Brainscape's Knowledge GenomeTM

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


See full index

neuro lectures > auditory system > Flashcards

auditory system Flashcards

1
Q

what is sound

A

the displacement of air particles following a sinusoidal pattern of compression and rarefaction

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

what does amplitude refer to

A

loudness of sound

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

what do low pitched sounds mean

A

repeat less frequently than high pitched sounds

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

what is the range of human hearing

A

20Hz-20,000Hz
it changes during life

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

at what frequency is the ear most sensitive

A

at 1000 - 4000Hz

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

components of auditory system

A

outer ear - is just movement of air
middle ear - is just movement of air
inner ear - is now movement of fluid
central auditory pathways

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

what does outer ear do

A

helps you collect sound

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

what is the outer ear formed from

A

pinna - cartilaginous structyre
formed from pharyngeal arches 1 and 2
forms between 10th and 18th week in utero

ear canal

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

role of pinna

A

directs sound waves toward ear canal
picks out high pitched sounds more than low pitched

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

describe ear canal

A

1/3 cartilage and 2/3 bone

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

what does middle ear contain

A

bones
muscles
tubes

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

what does middle ear do

A

is for the transmission of sound

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

which bones in middle ear

A

malleus
incus
stapes

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

which muscles in middle ear

A

tensor tympani
stapedius

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

what tube in middle ear

A

eustschian tube

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

what does the middle ear house

A

the ossicular chain

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

what does inner ear do

A

is for the conversion of sound into neural impulses

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

what is the role of the middle ear

A

acoustic impedance match
between air and fluid filled inner ear

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

how much energy loss from air to fluid

A

97%

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

how does the middle ear reduce energy loss

A

it does amplification of the airborne sound vibration = makes it louder
so middle ear is sound amplifier
this increases energy by 200 fold

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

roles of muscles in the middle ear

A

protection of inner ear from acoustic trauma
stiffens the ossicular chain

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

stimulation of stapedius

A

stapedius stimulated acoustically
reflex arc : 3 or 4 neurones
6-7ms reaction time in cats
25ms in man

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

role of tensor tympani

A

voluntary and involuntary control
chewing

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

what is the the role of the eustachian tube

A

ventilation of the middle ear space
drainage of secretions

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

what is inner ear

A

a set of fluid filled sacs, encased in bone

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

what is cochlea responsible for

A

hearing

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

what is labyrinth responsible for

A

balance

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

in elevation of inner ear

A

vestibulochlear. erie

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

structure of cochlea

A

2.5 turns fluid filled bony tube
2 openings - round window and oval window
3 components (scala tympani, scala media & scala vestibuli)
2 ionic fluids

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

where does sound first enter the ear

A

through the pinna (or auricle) which is the exterior part of the ear

It then enters the ear via the external auditory canal/meatus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

what does the shape of both the pinna (or auricle) & external auditory canal/meatus help with

A

helps to amplify and direct the sound

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

what happens to sound after entering the external ear

A

it makes its way through the canal, to the tympanic membrane
(eardrum)

as the air molecules push against the membrane, it causes the tympanic
membrane to vibrate at the same frequency as the sound wave

the membrane vibrates slowly to low frequency sounds and very rapidly to
high frequency sounds

33
Q

what does the tympanic membrane mark

A

the end of the external ear and the start of the middle ear

34
Q

what provides sensation to the middle ear

A

the glossopharyngeal nerve CNIX

35
Q

what is pressure like in the external auditory canal/meatus and middle ear cavity

A

normally equal to atmospheric pressure

36
Q

how is the middle ear exposed to atmospheric pressure

A

via the eustachian tube (or
auditory tube) which connects the middle ear to the pharynx

37
Q

how does the eustachian tube open into the pharynx

A

through a slit-like opening which is
normally closed, EXCEPT when muscle movements result in the opening of
the tube during swallowing, yawning or sneezing

38
Q

what causes a difference in pressure between the middle and external ear

A

changes in altitude

39
Q

what happens to the middle ear when the pressure outside the ear and in the external auditory meatus change

A

the middle ear initially remains constant due to the fact that the eustachian tube is closed

this constant pressure can stretch the tympanic membrane resulting in pain -
which can be relieved by yawning/swallowing which in turn results in the opening of the eustachian tube thereby allowing the pressure in the middle ear to equilibrate with the external atmospheric pressure

40
Q

what happens to the vibrations of the tympanic membrane

A

they are transmitted to the inner ear (for processing) through a moveable chain of three bones - the ossicles (the smallest bones in the body)

41
Q

what are the ossicles

A
  1. malleus
  2. incus
  3. stapes
    (MIS)
    vibrations to the inner ear are transmitted through these bones in this order
42
Q

what is there between ossicles

A

synovial joints

43
Q

what do synovial joints between ossicles do

A

act as a piston and couple the vibrations of the tympanic membrane to the OVAL WINDOW (a membrane covered opening between the middle and inner ear)

44
Q

what happens to the total force of a sound wave applied to the tympanic membrane

A

it is completely transferred to the oval window

However, due to the fact that the oval window is much smaller than the tympanic membrane, the force per area is much greater which is required to adequately transmit the sound energy through the FLUID FILLED COCHLEA

45
Q

how can the amount of energy transmitted to the inner ear be lessened

A

by the contraction of two small muscles in the middle ear - the tensor tympani
& stapedius

46
Q

what innervates tensor tympani

A

V3 (mandibular branch trigeminal)

47
Q

what innervates stapedius

A

CN7 (facial)

48
Q

what does tensor tympani attach to

A

the malleus

49
Q

what does contraction of tensor tympani do

A

dampens the bones movement - innervated by the mandibular division (V3) of the TRIGEMINAL NERVE CN5

50
Q

what does the stapedius attach to

A

the stapes

51
Q

what do tensor tympani and stapedius do as a reflex

A

they act reflexively to CONTINUOUS LOUD NOISE to protect the
delicate receptor apparatus in the inner ear

52
Q

can tensor tympani and stapedius protect the inner ear from SUDDEN INTERMITTENT LOUND SOUNDS

A

no

53
Q

what is the inner ear called

A

the cochlea (the organ of hearing)

54
Q

describe cochlea

A

a spiral-shaped (coiled around 2.5 - 2.75 times), fluid filled space in the temporal bone

55
Q

what is the cochlear duct

A

a membraneous tube that completely divides the cochlea lengthwise

56
Q

what does the cochlear duct contain

A

the sensory receptors of the auditory
system

57
Q

what is the cochlear duct filled with

A

a fluid called endolymph - a compartment of extracellular fluid containing a high concentration of K+ and a low concentration of Na+ (this arrangement of concentrations is normally seen in intracellular fluid)

On either side of the cochlear duct are compartments filled with perilymph, which is similar in composition to
cerebrospinal fluid (CSF)

58
Q

where is the scala vestibuli

A

above the cochlear duct

begins at the oval window

it forms the entrance to the inner ear
from the oval window

59
Q

where is the scala tympani

A

below the cochlear duct and
connects to the middle ear
via a second-membrane covered opening, the round window

60
Q

where are the scala vestibuli and scala tympani continuous

A

at the far end of the cochlear duct
at the helicotrema

61
Q

what movement creates waves of
pressure in the scala vestibuli

A
  1. sounds waves from the external acoustic meatus cause the tympanic membrane to move in and out which in turn is transmitted to the ossicles
    which in turn transmit this
    movement to the oval window
  2. this results in the oval window
    moving in and out of the scala
    vestibule
62
Q

where are the waves of pressure from the scala vestibuli transmitted to

A

the majority are transmitted across the cochlear duct with some being transmitted toward the helicotrema and into the scala tympani where the pressure is relieved by the movements of the membrane of the round
window

63
Q

what does the basilar membrane form

A

the side of the cochlear duct closest to
the scala tympani

64
Q

what does the organ of corti contain

A

the ears sensitive receptor cells,
- pressure difference across the duct causes the basilar membrane to vibrate

65
Q

describe the base of the basilar membrane

A

narrow & stiff and thus sensitive to high
frequencies

66
Q

describe the apex of the basilar membrane

A

wider & less stiff and thus is sensitive to
low frequencies

67
Q

what are hair cells

A

the receptor cells of the
organ of corti

are mechanoreceptors that have hairlike stereo-cilia protruding
from one end

68
Q

what can damage the stereocilia of the hair cells

A

some antibiotics

69
Q

how many anatomically separate groups of hair cells are there an what are they

A

2

inner hair cells
outer hair cells

70
Q

how many rows of inner hair cells are there

A

a single row

71
Q

how many rows of outer hair cells are there

A

4-5 rows

72
Q

describe the stereocilia of inner hair cells

A

extend into the endolymph fluid and
convert pressure waves caused by the movement of fluid in the cochlear duct
into receptor potentials

73
Q

describe the stereocilia of outer hair cells

A

are embedded in the overlying
tectorial membrane and mechanically alter its movement to sharpen frequency tuning at each point along the basilar membrane

74
Q

what causes bending of the stereocilia

A
  • the tectorial membrane overlies the
    organ of corti
  • as the pressure waves displace the basilar membrane
  • the hair cells move in relation to the
    stationary tectorial membrane
  • causing bending of the stereocilia
75
Q

what happens when the stereocilia bend towards the tallest member of the bundle

A
  • fibrous connections called TIP LINKS pull open mechanically gated K+ channels,
  • resulting in an influx of K+ from the
    surrounding endolymph (K+ rich)
    thereby depolarising the membranes
  • this change in voltage triggers the
    opening of voltage-gated Ca2+
    channels near the base of the cell,
  • which in turn triggers neurotransmitter release (since Ca2+ causing neurotransmitter containing vesicles to migrate to the presynaptic membrane)
76
Q

what happens when hair cells bend away from the tallest member of the bundle

A
  • slackens the tip links
  • thereby closing the channels and
    allowing the cell to rapidly repolarize
  • hair cells release glutamate
  • which in turn binds to and activates protein binding sites on the terminals of the afferent neurones
77
Q

what results in the generation of action potentials in neurones

A

as sound waves vibrate the basilar membrane, the stereocilia are bent back and forth, the membrane potential of the hair cells rapidly oscillates and bursts of glutamate are released onto afferent neurones

the axons join to form the COCHLEAR BRANCH of the VESTIBULOCOCHLEAR NERVE (CN VIII)

78
Q

what does greater energy of the sound wave (loudness) mean

A

the greater the energy (loudness) of the sound wave, the greater the
frequency of action potentials generated in the afferent nerve fibres

79
Q

why does each hair cell respond to a
limited range of sound frequencies

A

due to its position on the basilar membrane

one particular frequency will stimulate it most strongly

neuro lectures (15 decks)

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