Auditory System Flashcards

1
Q

What bone is the ear found in?

A

The petrous portion of the temporal bone

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2
Q

What is the function of the outer ear?

A

Capture sound and focus it on the tympanic membrane
Amplify some frequencies via resonance in the canal
Protect the ear from external threats

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3
Q

What is the function of the middle ear?

A

Focusing vibrations from large surface area to smaller surface area (this increases pressure)

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4
Q

What is the function of the inner ear? What structure performs these functions?

A

The cochlea:
Transduces vibration into nervous impulses
Analyses frequencyand intensityof the sound

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5
Q

What are the 3 parts of the cochlea?

A

Scala vestibuli
Scala tympani
Scala media

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6
Q

What in the cochlea contains perilymph? What are the characteristics of perilymph?

A

Scala vestibuli and typmani, perilymph is high in sodium

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7
Q

What in the cochlea contains endolymph? What are the characteristics of endolymph?

A

Scala media, endolymph is high in potassium

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8
Q

Where is the organ of corti located?

A

In the scala media in the cochlea

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9
Q

What is the basilar membrane?

A

Where the organ of corti lies

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10
Q

How is the basilar membrane arranged? What does this mean

A

Arranged tonotopically

It is sensitive to different frequencies at different points along its length

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11
Q

What 2 types of hair cells are found in the organ of corti? How are they arranged?

A

Inner hair cells arranged in one column

Outer hair cells arranged in 3 columns

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12
Q

How are hairs in the organ of corti deflected?

A

The tectorial membrane lies above them and allows deflection which then depolarises the cell

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13
Q

What information do the inner hair cells carry and what is their function?

A

Afferent info

Their function is the transduction of the sound into nerve impulses

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14
Q

What information do the outer hair cells carry and what is their function?

A

Efferent info

Their function is modulation of the sensitivity of the response.

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15
Q

What hairs of hair cells in the ear called?

A

Stereocilia

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16
Q

Describe how transduction of sound occours in relation to hair cells?

A

Stereocilia deflect towards the longest cilium, opening K+ channels
Inflow of K+ depolarises the cell and neurotransmitter is released
Louder sounds causes greater deflection

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17
Q

Describe the auditory pathway

A

Spiral ganglions from the cochlea project to the ipsilateral cochlear nuclei, the info crosses at the superior olive level then all connections are bilateral

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18
Q

What is the human range of hearing for frequency?

A

20–20,000Hz

19
Q

What is the human range of hearing for loudness?

A

0 dB to 120 dB

20
Q

What are the main assessments for hearing?

A

Audiometry
Tuning fork
Central processing assessments

21
Q

When are tuning forks used as an assessment for hearing?

A

To establish absence or presence of hearing when audiometry isn’t available

22
Q

What is pure tone audiometry?

A

Measuring hearing acuity for variations in sound intensity and frequency performed using an audiometer

23
Q

What is a central processing assessment?

A

Assessment of hearing abilities other than detection

24
Q

What is tympanometry?

A

Examination used to test the condition of the middle ear and mobility of the eardrum (tympanic membrane) and the conduction bones

25
Q

What are otoacoustic emissions (OEAs)?

A

The low intensity sounds a cochlea produces

26
Q

How are OEAs used in newborns?

A

They are assessed in newborns to screen their hearing ability or measure progression of hearing loss

27
Q

What type of electrical activity does electrocochleography measure?

A

From the cochlear and vestibulocochlear nerve

28
Q

What type of electrical activity does auditory brainstem response measure?

A

From the vestibulocochlear nerve and brainstem nuclei/tracts

29
Q

What type of electrical activity do late responses measure?

A

From the primary auditory and association cortex

30
Q

What are the 3 types of hearing loss?

A

Conductive
Sensorineural
Mixed

31
Q

Where is the problem located in conductive hearing loss?

A

Outer or middle ear

32
Q

Where is the problem located in sensorineural hearing loss?

A

Inner ear or auditory nerve

33
Q

Where is the problem located in mixed hearing loss?

A

Affects more than one part

34
Q

What about sound is effected in mixed hearing loss?

A

Conduction and transduction

35
Q

How can hearing loss be classified?

A

Mild, moderate, severe or profound

36
Q

What are some causes of conductive hearing loss?

A

Wax or foreign body
Otitis (bubbles in eardrum)
Otosclerosis

37
Q

What are some causes of sensorineural hearing loss?

A

Presbycusis
Ototoxicity
Nerve VIII tumor

38
Q

What are the 3 main treatments for hearing loss?

A

Hearing aids
Cochlear implants
Brainstem implants

39
Q

What do hearing aids do?

A

Amplify sound but do not replace any structure

40
Q

What do cochlear implants do?

A

Replaces the function of the hair cells by receiving sound, analysing it, transform it into electrical signals and sending an electric impulse directly to the auditory nerve

41
Q

What do cochlear implants need to work?

A

A functioning auditory nerve

42
Q

What do brainstem implants do?

A

The electrical signals can be sent to a set of electrodes placed directly into the brainstem

43
Q

When are brainstem implants used?

A

When auditory nerves are affected

44
Q

How risky are brainstem implants?

A

Very risky, should only be used if people have bitemporal auditory nerve damage