the vestibular system that detect angular motion of the head and linear acceleration.

Bloom’s Level: 3. Applying

Type: essay/short answer question

Title: Chapter 24 Question 54

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

Feedback: Bending of the stereocilia towards the single taller kinocilium activates potassium transducer channels, allowing potassium to enter down its concentration gradient, which then depolarizes the cell membrane (although perhaps not to threshold) and which, in turn, activate voltage-gated potassium channels to allow more potassium to enter, leading to action potentials. These then cause the release of glutamate onto afferent endings.

Subhead: The Vestibular System

Learning Objective: Describe the two types of vestibular hair cells.

Bloom’s Level: 2. Understanding

Type: essay/short answer question

Title: Chapter 24 Question 55

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

Feedback: The vestibular nuclei, ipsilateral oculomotor nucleus (III) for moving the ipsilateral medial rectus of the eye and the contralateral abducens nucleus (VI) for moving the contralateral lateral rectus of the eye.

Subhead: The Vestibular System

Learning Objective: Explain what the vestibulo-ocular reflex is and why it is such an important mechanism.

Bloom’s Level: 2. Understanding

Type: essay/short answer question

Title: Chapter 24 Question 56

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

Feedback: Unconscious awareness of posture is mediated by the vestibular system. For example, in people who suffer from cardiovascular disease, such as high blood pressure, it is much more beneficial for the patient to sleep on his/her left side, so that venous return to the heart is not impeded by the weight of the body, which would occur if the person slept on the right side.

Subhead: The Vestibular System

Learning Objective: Name three basic functions for which vestibular input is essential.

Bloom’s Level: 6. Creating