Auditory Flashcards
(98 cards)
1
Q
define audition
A
sense of hearing
2
Q
describe general functions of audition
A
Mechanisms within the ear and brain that translate sound in our environment into meaningful neural signals
3
Q
define sound
A
audible variations in air pressure
4
Q
how is sound created?
A
molecules are displaced forward leaving a corresponding area of pressure
5
Q
How do sound waves vary in two ways?
A
they either run in amplitude or frequency
6
Q
define amplitude
A
intensity; peak to trough;
perceived as differences in loudness
7
Q
define frequency
A
# of compressions per second pitch
8
Q
name the 3 main divisions of the ear
A
Outer
Middle
Inner
9
Q
What does the outer ear contain?
A
Pinna Auditory canal (external auditory meatus)
10
Q
define Pinna
A
Funnel shaped outer ear made of skin and cartilage
11
Q
what does the Pinna actually do?
A
the funnel shape of the pinna helps collect sound waves and direct them toward the external auditory meatus
12
Q
define auditory canal
A
channel leading from the pinna to the tympanic membrane
13
Q
what is the auditory canal lined with?
A
hairs and ceruminous glands
14
Q
what do the ceruminous glands produce?
A
cerumen
15
Q
define cerumen
A
its a modified sebum (earwax) which helps prevent foreign objects from reaching the tympanic membrane
16
Q
what is the main function of the auditory canal?
A
it opens into pharynx and equalizes air pressure between outside ear and middle ear cavity
17
Q
what does the middle ear consist of?
A
tympanic membrane
ossicles
18
Q
the middle ear is a ______ chamber
A
air-filled
19
Q
the tympanic membrane can also be called…
A
the eardrum
20
Q
the tympanic membrane is ______ and _____ shape
A
semitransparent
oval
21
Q
the tympanic membrane moves in response to what?
A
variations in air pressure
22
Q
name the three layers of the tympanic membrane
A
simple cuboidal epithelium on the inner surface
a thin stratified squamous epithelium on the outer surface
a layer of CT between them
23
Q
what is does the tympanic membrane separate?
A
the external ear from the middle ear
24
Q
define ossicles
A
a series of bones in a small air filled chamber
25
what is the main function of the ossicles?
to transfer the movement of the tympanic membrane into the movement of a second membrane covering a hole in the bone of the skull
26
name this hole
oval window
27
name the bones of the middle ear
Malleus
Incus
Stapes
28
the stapes sits on top of what?
the oval window
29
more force is required to displace ___ than air
fluid
30
so then what do the bones do?
they amplify the pressure
31
what is displaced in response to the movement of the tympanic membrane?
malleus
32
what does this lead to?
the top of the incus is pushed towards the outer ear and pushes the bottom towards the inner ear
33
what happens next?
the stapes is consequently pushed forward against the oval window which is compressed inward
34
the eustachian tube connects what?
the air-filled middle ear to the mouth
35
the inner ear is ____ filled.
fluid
36
what happens in the inner ear?
this is where physical movement of the oval window is converted into neural signal.
37
where does this "conversion" exactly take place?
cochlea
38
the cochlea also contains this structure which is not part of the auditory system but is involved in balance.
vestibular apparatus and the semicircular canals
39
what does the cochlea do?
is transduces the mechanical displacement of the oval window into a neural signal
40
name the main components of the cochlea
```
scala vestibuli
scala tympani
scala media
organ of corti
basilar membrane
fluid
```
41
the organ of corti contains...
auditory receptor cells
42
where is the organ of corti located?
in the scala media
43
what does the basilar membrane do?
it separates scala media and scala tympani
44
fluid is continuous between what?
scala vestibuli and scala tympani
45
the organ of corti contains this membrane
tectorial membrane
46
the tectorial membrane has...
both thick and thin sides
47
what can be found under the tectorial membrane?
stereocilia
48
what are the 2 types of hair cells found under the tectorial membrane?
outer hair cells
| inner hair cells
49
mechanical force pushes on...
the oval window
50
fluid within the cochlea is _______
incompressible
51
so this means...
the fluid is pushed forward
52
how does this conserve the wave properties of the sound
the movement of the fluid has frequency and amplitude
53
what does this cause?
causes the round window to bulge out
54
structures within the cochlea are....
not rigid
55
_______________ is flexible and bends inn response to sound
basilar membrane
56
the basilar membrane is ___ at apex than base
wider
57
stiffness of the membrane decreases from...
base to apex
58
this resembles a what?
a diving board
59
what doe high frequency sounds have?
higher energy and can displace the stiffer part of the basilar membrane (near base)
60
lower frequency sounds have..
lower energy and displace the apex end
61
____ responds to high frequency and the ___ responds to low frequency
base
| apex
62
basilar membrane establishes a place code in which...
different locations are maximally deformed in response to different frequency sounds
63
name the structures found in the organ of corti
```
outer hair cell
inner hair cell
tectorial membrane
reticular membrane
basilar membrane
stereocilia
spiral ganglion
```
64
of all those structures, which are involved as auditory receptors?
hair cells
| stereocilia
65
what is a critical event in the transduction of sound into neural signal
bending of these cilia
66
what does the hair do?
it extends above the reticular membrane and come in contact with the tectorial membrane
67
what happens when the basilar membrane moves in response to the motion of the stapes?
the whole complex moves as a unit either towards or away from the tectorial membrane and the lateral motion of the reticular membrane bends the sterocilia
68
if the hair gives a downward phase, what happens?
hyperpolarization (closed channel)
69
if the hair gives an upward phase, what happens?
depolarization (opened channel and K+ can enter)
70
changes in cell potential result in what?
the opening of K+ channels on the tips of the stereocilia
71
the response of the depolarization is...
Ca++ channel is activated
72
what does this influx of Ca++ lead to?
causes the release of synaptic vesicles from the end of the hair cell
73
describe the sequence of the displacement of basilar membrane.
1. physical displacement of the basilar membrane bends the stereocilia
2. bending of the cilia either opens or closes a K+ channel
3. When K+ enters, the hair cell depolarizes
4. Depolarization activates a Ca++ channel
5. Ca++ influx causes NT release
74
where do the action potentials occur at?
the level of the output ganglion
75
multiple outer hair cells make...
synaptic contact with a single ganglion cell
76
what does the ganglion do next?
it makes a synaptic contact with a single inner hair cell
77
what is the most abundant hair cell?
the outer hair cell
78
what do these outer hair cells do?
it alters the stiffness of the tectorial membrane
79
there are two cochlea, each projecting to its...
cochlear nucleus
80
within the cochlear nucleus this process branches...
dorsal cochlear nucleus
posterior ventral cochlear nucleus
anterior ventral nucleus
81
what do the dorsal and posterior ventral cochlear nuclei do?
they send efferent projections to the contralateral inferior colliculus
82
how does it do this?
via the nucleus of the lateral leminiscus
83
what does the anterior ventral cochlear nucleus permit?
the detection of interaural time differences
84
the medial superior olive (MSO) has cells that...
receive coincident innervation from the right and left anteroventral cochlear nucleus
85
the length of the axonal connections determine...
which MSO cell receives coincident activation by action potential
86
the anteroventral cochlear nucleus projects directly...
to the ipsilateral lateral superior olive (LSO)
87
the anteroventral cochlear nucleus projects indirectly to the...
contralateral lateral superior olive
88
how does this occur?
via the inhibitory neuron originating in the medial nucleus of the trapezoid body
89
the anteroventral cochlear nuclear firing rate is greater for sound when...
the sound has higher intensity
90
when do LSO firing be the highest on that side?
when the sound arises directly lateral on the same side to the listener
91
____________ from the ipsilateral anteroventral cochlear nucleus will be maximal
excitation
92
__________ from the contralateral MNTB will be minimal
inhibition
93
where does the dorsal and posteroventral cochlear nuclei send projections?
to the inferior colliculus
94
the highly processed auditory information is then relayed to the...
medial geniculate nucleus of the thalamus
95
from the thalamus, this information ascends to the...
primary auditory cortex
96
where is the primary auditory cortex located?
in the temporal lobe
97
frequency is a consequence of what?
the mechanics of the basilar membrane
98
name the steps of basic auditory pathway
1. sound waves move tympanic membrane
2. tympanic membrane moves ossicles
3. ossicles move membrane at the oval window
4. motion at the oval window moves fluid in the cochlea
5. movement of the fluid in the cochlea causes a response in sensory neurons
6. signal is transferred and processed by a series of nuclei in the brain stem
7. information is sent to a relay in the thalamus
8. MGN projects to the primary auditory cortex in the temporal lobe
