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NPB 110B Midterm #3 (Final) > Auditory System I > Flashcards

Auditory System I Flashcards

1
Q

What are the three main subdivisions of the human ear?

A

The outer ear

the middle ear

the inner ear

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2
Q

What are the two functions of the outer ear?

A

Collection

Collect sounds

The shape of the pinna called in the localization of sound

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3
Q

What is is the function of the middle ear?

A

Amplification

Solves the “impedance mismatch” problem between the air (from the outer ear) and the fluid-filled spaces of the inner ears

Efficiently transfer acoustic energy from compression waves in air to fluid

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4
Q

True or False: Liquid is much less compressible so when soundwaves hit an air/liquid interface they become very much attenuated

A

Amplification (Middle ear)

True

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5
Q

Three bones of the middle ear take the vibration of the large _______________ and compress it into the small area of the ___________ allowing a relatively large wave to be set up in the fluid-filled inner ear.

A

Tympanic membrane

Oval window

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6
Q

Where can you find the sensory receptors of the auditory system and where sensory transduction occurs?

A

In the inner ear

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7
Q

Which ear is much simpler than the mammalian ear? Why?

A

Amphibian ear

  • no external ear
  • no middle ear –> because there is no impedance mismatch between the water they live in and the fluid-filled inner ear
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8
Q

True or False: Fish have specialized structures for hearing.

A

False: they have no specialized structures for hearing

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9
Q

Let’s look at the inner ear

What are the type of cells that transfer sound waves into a neuronal signal?

A

Hair cells

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10
Q

Where are hair cells located?

A

Located in the organ of Corti

that sits in the scala media on the basilar membrane

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11
Q

What are stereocilia?

A

They are mechanoreceptors that respond to the movement of their hairs.

They sit on top of the hair cells

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12
Q

When stereocilia are moved towards the shortest sterociliuluim the cell (depolarized/ hyperpolarizes)

When stereocilia are moved towards the tallest sterociliuluim the cell (depolarized/ hyperpolarizes)

A

Hyperpolarizes

Depolarized

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13
Q

What causes the change in membrane potential of hair cells, when the stereocilia move?

A

Non-specific cation channels located in the tips of the stereocilia

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14
Q

What are the protein that is on the tip of the stereocilia?

A

Tip Links –> Spring Link Proteins direct connected from tip of one stereocilium to the cation channel in the tip of neighboring stereocilia.

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15
Q

When the stereocilia moves toward the taller stereocilia, the tip links physically pull up on the channels causing them to (open/close) more.

A

Open

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16
Q

When the stereocilia move towards the shorter stereocilia, the tip links relax and the channels (open/close).

A

Close

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17
Q

What cation enter the hair cells that cause depolarization?

A

K+

due to very high concentration of K+ in the endolymph

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18
Q

What does this potential change do to V.G. Ca2+ channels in the basal portion of the cell membrane of the hair cell?

A

Open the channels

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19
Q

What do the influx of K+ and Ca2+ ions in the hair cell do to transmitter releases from hair cells?

A

Increase release ; Increase action potential firing in the 8th cranial nerve

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20
Q

True or False: Hair cells want to simplify the signal and one way to do is by adaptation.

A

True

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21
Q

Mechanisms of adaptation in the hair cells in the movement of tip links. They are attached by a ________ to actin filaments in the stereocilia.

A

Myosin Motor

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22
Q

True or False: The motor is constantly running up the actin filament to keep the tip links tight, such that at rest (when the stereocilia is not bent) about 15% of each cation channels are open.

A

True

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23
Q

When ____ enter the cell, as well as causing transmitter releases, it causes the myosin to slip (up/down) the actin filament, (strengthening/loosening) the tip links.

A

Ca2+

down

loosening

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24
Q

The myosin motor slipping down and the loosening of the tip links mean that the same movement of the stereocilia will open the channels and (more/less) transmitter is released –adapted.

A

Less

25
Q

Encoding frequency

Hair cells at (different/similar) places along the _________ in the cochlea response to (similar/different) frequencies (pitches) of sound.

A

Different

Basilar membrane

different

26
Q

What can you use to plot the different response of hair cells to different frequencies of sound?

A

Auditory tuning curves

27
Q

True or False: Tuning curves are plotted showing the cell response level given by the frequency of the sound stimulus. (Auditory System)

A

False

Rather plots the threshold of sound intensity at which the cell responds to a given frequency of the sound stimulus.

28
Q

What is “best frequency” or “characteristic frequency”?

A

The frequency to which an auditory cell at the lowest intensity response to the most.

29
Q

What is the main cause of the frequency tuning of hair cells in mammals?

A

Different parts of the basilar membrane vibrate in response to different frequencies of sound.

30
Q

What do the first two graphs respond in the basilar membrane?

A

Apical

31
Q

The (apical/basal) end of the basilar membrane is thick and narrow, response to higher-frequency sounds.

A

Basal

32
Q

The ____ the membrane moves, the more the hair cell stereocilia bend, and so the more hair cells _________.

Therefore the hair cells at the _______ end of the membrane depolarize in response to high frequencies sound while those at the ______ end depolarize in response to low-frequency sounds.

A

More

Depolarize

basal

apical

33
Q

Which species’ hair cells can generate oscillating membrane potentials?

A

Lower vertebrates

34
Q

What happens when the Ca2+ gated K+ channels open?

Recall, that there at the bottom of the hair cells in the perilymph region. (low [K+])

A

K+ moves out –> hair cells are hyperpolarized

35
Q

When the Ca2+ gated K+ inactivate quickly, what happens when they close?

A

The cell is depolarized again if the sound is still present.

36
Q

What is electrical tuning frequency?

A

The frequency at which the membrane potential oscillates when a hair cell is depolarized.

37
Q

The frequency of the electrical oscillation matches the best frequency of the hair cells, so it ______ the response of the hair cells.

A

Amplifies

38
Q

Outer hair cells (contracts/extends) when they are polarized.

A

Contract

39
Q

Outer hair cells (extend/contracts) when they are hyperpolarized.

A

Extends

40
Q

The contraction of the outer hair cells moves the basilar membrane ________ at their hair cells best frequency, ______ the motion of the membrane in response to that frequency of sound.

A

up and down

magnifying

41
Q

Central auditory pathways

Information leaves the _______

Enter the brain via __________

________ synapse in several brainstem neclyi which send projection to the __________.

The _____ then sends connections to the auditory cortex.

A

Cochlea

8th cranial nerve

8th nerve fibers

thalamus

MGN

42
Q

What information is encoded in the auditory system, as in all sensory systems?

A

Stimulus modality

Intensity

Duration

Location

43
Q

Hair cells and CNS auditory neurons encode _______ differently.

A

Intensity

44
Q

Hair cells are _________ to different intesnities of sound

A

graded response

45
Q

CNS auditory neruons fire _____.

A

A.P

46
Q

Since all of the responses oscillate at the frequency of sound stimulus –> A.P are fired in ________ and the frequency of the burst is related to the frequency of the ____________.

A

burst

sound stimulus

47
Q

True or False: The firing rate can be used to signal stimulus intensity.

A

False

Firing-rate cannot be used to signal stimulus intensity.

48
Q

Instead the auditory system encoded intensity by the __________________.

A

of neurons that are firing in response to a given stimulus.

49
Q

True or False: Duration encoded by how long the hair cells membrane potential is oscillating or how long the auditory neuron is firing

A

True

50
Q

What is tonotopy in the auditory system?

A

Different locations on cochlea

51
Q

What do different location on the cochlea correspond to?

A

Different sound frequencies

52
Q

What do profoundly deaf patients lack? What are you still functioning?

A

Lack hair cells but have functioning 8th cranical nerves

53
Q

Cochlear implants work by having ___________ along the basilar membrane and stimulate the nerves at ___________.

A

20 stimulating electrodes

20 different locations

54
Q

The input of the 20 stimulating electrodes are not as precise a input of a normal human ear ___________, but it allows most patients to understand normal conversations.

A

16,000 hair cells

55
Q

True or False: The auditory cortex is similar to somatotopic in the somatosensory cortex and the visual cortex.

A

True

56
Q

In order to increase the decibel, threshold, measurement of a sound, one would have to alter its wave ___________

A

amplitude

57
Q

What feature of the cochlear prevents it from rupturing when the fluid column is set in motion?

A

The pressure is relieved by pushing out the round window at the other end of the cochlea.

58
Q

What effect does fluid movement in the cochlear have on the basilar membrane?

A

It creates a traveling wave that moves along the basilar membrane

59
Q

In the figure below, if neuron 3 fires in this array, which direction did the sound come from?

A

The sound came from straight ahead

NPB 110B Midterm #3 (Final) (9 decks)

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