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NE Exam 3 > 2 - Physiology of Auditory & Vestibular System > Flashcards

2 - Physiology of Auditory & Vestibular System Flashcards

1
Q

The basilar membrane varies in structure over its length with the membrane being _______ and _______ near the oval and round windows, but ________ and _______ near the helicotrema.

A

Narrow
Stiff
Wide
Flexible

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2
Q

(LOW/HIGH) frequency sounds cause greater deflection of the basilar membrane where it is narrow and stiff, and (LOW/HIGH) frequency sounds produce greater deflection where the basilar membrane is loose and flexible.

A

High

Low

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3
Q

The frequency of sound, called ________, is coded by where along the basilar membrane there is the greatest deflection.

A

Pitch

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4
Q

This is what detects sound and uses acoustic cues to identify and locate sound sources in the environment.

A

Auditory System

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5
Q

This is the term for oscillations of air pressure that vary rapidly with time.

A

Sound

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6
Q

This is the term for the sound pressure (intensity) specified by a scale of sound pressure level (SPL) in decibels (dB).

A

Amplitude

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7
Q

This is the term for the number of oscillations of air pressure per second (Hz).

A

Frequency

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8
Q

T/F. When the basilar membrane is narrow and stiff, it allows it to vibrate more causing a higher frequency and high-pitched sound. When the basilar membrane is wide and flexible, it isn’t able to vibrate as much and causes a lower frequency and low-pitched sound.

A

True

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9
Q

The (BASE/APEX) of the basilar membrane is narrow and stiff and is where the propagation of each sound wave begins. High-frequency sounds produce their maximal displacement at the base. The (BASE/APEX) of the basilar membrane, on the other hand, is wider and more flexible and is where low-fequency sounds are perceived.

A

Base

Apex

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10
Q

The mechanical properties of the basilar membrane results in the _________ of the inner ear, with distinct locations interpreting discrete frequencies. This is analogous to the somatotopy of the sensory systems, and is carried forward throughout the auditory pathway.

A

Tonotopy

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11
Q

Due to the fact that the cochlea is a closed-structure with one point of entrance and another point of exit for the dissipation of energy, the vibration of the basilar membrane creates a _________ differential.

A

Pressure

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12
Q

The pressure differential created by the vibration of the basilar membrane results in a shearing force against the stationary ________ ________. This causes the ________ of the outer hair cells to be displaced in that plane.

A

Tectorial Membrane

Stereocilia

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13
Q

The (OUTER/INNER) hair cells are not in direct contact with the tectorial membrane and are activated through fluid movement in the cochlear duct.

A

Inner

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14
Q

Depolarization of the cell occurs when cation channels open at the apex of the stereocilia. Stereocilia are connected to each other via _____ _____ that transit force to an elastic gating spring which, in turn, opens the _______ channels.

A

Tip Links

TRPA1

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15
Q

TRPA1 channels are examples of ___________ channels, which have the advantage of conferring immediate effects. In fact, hair cells can respond to stimulus within 50 microseconds. Such a rapid response would not be possible with a slow chemical signal transduction process.

A

Mechanotransduction

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16
Q

Another advantage of mechanotransduction channels is that they do not require receptor potentials, thereby increasing the _________ of the response. Even small vibrations of 0.3 nm (the size of an atom) can cause channel opening.

A

Sensitivity

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17
Q

This is the potassium-rich fluid filling the cochlear duct and the membranous labyrinth. It bathes the apical end of the hair cells.

A

Endolymph

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18
Q

Endolymph is similar to intracellular fluid (ICF) in that it is high in ________ and low in ________.

A

Potassium

Sodium

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19
Q

Endolymph is found in the _______ _______ and produced by the ________ ________.

A

Scala Media

Stria Vascularis

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20
Q

This is the potassium-poor fluid that bathes the basal end of the cochlear hair cells.

A

Perilymph

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21
Q

Perilymph is similar to extracellular fluid (ECF) in that it is high in ________ and low in ________.

A

Sodium

Potassium

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22
Q

Perilymph is found in the…

A

Scala Vestibuli

Scala Tympani

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23
Q

Ion channels called TRPA1 channels on stereocilia tips are opened when the Tip Links joining the stereocilia are stretched. Because the stereocilia are bathed in the endolymph of the cochlear duct, the opening of the TRPA1 channels will cause a rapid influx of _______ into the cell.

A

Potassium

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24
Q

The rapid influx of potassium into the hair cells causes it to depolarize, which causes ________ channels at the base of the cells to open.

A

Calcium

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25
Q

Calcium influx at the base of hair cells causes neurotransmitter-filled vesicles to fuse with the basilar membrane and release the neurotransmitter ________ into the synaptic cleft. The afferent cochlear nerve fibers are thus stimulated (spiral ganglion neurite) and transmit this signal to the CNS.

A

Glutamate

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26
Q

The tips of the stereocilia on the hair cells are embedded in the _______ _______, and the bodies of hair cells rest on the _______ _______.

A

Tectorial Membrane

Basilar Membrane

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27
Q

An upward displacement of the basilar membrane creates a shearing force that results in lateral displacement of the stereocilia. Mechanical displacement of the stereocilia in a lateral direction causes (DEPOLARIZATION/HYPERPOLARIZATION) of the hair cell.

A

Depolarization

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28
Q

A downward displacement of the basilar membrane creates a shearing force that results in (DEPOLARIZATION/HYPERPOLARIZATION) of the hair cell.

A

Hyperpolarization

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29
Q

The inner hair cells are responsible for ________. About 90 percent of cochlear nerve fibers come from the inner hair cells.

A

Hearing

30
Q

The outer hair cells ________ the signals that are then processed by the inner hair cells.

A

Amplify

31
Q

The Stria Vascularis, located in the lateral wall of the cochlear duct (Scala Media), produces the endolymph with high levels of K+ that fills the entire ________ _______.

A

Membranous Labyrinth

32
Q

Stratified epithelial cells of the Stria Vascularis extend cytoplasmic processes and folds around the capillaries of an unusual intraepithelial plexus. ________ released from the capillaries is transported across tightly joined cells at the strial surface into the endolymph, which bathes the stereocilia of the hair cells and produces conditions optimal for depolarization.

A

Potassium

33
Q

This is what maintains the electrochemical properties of the endolymph.

A

Stria vascularis

34
Q

The high endocochlear potential, _____ mV, serves to drive positively charged ions into the hair cell down their concentration gradient. This endocochlear potential is maintained by the Stria Vascularis, and forms what is known as the ________ ________ _________.

A

+80

Blood-Labyrinth Barrier (BLB)

35
Q

The BLB is one of the main sites of drug entry to access the inner hair cell, sometimes to its detriment. Any substance such as ototoxic drugs, carbon monoxide, etc. that disrupts the function of the _______ _______ will diminish the endocochlear potential and thus impact hearing.

A

Stria Vascularis

36
Q

These are the primary source of auditory information. They are arranged in a single layer and synapse with the peripheral terminal of a primary afferent sensory neuron. An efferent neuron also modulates activity as well.

A

Inner hair cells

37
Q

These are the primary cells that amplify sound waves that results in the movement of the basilar membrane. These cells are also contractile, which makes them a specialized type of epithelial cell.

A

Outer hair cells

38
Q

Outer hair cells contractile properties boosts the mechanical vibrations of the basilar membrane, which makes them act like an _________.

A

Amplifier

39
Q

There are ________ rows of outer hair cells compared to the single row of inner hair cells.

A

Three

40
Q

Outer hair cells also form a synapse with sensory afferent peripheral terminals from the _______ _______, as well as with terminals from efferent neurons.

A

Spiral Ganglion

41
Q

Another interesting feature of auditory physiology is known as ________ ________. Because the motility of the outer hair cells can cause the basilar membrane to move, it is conceivable that this movement could be retrograde, or backward, toward the oval window and through the middle ear via the ossicles to cause displacement of the _______ _______.

A 
Otoacoustic Emissions (OAE) 
Tympanic Membrane
42
Q

In OAE, the ear itself is producing a sound. These sounds can be measured in the…

A

External Auditory Meatus

***These measurements are routinely done in infants to assess the function of the inner and middle ears.

43
Q

The Medial Olivary Complex neurons innervate _______ hair cells.

A

Outer

44
Q

The Lateral Olivary Complex neurons innervate _______ hair cells.

A

Inner

45
Q

Neurons for OAE originate in the _______ _______ _______ and are known as _________ efferents.

A

Superior Olivary Complex

Olivocochlear

46
Q

OAE testing measures the presence of absence of sound waves generated by the cochlear outer hair cells in response to sound stimuli. A microphone at the external ear canal detects the low-intensity OAEs. Since OAE evaluates hearing from the middle ear to the outer hair cells, it is used to screen for __________ hearing loss but cannot detect auditory neuropathy.

A

Sensorineural

47
Q

These reduce electromotility of hair cells, decreases basilar membrane motion, and reduces the responses of inner hair cells and auditory nerve fibers.

A

Olivocochlear efferents

48
Q

Medial ear efferents innervate the _______ _______ to the malleus and the tympanic membrane, and the _________ to the stapes (from CN VII). Both of these are responsible for attenuating (reducing force of) sound.

A

Tensor tympani

Stapedius

49
Q

These efferents arise from CN VIII and give sympathetic adrenergic fibers. They regulate vascular tone in blood supply to cochlea.

A

Autonomic efferents

50
Q

These efferents have bilateral response to high sound levels and work to prevent damage and protect hair cells from damage to intense sounds.

A

Medial ear efferents

51
Q

This nuclei integrates the acoustic information with somatosensory information.

A

Dorsal (posterior) cochlear nuclei

52
Q

This nuclei begins processing the temporal and spectral features of the sound.

A

Ventral (anterior) cochlear nuclei

53
Q

This receives glutamatergic (excitatory) input and generates a map of interaural TIME differences to help localization of sound.

A

Medial Superior Olivary Complex (MSO)

54
Q

This receives glutamatergic (excitatory) input and generates a map of intramural INTENSITY differences to help localize the source of a sound.

A

Lateral Superior Olivary Complex (LSO)

55
Q

This suppresses information related to echoes, which would interfere with localization and arrives at a final estimation of localization of sound along the horizon.

A

Inferior Colliculus (IC)

56
Q

Information about time and intensity (from MSO and LSO) converge into the _______ _______ to help create a precise origin of sound location along the horizon.

A

Inferior Colliculus (IC)

57
Q

This is part of the thalamus and has lots of convergence from distinct spectral and temporal pathways, allowing for processing features of speech inflections. Precise information regarding intensity, frequency, and binaural properties of sound are integrated and relayed onward.

A

Medial Geniculate Nucleus (MGN)

58
Q

This is essential in conscious perception of sound. Higher order processing of sound (loudness, modulations in volume, rate of frequency modulation).

A

Primary Auditory Cortex (A1)

59
Q

This is composed of multiple areas (Broca’s, Wernicke’s, etc.) and is less specifically organized in the tonotopic arrangement than the primary auditory cortex. This is though to respond to more complex sounds (music), identifying (naming) a sound, and speech.

A

Secondary Auditory Association Cortex (A2)

60
Q

This type of hearing loss results from a problem in the inner ear, either with the hair cells or with the cochlear nerve itself. Hair cells are very susceptible to damage and do not regenerate in humans.

A

Sensorineural

61
Q

A cochlear implant consists of an external and an internal component. The internal component includes a ________ and an ________ ________. The ________ decodes the signal and delivers the electrical signals to the _______ ________.

A

Receiver
Electrode array
Receiver
Electrode array

62
Q

In a cochlear implant, the electrode array is inserted into the cochlea through the _______ _______ where it sits in the cochlear duct along the afferents from CN VIII. Electrical signals anywhere along the electrode array will stimulate a particular cochlear nerve afferent along the basilar membrane. The electrode array mimics the tonotopy of the basilar membrane and stimulates nerves at discrete frequencies.

A

Oval window

63
Q

This is responsible for forward rotation in the vertical plane.

A

Anterior semicircular canal

64
Q

This is responsible for rotation in the horizontal plane.

A

Horizontal semicircular canal

65
Q

This is responsible for backward rotation in the vertical plane.

A

Posterior semicircular canal

66
Q

This detects linear acceleration forward and back.

A

Utricle

67
Q

This detects linear acceleration up and down.

A

Saccule

68
Q

Describe the process of what happens when soundwaves come into the ear.

A

Soundwaves hits Stapes and causes it to move —

Scala vestibuli pressure falls below Scala Tympani pressure —

This causes Basilar membrane to bow upward —

Organ of Corti shears toward hinge of Tectorial membrane, causing hair bundles of outer hair cells to tilt toward Kinocilium —

Transduction channels open in outer hair cells and cause depolarization —

This causes contractile proteins to accentuate upward movement of Basilar membrane, which makes waves in endolymph —

Endolymph waves move beneath tectorial membrane and cause inner hair cells stereocilia to tilt toward their Kinocilium —

Transduction channels open in inner hair cells and cause depolarization, which opens voltage-gated calcium channels —

The calcium causes synaptic vesicles to fuse, releasing glutamate (or ACh) —

This signal cascade sends the sound info to the brain, inner hair cells are the primary source of auditory information to the brain.

69
Q

Hair cells receive afferent innervation from the _______ _______ and efferent innervation from the _______ _______ _______.

A

Spiral Ganglia

Superior Olivary Complex

70
Q

This is the first site in the brainstem where information from both ears converges. This binaural processing is essential to accurately localize sound. It receives glutamate (excitatory) input.

A

Superior Olivary Complex

***Remember, Medial (MSO) = time, and Lateral (LSO) = intensity

71
Q

This is what takes the location data from the Inferior Colliculus and adds the final dimension (vertical height) to create a spatial map of the sound’s location.

A

Superior Colliculus

72
Q

This is in the thalamus and is a relay station in the auditory pathway. It provides lots of convergence from distinct spectral and temporal pathways, allowing for processing features of speech inflections.

A

Medial Geniculate Nucleus (MGN)

NE Exam 3 (16 decks)

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