unit 2 review - auditory Flashcards
name the order of the osssicles?
malleus
incus
stapes
what does the stapes do?
pushes on the oval window to displace cochlear fluid
sound wave pathway? (up to oval window)
1) auditory canal
2) tympanic membrane
3) ossicles
4) oval window
what is impedance matching?
how sound waves are amplified
muscles that aid in the attenuation reflex?
tensor tympani
stapedius
how does the cochlea send messages to the brain?
the auditory vestibular nerve
what does the stapes do when it presses against the oval window?
displaces fluid
list the fluid filled compartments in the cochlea and their associated windows?
and fluid
scala vestibuli (oval window) = perilymph
scala media = endolymph
scala tympani (round window) = perilymph
what does the reissners membrane do?
seperates the scala vestibuli and scala media
what does the organ corti contain, where is it located?
sits on top of the basilar membrane
where is the tectoral membrane located?
it hangs over the organ of corti
what fluid is high in K+ vs. low?
endolymph is high in K+
what maintains the concentrations of the fluid in the ear?
stria vascularis
describe the tonotopy of the base?
base=stiff and narrow
apex=wide and floppy
- high to low frequency
inner hair vs outer hair cells
- number
- ratio
ration = 1:3
inner = 4k
outer = 12k
what do hair cells synapse onto?
spiral ganglion cells
where do the axons of spiral ganglion cells project?
to the auditory nerve
what are inner hair cells involved with versus outer hair cells?
what makes each move?
inner: input to the auditory-vestibular nerve
- moved by endolymph
outer: cochlear amplification
- moved by tectorial membrane
what happens when the basilar membrane moves up?
what happens when it moves down?
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
what is the resting state of Tip-link K+ channels
what happens when they bend towards kinocilium vs. away
normal state
- half closed, half open
towards kinocilium
- channels open more
- depolarization
towards kinocilium
- channels close
- hyperpolarize
what does depolarization do to VGCa+ channels in the auditory system?
- opens them
- glu is released in graded synapse
- glu affects spiral ganglion, which causes AP
prestin?
changes the length of the outer hair cells
- furosemide inactivates OHC motor proteins
where is auditory stimuli mononural?
where do they converge and become binural?
- mono at cochlear nuclei
- bi at superior olive
how is high intensity encoded? (2)
bm vibrates more, hair cells oscilate more
- more depolarization=more AP
bm is displaced more
- more hair cells activate=more AP
how is frequency encoded? (2) low vs. high freq
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
sound localization methods? (2) low vs. high freq
high
- interneural intensity difference
low
- interneuaral time delay
what is the first area to receive input from both ears?
superior olive
how is sound localized vertically?
pinna
