sensory transduction

three compartments of the cochlea include [ ], [ ], and [ ]

scala vestibuli

scala tympani

scala media

the scala vestibuli and scala tympani both include

perilymph

the scala media contains [ ] which is unusual » it has a very high K+ creating a huge electrochemical gradient

endolymph

the [ ] separates the compartments of the cochlea and moves when sound enters

basilar membrane

sound causes [ ] that flex the basilar membrane

pressure waves

the [ ] detects high-frequency sounds

base

the [ ] detects low-frequency sounds

apex

the wave travels along the membrane; how far it goes depends on frequency

the [ ] contains hair cells

Organ of Corti

the outer hair cells are composed of [ ] rows and the inner hair cells are made of [ ] row

three

one

each hair cells has around [ ] that arranged by height

100 stereocilia

stereocilia tips are connected by [ ]

tip links (tiny protein springs)

the [ ] is above the stereocilia tips

tectorial membrane

how does sound become an electrical signal

the basilar membrane moves causing sterocilia to bend towards the tallest cilia

tension on tip links opesn mechanosensitive TRP channels

the channels allow potassium to rush into the hair cell

potassium influx depolarizes the cell

depolarization opens voltage gated Ca2+ channels

Calcium influx triggers vesicle fusion releasing glutamate

bending towards the shortest cilia relaxese tip links stopping neurotransmitter release

the hair resting potential is

~45 to -60mV

when TRP channels open, potassium has a massive driving force to enter the cell depolarizing the hair cell

microphone

picks up sound

processor

codes frequency/intensity

electrode array

stimulates spiral ganglion axons

found in scala tympani

electrodes are arranged so high frequencies stimulate the base and low frequencies the apex

in hair cells EK is [ ] because of endolymph composition

positive