Auditory Physiology Flashcards

1
Q

What is sound?

A

Oscillations of air pressure

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2
Q

What is amplitude?

A

Sound pressure (intensity) measured in Decibels

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3
Q

What is frequency?

A

Number of oscillations of air pressure per second measured in Hz

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4
Q

Describe the properties of the basilar membrane?

A

It is narrow and STIFF near the oval/round windows

It is wider and FLEXIBLE near the apex (helicotrema)

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5
Q

Motion at the base of the basilar membrane is done by?

A

High pitched sounds (high frequencies)

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6
Q

Motion at the apical end of the basilar membrane is done by?

A

Low frequency (pitched) sounds

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7
Q

The frequency of sound is coded by?

A

Where along the basilar membrane there is the greatest DEFLECTION

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8
Q

High pitched sounds deflect the basilar membrane where?

A

Near the round/oval windows at its base

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9
Q

Low pitched sounds deflect the basilar membrane where?

A

Near the helicotrema near its apex

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10
Q

What type of receptors are hair cells?

A

Mechanoreceptors

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11
Q

Are hair cells neurons?

A

Nope

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12
Q

What exists on the apical surface of hair cells?

A

Stereocilia

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13
Q

What protein is within stereociliar?

A

Actin

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14
Q

What can be found at the basal end of stereociliar?

A

Afferent and efferent nerve fiber synapses

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15
Q

Levels of potassium and sodium in Endolymph?

A

HIGH K and low na

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16
Q

Levels of potassium and sodium in Perilymph?

A

LOW K and high na

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17
Q

Does endolymph or perilymph bath the apical surface of hair cells?

A
Endolymph = apical end
Perilymph = basal end
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18
Q

As the basilar membrane is deflected by sound, it moves the hair cells against the tectorial membrane. What way must the stereocilia be deflected in order to depolarize?

A

TOWARDS the tallest stereocilia

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19
Q

As the stereocilia at deflected towards the tallest one, what is opened?

A

Mechanically gated K+ channels and potassium enters cell

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20
Q

____ connects stereocilia and the force is transmitted to ______

A

Tip links

Elastic gating spring

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21
Q

Once potassium is allowed into hair cells, then what happens?

A

TRPA1 channels are opened and Ca++ enters the cell

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22
Q

What ions come into the hair cell to depolarize it and allow for NT release?

A

K and Ca

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23
Q

What neurotransmitter is released from hair cells?

A

Glutamate

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24
Q

If the stereocilia at deflected towards the smallest stereocilia, what happens?

A

Hyperpolarization

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25
Q

What produces endolymph?

A

Stria vascularis

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26
Q

Where is the stria vascularis?

A

In the scala media

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27
Q

As the stria vascularis produces endolymph (high in K+), what does this create for the scala media?

A

A resting membrane potential of +80 mv

28
Q

The potential of +80 mv in the scala media creates what?

A

Drives (+) ions down their conc. gradient into hair cells and creates a blood-Labyrinth Barrier (BLB)

29
Q

Any substance that crosses _____ can damage/impact hearing by hurting the stria vascularis?

A

BLB - blood labyrinth barrier

30
Q

Inner hair cells are?

A

Primary source of auditory info

31
Q

Inner hair cells are arranged into a ___ layer

A

single

32
Q

Outer hair cells act as?

A

An amplifier of sound

33
Q

Outer hair cells are arranged into ____ rows

A

3

34
Q

What property allows the outer hair cells to amplify sound?

A

They are contractile epithelial cells and when they contract, it further displaces the basilar membrane!

35
Q

When the ear itself produces sound it is known as?

A

Otoacoustic emissions (OAE)

36
Q

Describe how an ear can itself produce sound?

A

Impulses originate at the superior olivary complex

  • Olivocochlear efferents go to outer hair cells
  • Outer hair cells then contract and displace the basilar membrane which produces sound that travels back out middle hear and to tympanic membrane
37
Q

2 types of OAE

A

Spontaneous and Evoked

38
Q

Evoked OAE test?

A

Hearing loss on infants

- Evoked emissions will NOT be present if there is hearing loss

39
Q

Posterior cochlear nuclei

A

Integrates acoustic information with somatosensory

40
Q

Anterior cochlear nuclei

A

Begins processing temporal and spectral features of sound

41
Q

Medial superior olivary complex

A

Generates a map of interaural TIME differences to help localize location of sound

42
Q

Lateral superior olivary complex

A

Generates a map of interaural INTENSITY differences

43
Q

Inferior colliculus

A

Suppressed information related to echoes and creates a precise origin of sound location

44
Q

Medial geniculate nucleus

A

Relays all information about sound to the primary auditory cortex

45
Q

Primary auditory cortex

A

Conscious perception of sound

46
Q

What is the arrangement of the primary auditory cortex?

A

Rostral regions = low freq. sound

Caudal regions = high freq. sound

47
Q

What does the secondary auditory cortex respond to?

A

More complex sounds like music and identifying/naming a sound

48
Q

The secondary auditory cortex includes?

A

Broca’s and Wernicke’s areas

49
Q

What are the efferent innervations in the ear?

A

Olivocochlear, Middle ear muscle motoneurons, autonomic innervation of inner ear

50
Q

What do olivocochlear efferents do?

A

In response to LOUD noises, they decrease basilar membrane motion and protect hair cells

51
Q

What do middle ear muscle motoneurons do?

A

In response to LOUD noises, bilateral contraction to reduce transmission of sound and prevent damage

52
Q

What are the middle ear muscles?

A

Tensor tympani and stapedius

53
Q

What is the autonomic innervation of the inner ear comprised of?

A

Sympathetic adrenergic fibers

54
Q

What causes Sensorineural hearing loss?

A

Damage to hair cells or nerve fibers or both

55
Q

Which type of hair cell is more susceptible to injury?

A

Outer hair cells

56
Q

Damage to outer hair cells?

A

Decrease sensitivity to sound

57
Q

Damage to inner hair cells?

A

Cut off auditory input to CNS

58
Q

How to cochlear prostheses restore some hearing?

A

Electrode array threaded through cochlea and stimulates surviving nerve fibers

59
Q

Part of ear activated by forward motion

A

Anterior semi-circular canals

60
Q

Part of ear activated by backward motion

A

Posterior semi-circular canals

61
Q

Part of ear activated by rotation

A

Horizontal semi-circular canals

62
Q

Part of ear activated by linear acceleration forward and backward

A

Utricle

63
Q

Part of ear activated by linear acceleration up and down

A

Saccule

64
Q

What are the main structures that are involved in the pathway of sound processing?

A
Cochlear nuclei
Superior olivary complex
Inferior colliculus
Medial Geniculate nucleus
Primary auditory cortex
65
Q

What innervates outer hair cells?

A

Medial olivary complex neurons

66
Q

What innervates inner hair cells?

A

Lateral olivary complex neurons