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LCRS - neuro > auditory system - obsolete > Flashcards

auditory system - obsolete Flashcards

1
Q

What is the human hearing range?

A

20Hz - 20kHz

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2
Q

define pitch

A

perception of frequency

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3
Q

how is sound intensity defined?

A

amount of energy delivered per second - number of Joules per second passing through one square meter.

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4
Q

How is sound measured.

A

Decibel scale - logarithmic comparison of intensity as opposed to linear.

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5
Q

What is the sensory receptor of the internal ear?

A

hair cells.

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6
Q

What is a hair bundle?

A

cluster of modified microvilli called stereocilia

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7
Q

Define impedance.

A

the reluctance of a system in receiving energy from a source.

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8
Q

What is the frequency at which impedance of the system is minimal called?

A

resonant frequency.

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9
Q

What is the role of the ossicles?

A

match the impedance and reduce the loss in energy as the vibration goes from the air to the cochlea

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10
Q

What is conductive hearing loss?

A

when the ear is not capable of transmitting the vibration of sound waves onto the cochlea

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11
Q

What can cause conductive hearing loss?

A

fluid accumulation in children. perforated tympanic membrane. abnormal growth of bone obstructing ear canal. barotrauma.

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12
Q

Diabgram of ear including cochlea.

A
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13
Q

What is contained within the organ of corti?

A

basilar + tectorial membranes.

Hair cells.

Supporting cells.

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14
Q

How does the cochlea relay information to the basilar membrane?

A

Motion of stapes generates difference in pressure between the two liquid-filled chambers of the cochlea –> vibration of basilar membrane

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15
Q

What is the role of the basilar membrane?

A

frequency analyser.

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16
Q

How does the basillar membrane process vibrations?

A

elastic structure with heterogenous mechanical properties - vibrates at different positions along its length according to different frequencies.

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17
Q

What is the role of the basilar membrane?

A

breaks complex sounds down

18
Q

How is information from the basilar membrane receives?

A

sensory recptors along its length detect the frequences of vibration - hair cells.

19
Q

How do hair cells relay information to the brain?

A

motion of basilar membrane deflects the sterocilia.

This bending towards the tallest stereocilium changes internal cell voltage, producing an electric dignal towards the brain.

mechano-transduction (MT)

20
Q

What is the role of tip links?

A

tip links connect sterocilia.

Their stretching as sterocilia bend opens ion channels which generate repsonse currents.

ion channel opening relaxes the tip link, relaxing the hair bundle.

21
Q

Is hair bundle movement an active or passive process?

A

active due to capacity to do work.

22
Q

Compare the sparsity of Inner and outer hair cells.

How do their roles differ?

A

IHCs - 3500 per human cochlea

OHCs - 110000 per human cochlea.

IHCs - afferent projections (to brain) - relay info.

OHCs - efferent projections (from brain to ear) - cochlear amplification.

23
Q

How do OHCs aid cochlear amplification?

A

They stretch and elongate when internal voltage changed - electromotility.

Due to reorientation of prestin.

24
Q

How is frequency specific information relayed from the hair cells to the cochlear nucleus?

A

hair cells synapse to the sensory neurons in the cochlear ganglion (spiral ganglion). Each ganglionc cells responds to stimulation at a particular frequency.

25
Q

What is the pathology of senorineural hearing loss?

A

damage to sensory apparatus of Inner ear or to the vestibularcochlear nerve.

26
Q

What can cause sensorineural hearing loss?

A

Loud noises

genetic mutations affecting Organ of Corti

aminoglycoside antibiotics = hair cell toxic

congenital diseases

acoustic neuroma

ageing.

27
Q

How can cochlear implants compensate for hearing loss?

A

bypass dead hair cells and stimulate nerve fibres directly.

28
Q

What is the role of the cochlear nucleus?

A

arrange neurons tonotopically (low frequencies = ventral)

29
Q

What is the role of the doral cochlear nucleus?

A

processing high frequency sounds that produce interference wit the body due to the size of the sound wave.

30
Q

What is the role of the superior olivary complex?

A

compare bilateral activity of cochlear nuclei

31
Q

What is the role of the medial superior olive?

A

calculation of interaural time difference

32
Q

What is the role of the lateral superior olive?

A

detect difference in intensity between two ears.

Interaural level difference compused to localise sounds in the horizontal plane.

33
Q

How does the lateral superior olive detect differences in intensity between hears?

A

Comparing inhibitory and excitatory information from the contralateral and ipsilatreral sides respectively (how long they take)

34
Q

How does the SOC protect against damage by loud sounds?

A

SOC sends feedback to hair cells - increased representation of signals in noise protects against damage.

35
Q

How can sensorineural hearing loss occur (malfunctioning of auditory pathway to brain)

A

demyelination.

blast injuries upset excitation/inhibition balance.

36
Q

What is the role of the inferior colloculus?

A

convergence of ascending auditory pathways.

Signal integration - precedence effect.

37
Q

What is the role of the superior colliculus?

A

auditory and visual maps merge. Neurons are tuned to respond tostimuli with specific sound directions.

The auditory map here created is fundamental for reflexes

38
Q

Where is the primary auditory cortex located?

A

superior bank of the temporal lobe

39
Q

How is the AC mapped?

A

tonotopcially.

40
Q

What is the role of the auditory complex?

A

response to complex sounds.

41
Q

Diagram of route of ascending information.

A
42
Q
A

LCRS - neuro (16 decks)

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