Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Module 202 Theme 2 > Physioloy of hearing > Flashcards

Physioloy of hearing Flashcards

1
Q

List the functions of hearing

A

Alerting to dangers
Localising objects
Recognition
Communication via speech

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

At what speed do sound waves travel at?

A

340 m/s

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What are the two attributes of sound?

A

Frequency

Intensity

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What is the frequency range of ideal human hearing:

A

approximately 20-20,000 Hz

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

How does the intensity range of human hearing vary?

A

Intensity range of human hearing varies over 14 orders of magnitude
Intensities >90 dB can lead to permanent hearing damage

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What constitutes the peripheral auditory system?

A

Outer ear, middle ear, cochlea and auditory nerve (part of the VIIIth cranial nerve)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is the middle ear?

A

An impedance matching device: increases pressure ~45x, by the ratio of tympanic membrane and oval window areas, and to a lesser extent by the lever action of the middle ear ossicles

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is the function of the middle ear?

A

Prevents sound from being reflected back from the fluid-filled cochlea

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is ottis media?

A 
Infection or inflammation of middle ear
Usually self-limiting
Common in children
Often from upper respiratory tract infection
Secretory form with effusion
“Glue ear”
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What treatment is available for ottis media and glue ear?

A

If chronic causes a conductive hearing loss
May need draining
Grommets

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What is otosclerosis?

A

Fusion of stapes with oval window
Maybe why Beethoven went deaf
Can be fixed by surgery

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Describe the cochlea

A

Cochlea is a long, coiled, fluid filled tube

Different parts of tube are tuned to different frequencies

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What is the basal end tuned to?

A

high-frequency sound

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What is the apical end tuned to?

A

low-frequency sounds

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What is the Scala vestibuli (SV) connected to ?

A

connected to oval window

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What is the Scala media (SM)?

A

Is a separate chamber

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What is the Scala tympani (ST)?

A

Connected to round window

18
Q

How do the scala vestibuli and scala tympani communicate?

A

SV and ST communicate via helicotrema at apex of cochlea

19
Q

What do the scala vestibuli and scala tympani contain?

A

Scala vestibuli and scala tympani contain perilymph, a normal extracellular fluid with high Na+ and low K+

20
Q

What does the scala media contain?

A

Scala media contains endolymph, an unusual extracellular fluid rich in K+ and low in Na+ (produced by stria vascularis), and an electrical potential of about +80 mV

21
Q

What is the function of the organ of corti?

A

Detects the sound induced motions of the basilar membrane

22
Q

What does the organ of corti contain?

A

Inner and outer sensory hair cells

23
Q

What is the apical membrane of hair cells bathed in?

A

Endolymph

24
Q

What is the basolateral membrane of hair cells bathed in?

A

Perilymph

25
Q

What are the outer hair cells innervated by?

A

Efferent nerve fibres

26
Q

Are the cochlea hair cells regenerated?

A

No

27
Q

Describe mechanotransduction of hair cells

A

Deflection of the hair bundle opens non-selective cation channels, the mechano-electrical transducer (MET) channels, at the lower end of the tip links, between neigbouring stereocilia (‘hairs’)
K+, the major cation in endolymph enters and depolarises the hair cell, driven by its electro-(chemical) gradient [the electrical gradients is +120 to +140 mV; there is little or no chemical gradient]; Ca2+ also enters and causes adaptation
Voltage gated Ca2+ channels open, Ca2+ triggers vesicle release
Afferent nerve fibres (Aff NE) are activated
Inner hair cells are sensory, outer hair cells are sensori-motor cells

28
Q

Describe the electromobility of outer hair cells

A

Outer hair cells amplify basilar membrane motion

Depolarise – shorten; Hyperpolarise – lengthen

Prestin, a modified anion exchanger in the basolateral membrane, is the OHC motor

29
Q

Describe the afferent innervation of the cochlea

A

Neurons in cochlear (spiral) ganglion innervate hair cells and project axons to the brain via the auditory branch of the VIIIth nerve
Each inner hair cell is innervated by axons from 10-20 Type I spiral neurons that signal the reception of sound over a wide range of intensities to the brain
Outer hair cells are innervated by Type II spiral neurons that signal the reception of painfully loud sound that causes cochlear damage to the brain

30
Q

Describe the efferent innervation of the cochlea

A

Efferent fibres from the medial olive innervate the outer hair cells directly
Efferent fibres from the lateral olive synapse on the Type I afferent fibres
Activation of efferent system modifies the sensitivity of the cochlea

31
Q

List the causes of sensorineural hearing loss

A

Noise
Ageing
Ototoxic drugs
Genetic mutations

32
Q

Name some targets of deafness genes in the cochlea

A 
Tight junctions
Gap junctions
Afferent synapse 
Transduction complex
Stria vascularis
Tectorial membrane
33
Q

What are cochlear implants?

A

surgically implanted electronic device that provides a sense of sound to a person who is profoundly deaf

Expensive: limited to the Western world

Results often good enough to recognise and comprehend speech

34
Q

Describe the central auditory system

A

Tonotopically organised

35
Q

Describe the cochlear nucleus

A

Parallel processing starts in cochlear nucleus
Auditory nerve fibres from cochlear ganglion innervate many types of neuron
Neurons extract information about level, onset and timing of sounds

36
Q

Describe the superior olivary complex

A

Two binaural cues are used to localize sounds in space
Interaural level differences are detected in the lateral superior olive (LSO)
Interaural time differences are detected in the medial superior olive (MSO)

37
Q

Describe the inferior colliculus

A

Obligatory synaptic station for all afferents
Laminar organisation in ICC, iso-frequency sheets
Combines complex frequency and amplitude analysis of DCN
with information on sound localization from SOC
May encode complexity and localization of sounds
Auditory reflex centre; reflexive orientation to stimuli

38
Q

Where is the primary auditory cortex located?

A

Primary auditory cortex is located on upper surface of temporal lobe

39
Q

Lesions in auditory cortex cause defects in:

A

sound localisation, discrimination of temporal pattern, intelligibility of speech

40
Q

Lesions in Broca’s (motor aphasia) and Wernicke’s (sensory aphasia) areas

A

Impair the production and comprehension of speech

Module 202 Theme 2 (12 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions