unit 2 review - auditory

Question 1

name the order of the osssicles?

Answer 1

malleus
incus
stapes

Question 2

what does the stapes do?

Answer 2

pushes on the oval window to displace cochlear fluid

Question 3

sound wave pathway? (up to oval window)

Answer 3

1) auditory canal
2) tympanic membrane
3) ossicles
4) oval window

Question 4

what is impedance matching?

Answer 4

how sound waves are amplified

Question 5

muscles that aid in the attenuation reflex?

Answer 5

tensor tympani
stapedius

Question 6

how does the cochlea send messages to the brain?

Answer 6

the auditory vestibular nerve

Question 7

what does the stapes do when it presses against the oval window?

Answer 7

displaces fluid

Question 8

list the fluid filled compartments in the cochlea and their associated windows?
and fluid

Answer 8

scala vestibuli (oval window) = perilymph
scala media = endolymph
scala tympani (round window) = perilymph

Question 9

what does the reissners membrane do?

Answer 9

seperates the scala vestibuli and scala media

Question 10

what does the organ corti contain, where is it located?

Answer 10

sits on top of the basilar membrane

Question 11

where is the tectoral membrane located?

Answer 11

it hangs over the organ of corti

Question 12

what fluid is high in K+ vs. low?

Answer 12

endolymph is high in K+

Question 13

what maintains the concentrations of the fluid in the ear?

Answer 13

stria vascularis

Question 14

describe the tonotopy of the base?

Answer 14

base=stiff and narrow
apex=wide and floppy
- high to low frequency

Question 15

inner hair vs outer hair cells
- number
- ratio

Answer 15

ration = 1:3
inner = 4k
outer = 12k

Question 16

what do hair cells synapse onto?

Answer 16

spiral ganglion cells

Question 17

where do the axons of spiral ganglion cells project?

Answer 17

to the auditory nerve

Question 18

what are inner hair cells involved with versus outer hair cells?
what makes each move?

Answer 18

inner: input to the auditory-vestibular nerve
- moved by endolymph

outer: cochlear amplification
- moved by tectorial membrane

Question 19

what happens when the basilar membrane moves up?
what happens when it moves down?

Answer 19

moves up
- reticular lamina moves up towards tectorial membrane
- stereo-cilia shift away from modilus

moves down
- reticular lamina down away from tectorial membrane
- stereo-cilia shift towards modilus

Question 20

what is the resting state of Tip-link K+ channels
what happens when they bend towards kinocilium vs. away

Answer 20

normal state
- half closed, half open

towards kinocilium
- channels open more
- depolarization

towards kinocilium
- channels close
- hyperpolarize

Question 21

what does depolarization do to VGCa+ channels in the auditory system?

Answer 21

• opens them
• glu is released in graded synapse
• glu affects spiral ganglion, which causes AP

Question 22

prestin?

Answer 22

changes the length of the outer hair cells
- furosemide inactivates OHC motor proteins

Question 23

where is auditory stimuli mononural?
where do they converge and become binural?

Answer 23

• mono at cochlear nuclei
• bi at superior olive

Question 24

how is high intensity encoded? (2)

Answer 24

bm vibrates more, hair cells oscilate more
- more depolarization=more AP

bm is displaced more
- more hair cells activate=more AP

Question 25

how is frequency encoded? (2) low vs. high freq

Answer 25

tonotopy (high freq)
- basliar mem
- isofrequency bands

timing (low freq)
- phase locking, firing at the same time as sound wave
- volley principle, neurons firing at the same phase

Question 26

sound localization methods? (2) low vs. high freq

Answer 26

high
- interneural intensity difference

low
- interneuaral time delay

Question 27

what is the first area to receive input from both ears?

Answer 27

superior olive

Question 28

how is sound localized vertically?

Answer 28

pinna