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Neuroendocrine Part III > Physiology of the Auditory and Vestibular System > Flashcards

Physiology of the Auditory and Vestibular System Flashcards

1
Q

What are the physical properties of the basilar membrane at its base near the oval and round windows?

A
  • narrow

- stiff

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2
Q

What are the physical properties of the basilar membrane at its apex near the helicotrema?

A
  • wide

- flexible

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3
Q

Where do high frequency sounds create the greatest deflection along the basilar membrane?

A

-near the base where it’s narrow and stiff

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4
Q

Where do low frequency sounds create the greatest deflection along the basilar membrane?

A

-near the apex where it’s wide and flexible

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5
Q

Define tonotopy.

A
  • distinct locations along the basilar membrane within the inner ear interpret distinct frequencies
  • analogous to somatotopy of the motor and sensorimotor cortices
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6
Q

Explain the relationship b/w the hair cells, the tectorial membrane and the basilar membrane.

A
  • stereocilia of the hair cells are embedded in the tectorial membrane
  • body of the hair cells rest on the basilar membrane
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7
Q

List the steps that lead to the cochlear N. being stimulated due to upward displacement of the basilar membrane.

A
  • lateral displacement of sterocilia (tips stretch)
  • TRPA1 channels open (mechanotransduction)
  • K+ influx and depolarization
  • voltage-gated Ca channels open
  • glutamate-filled vesicles released
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8
Q

What happens if the basilar membrane is displaced downward?

A

-hyperpolarization

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9
Q

What does the stria vascularis create?

A

-endolymph

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10
Q

Endolymph has a high concentration of what ion?

A

-potassium

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11
Q

How is the potassium transported from the capillaries into the endolymph?

A
  • stria vascularis extends cytoplasmic processes around the capillaries to take in the released potassium
  • “intraepithelial plexus” exists that carries this out
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12
Q

What does the high endocochlear concentration of K+ aid in creating?

A
  • Blood-Labyrinth Barrier

- positive ions are driven down their concentration gradient into the hair cells

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13
Q

What is a main way for drugs to get into the hair cells?

A

-Blood-Labyrinth Barrier

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14
Q

If a drug disrupts the function of the stria vascularis, how would that lead to hearing loss?

A
  • less K+ in the endolymph means less K+ that can flow into the hair cells to depolarize them
  • less Ca channels open, which means less glutamate-filled vesicles are released (cochlear N. not stimulated)
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15
Q

What is the purpose of the outer hair cells?

A

-amplify sound and cause mvmt of basilar membrane

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16
Q

How many rows of outer hair cells are there?

A

-three

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17
Q

What do outer hair cells synapse with?

A
  • peripheral sensory afferent from spiral ganglion

- terminals from efferent neurons

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18
Q

What is the purpose of inner hair cells?

A

-primary source of auditory information

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19
Q

How many layers of inner hair cells are there?

A

-one

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20
Q

What do inner hair cells synapse with?

A
  • peripheral terminal of primary afferent sensory

- efferent neurons for activity modulation

21
Q

What are otoacoustic emissions?

A
  • when outer hair cells move retrograde toward oval window and moves the ossicles, causing displacement of the tympanic membrane from the interior
  • aka … the ear itself produces a sound
22
Q

What are otoacoustic emissions useful for?

A

-newborn hearing screening

23
Q

How do olivocochlear efferents protect the cochlea during intense sounds?

A
  • reduce electromotility of outer hair cells, thus decreasing basilar membrane motion
  • in turn, this reduces responses of inner hair cells and auditory nerve fibers
24
Q

How muscles does the middle ear use to protect the cochlea by attenuating intense sounds?

A
  • tensor tympani M. (connected to malleus and the tympanic membrane) (innervated by CN V)
  • stapedius M. (connected to stapes) (innervated by CN VII
25
Q

How do autonomic efferents protect the cochlea during intense sounds?

A
  • regulates vasculature tone in blood supply to cochlea
  • arise from CN VIII
  • sympathetic adrenergic fibers
26
Q

What is the role of the dorsal (posterior) cochlear nucleus in auditory processing?

A

-integrates acoustic info w/ somatosensory info

27
Q

What is the role of the ventral (anterior) cochlear nucleus in auditory processing?

A

-begins processing the temporal and spectral features of the sound

28
Q

What kind of input is received by the medial and lateral superior olivary complexes?

A

-excitatory glutamatergic

29
Q

Is the tonotopic map maintained in the medial and lateral superior olivary complexes?

A

Yes

30
Q

What is the role of the medial superior olivary complex in auditory processing?

A

-generates a map of interaural TIME differences in order to localize sound

(M-edial … ti-M-e)

31
Q

What is the role of the lateral superior olivary complex in auditory processing?

A

-generates a map of interaural INTENSITY to localize sound

“L-oudness” … L-ateral

32
Q

What is the role of the inferior colliculus in auditory processing?

A
  • suppresses info related to echo
  • info about time and intensity converge
  • creates precise origin of sound
33
Q

Is the tonotopic map maintained in the inferior colliculus?

A

Yes

34
Q

What is the role of the medial geniculate nucleus (part of the thalamus) in auditory processing?

A
  • distinct spectral and temporal pathways converge
  • process features of speech inflections

-integrates and relays precise info regarding intensity, frequency, and binaural properties of sound

35
Q

Is the tonotopic map maintained in the medial geniculate nucleus?

A

Yes

36
Q

What is the role of the primary auditory cortex (A1) in auditory processing?

A
  • essential in conscious perception of sound

- higher order processing of sound

37
Q

Is tonotopic map maintained in the primary auditory cortex?

A

Yes

38
Q

What is the role of the secondary auditory cortex (Broca’s, Wernicke’s, etc.) in auditory processing?

A
  • responds to more complex sounds such as music and speech

- responsible for identifying a sound

39
Q

Is tonotopic map maintained in the multiple areas that comprise the secondary auditory cortex?

A

-less specific tonotopic arrangement

40
Q

Define sensorineural hearing loss.

A

-problem in the inner ear, either w/ hair cells or the cochlear N.

41
Q

What are the two parts of a cochlear implant?

A

-receiver and electrode

42
Q

What is the purpose of the receiver of a cochlear implant?

A

-decodes the sound signal and delivers it to the electrode

43
Q

Where is the electrode part of the cochlear implant?

A
  • inserted into the cochlea through the oval window

- sits in the cochlear duct w/ CN VIII afferents

44
Q

What does the electrode of a cochlear implant mimic?

A
  • basilar membrane tonotopy
  • electrical signals in distinct areas along the electrode will stimulate particular cochlear N. afferents at discrete frequencies
45
Q

What activates the anterior semicircular canals?

A

-rotation in vertical plane forward

46
Q

What activates the posterior semicircular canals?

A

-rotation in vertical plane backwards

47
Q

What activates the horizontal semicircular canals?

A

-rotation in the horizontal plane

48
Q

What activates the utricle?

A

-linear acceleration forward/backwards

49
Q

What activates the saccule?

A

-linear acceleration up and down

Neuroendocrine Part III (7 decks)

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