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Module 202 Neuroscience & behaviour > T2 L12 Physiology of hearing > Flashcards

T2 L12 Physiology of hearing Flashcards

1
Q

What are the functions of hearing?

A

Altering to dangers
Localisation of objects
Recognition
Communication via speech

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2
Q

What are sounds?

A

Pressure waves that propagate through air at 340m/s

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3
Q

What is the equation for intensity?

A

dB = 10 x log (sound intensity / reference intensity) or 20 x log (sound pressure / reference pressure)

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4
Q

What is the range of frequencies of ideal human hearing?

A

20-20,000Hz

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5
Q

Above what intensity can lead to permanent hearing damage?

A

90dB

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6
Q

What forms the peripheral auditory system?

A

Outer ear
Middle ear
Cochlea
Auditory nerve

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7
Q

What is the function of the middle ear?

A

Transmit sound from outer to inner ear.

Transmits vibrations from tympani to oval window of cochlea & increases pressure by 45X

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8
Q

What is Ottis media?

A

Known as glue ear

Infection or inflammation of middle ear

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9
Q

What can Ottis media be caused by?

A

Upper respiratory tract infection

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10
Q

What happens if glue ear is chronic?

A

It can lead to conductive hearing loss

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11
Q

What is the treatment for glue ear?

A

Grommets to drain

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12
Q

What is otoscleorsis?

A

Fusion of the stapes with the oval window

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13
Q

What is the cochlea?

A

Long, coiled, fluid-filled tube

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14
Q

What sounds does the basal end of the cochlea detect?

A

High frequency sounds

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15
Q

What sounds does the apical end of the cochlea detect?

A

Low frequency sounds

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16
Q

How do scala vestibule and scala tympani communicate?

A

Via helicotrema at apex of cochlear

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17
Q

What areas contain perilymph?

A

Scala vestibular

Scala tympani

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18
Q

What is the composition of perilymph?

A

High Na+

Low K+

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19
Q

What areas contain endolymph?

A

Scala media

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20
Q

What is the composition of endolymph?

A

High K+

Low Na+

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21
Q

What is the function of the organ or corti?

A

Detect sound-induced motions of basilar membrane and convert them into electrical signals

22
Q

What are the 2 types of sensory hair cells?

A

Inner hair cells

Outer hair cells

23
Q

What are the inner hair cells innervated by?

A

Afferent nerve fibres

24
Q

What are the outer hair cells innervated by?

A

Efferent nerve fibres

25
Q

What membrane of the hair cells is bathed in endolymph?

A

Apical membrane

26
Q

What membrane of the hair cells is bathed in perilymph?

A

Basolateral membrane

27
Q

How many hair cells in each human cochlea?

A

15,000

Don’t regenerate

28
Q

Describe mechanotransduction in hair cells

A

Deflection of hair bundle –> opens nonselective cation channels
K+ is the major cation in endolymph so it enters & depolarises hair cells. Ca2+ enters & causes adaption
Ca2+ triggers release of vesicles

29
Q

What is the movement of K+ in endolymph driven by?

A

Electro-gradient

30
Q

What do outer hair cells do to the basilar membrane motion?

A

Amplify it

31
Q

What is Prestin?

A

Modified anion exchanger in basolateral membrane

Outer hair cell motor

32
Q

What type of axons innervate an inner hair cell?

A

10-20 type I spiral neurons

33
Q

What is the function of type I spiral neurons?

A

Signal reception of sound over a wide range of intensities to the brain

34
Q

What type of axons innervate outer hair cell?

A

Type II spiral neurons

35
Q

What is the function of type II spiral neurons?

A

Signal reception of painfully loud sound that causes cochlear damage to the brain

36
Q

What do efferent fibres from medial olive innervate?

A

Outer hair cells

37
Q

What do efferent fibres from lateral olive synapse on?

A

Type I afferent fibres

38
Q

What can cause sensorineural hearing loss?

A

Noise
Ageing
Oxotoxic drugs
Genetic mutations

39
Q

How can noise cause sensorineural hearing loss?

A

Physical effects on hair bundle structure
Mitochondrial damage, cytotoxic free radicals
Glutamate excitotoxicity

40
Q

How can ageing cause sensorineural hearing loss?

A

Hair cells
Stria vascularis
Cochlear ganglion

41
Q

What drugs are ototoxic?

A 
Aminoglycoside antibiotics
Cisplatin
Loop diuretics
Salicylate
Solvents
42
Q

What are some targets of deafness genes in the cochlea?

A 
Tight junctions
Gap junctions
Afferent synapse
Tectorial membrane
Stria vascularis
Transduction complex
43
Q

What are cochlear implants?

A 
Surgically implanted electronic device that provides sound to person who is profoundly deaf
Expensive
Maximum of 24 channels
Speech sounds robotic
music sounds awful
44
Q

Where does parallel processing start?

A

In cochlear nucleus

45
Q

What is the superior olivary complex?

A

2 binaural cues to localise sound in space

46
Q

Where are interaural intensity differences detected?

A

In lateral superior olive

47
Q

Where are interaural time differences detected?

A

Medial superior olive

48
Q

What is the inferior colliculus?

A

Obligatory synaptic station for all afferents
Laminar organisation, iso-frequency sheets
Combines complex frequency & amplitude analysis of DCN with information on sound localisation from SOC
Encode complexity & localisation of sounds
Auditory reflex centre, reflexive orientation to stimuli

49
Q

Where is the primary auditory cortex located?

A

Upper surface of temporal lobe

50
Q

What do lesions in auditory cortex cause?

A

Defects in sound localisation
Discrimination of temporal pattern
Intelligibility of speech

51
Q

What do lesions in Broca’s & Wernicke’s area cause?

A

Impair production & comprehension of speech

Module 202 Neuroscience & behaviour (39 decks)

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