1b Auditory Systems Flashcards

1
Q

What does a vestibular organ capture?

A

Captures low frequency motion (movements)

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2
Q

What does a hearing organ capture?

A

Captures high frequency motion (sound)

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3
Q

What is meant by the frequency of a sound?

A

The number of cycles of the sound per second, perceived tone

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4
Q

What is the frequency measured in?

A

Hertz

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5
Q

What is the amplitude?

A

the sound pressure - therefore corresponding to loudness

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6
Q

What is the human range of hearing?

A

20-20000 Hz
0-120 decibels

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7
Q

What are the functions of the outer ear?

A

Capture sound and focus it onto the tympanic membrane

Modest amplification of the upper range of speech frequencies by resonance in the canal

To protect the ear from external threats

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8
Q

By how much does the outer ear amplify the sound?

A

10 DB

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9
Q

What is the middle ear?

A

All the structures from the tympanic membrane to the oval window

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10
Q

What is the main function of the middle ear?

A

Mechanical amplification (Provides an additional 20-30DB)

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11
Q

What happens to the tympanic membrane when a sound hits it?

A

It vibrates at the same frequency as the sound wave which just hit it

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12
Q

What are the ossicles?

A

The three smallest bones in the body -

Malleus
Incus
Stapes

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13
Q

What is the inner ear called?

A

Cochlea

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14
Q

What is the function of the cochlea?

A

function is to transduce vibration into nervous impulses

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15
Q

What two things does the cochlea capture?

A

Captures the pitch and intensity of the sound

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16
Q

Where does the stapes connect to the cochlea?

A

The oval window

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17
Q

Where does the sound go from the oval window of the cochlea?

A

Scala Vestibuli

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18
Q

What does the scala vestibuli and the scala tympani contain?

A

Perilymph

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19
Q

What does the scala media contain?

A

Endolymph

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20
Q

What is the perilymph high in?

A

Sodium

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21
Q

What is the endolymph high in?

A

Potassium

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22
Q

Where is the hearing organ or Organ of Corti Located?

A

In the basilar membrane - separates the scala media and the scala tympani

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23
Q

What type of structures are the scala vestibuli and the scala tymphani?

A

Bone structures

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24
Q

What type of structure is the scala media?

A

Membranous Structure

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25
Q

What structure does the Organ of Corti lie in?

A

The basilar Membrane

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26
Q

Which sound frequency moves the base of the basilar membrane?

A

high frequency sounds

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27
Q

Which sound frequency moves the apex of the basilar membrane of the cochlea?

A

Apex - Wide and loose

Moved by lower frequency (Hz) sounds

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28
Q

How is the basilar membrane arranged?

A

Tonotopically

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29
Q

What are the two types of hair cells which the organ of corti contains?

A

Inner hair cells
Outer hair cells

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30
Q

What is the difference in the way the inner and outer hair cells of the organ of corti are arranged?

A

Inner = one line
Outer = three lines

31
Q

What sits above the hair cells in the cochlea?

A

the tectoral membrane

32
Q

What does the tectoral membrane allow?

A

Allows hair deflection, which in turn depolarises the cell

33
Q

Inner hair cells carry which type of signal?

A

Afferent signals

34
Q

Which nerve do the inner hair cells pass information to?

A

Auditory nerve

35
Q

What is the function of the inner hair cells?

A

Transduction of the sound into nerve impulses

36
Q

What do the outer hair cells do?

A

Carry efferents from the auditory nerve

37
Q

What is the function of the Outer Hair cells?

A

Modulate the sensitivity of the response

38
Q

What are the hairs of the hair cells called?

A

Stereocilium

39
Q

What is the longest cilium called?

A

Kinocilium

40
Q

What does deflection of the stereocilium towards the longest cilium cause?

A

Opening of K+ Channels

41
Q

What happens inside the hair cell when the stereocilium are deflected towards the tallest one?

A

K+ Channels open, Causes depolarisation

Opens Ca2+ channels

leads to the release of an excitatory neurotransmitter (Glutamate) and therefore the simulation of the afferent nerve

42
Q

How does louder sounds affect the sterocilium?

A

Louder sounds deflect the kinocilium more

43
Q

What causes the movement of the sterocilium?

A

The sheer force of the tectoral membrane over the top of the sterocilium will move them

44
Q

What happens when the cells are hyper-polarised?

A

K+ channels are closed

45
Q

What happens to the nerves from the spiral ganglion?

A

Via the vesticulo-cochlear nerve, they travel to the ipsilateral cochlear nuclei in the pons

46
Q

Which cranial nuclei come into the pons?

A

5,6,7,8

47
Q

Where is the cochlear nuclei?

A

In the pons

48
Q

Where does the auditory system nerve decussate?

A

In the brain stem - in the pons, at the superior olive level

49
Q

AWhat area of the thalamus is related to hearing?

A

Medial geniculate body

50
Q

Where is the auditory cortex>

A

The temporal lobe

51
Q

After what point are the auditory connections bilateral?

A

After the superior olive level

52
Q

What are the three types of hearing loss?

A

Conductive
Sensorineural
Central

53
Q

What is conductive hearing loss?

A

Problem is located in the outer / middle ear

54
Q

What is sensorineural hearing loss?

A

Damage to the sensory organ (cochlear) or the nerve (auditory nerve)

55
Q

What is central hearing loss?

A

originates in he brain and the brainstem

56
Q

What is the time fram for sudden hearing loss?

A

Minutes to days

57
Q

What is the time frame for progressive hearing loss?

A

Months to years

58
Q

What is cerumen impaction?

A

Wax in the ear

59
Q

What is otisis

A

inflammation of the middle ear- bubbles can be seen through the ear drum, suggesting there is liquid inside

60
Q

What is otosclerosis?

A

When you get breakdown of the middle ear bones

61
Q

What are the causes of sensorineural hearing loss?

A

Inner ear - noise, presbycusis, ototoxicity

Nerve - acoustic neuroma

62
Q

What is presbycusis?

A

Deterioration of the hair cells due to old age

63
Q

What is ototoxicity?

A

Chemotherapy causes inner ear nerve damage

And Antibiotics - Gentomycin = aminoglycosides

64
Q

What is a vestibular schwaanoma?

A

A unilateral tumour which causes damage to the nerve resulting in sensorineural hearing loss

65
Q

What does a tuning fork?

A

two tests assess the presence of gross hearing

66
Q

what are the two tests done with a tuning fork called?

A

Weber test
Rinne test

67
Q

What is the webber test?

A

Tuning fork placed on top of the head - sound should be heard in the middle

68
Q

What is the Rinne test?

A

tuning fork placed behind the ear

69
Q

If Rinne test is louder than webber, what does this suggest?

A

That your problem is an outer ear / conductive problem

70
Q

What pattern on a audiogram would be seen in conductive hearing loss?

A

Difference between Bone and air conduction

71
Q

What pattern on a audiogram would be seen in sensorineural hearing loss?

A

Same conduction between air and bone

72
Q

What are the four treatments of hearing loss?

A

Fix underlying cause
hearing Aids
Cochlear Implants
Brainstem Implants

73
Q

What is Otoacoustic emissions?

A

They are the normal sounds produced by the cochlea

produced specifially by the outer hair cells as they expand and contract

74
Q

What special test is part of the newborn hearing screening and hearing loss monitoring?

A

Otoacoustic Emissions