Hair cells/rest of unit

stereocilia of outer hair cells imbedded in

the tectorial membrane

outer hair cells also called

stereocilia

endolymph has more

potassium

perilymph has more

sodium

stapes away from cochlea, basilar membrane upward, hair cells away from center=

rarefaction and depolarization

stapes towards cochlea, basilar membrane downward, hair cells toward center =

condensation and hyperpolarization

endocochlear potential

80 mV

haircells

-70 mV

total difference between endocochlear and hair cells mV =

150 mV

action potential

potassium cycles through hair cells and generates potentials in hair cells which stimulate the neurotransmitter

inner hair cell function

signal transmission

outer hair cell function

cochlear amplification

frequency discrimination

sound wave travels in cochlea and amplitude increases/becomes sharper

20,000 hz at

base

20 hz at

apex

place theory= to

tonotopic organization

direct current

continuous movement of BM till we die

alternating current

can change when spooked

inner and outer hair cells connected to auditory nerve at its

base

auditory nerve =

cranial nerve # 8

cranial nerve 7 and 8

work together

afferent =

bottom to top

efferent =

top to bottom

type 1 hair fibers

inner hair cells (signal transmission to brain) 90-95% of all fibers

type 2 hair fibers

outer hair cells = amplification (5-15% of nerve fibers

auditory nerve is connected at the ____ of the cochlea

apex

neural threshold =

softest sound we can detect

saturation =

max point energy can go

high saturation =

lower threshold (more sensitive to sound)

lower saturation =

higher threshold (less sensitive to sound)

phase locking

helps amplify low frequency sounds

2 tone inhibition

added sound tone can decrease first tone (interference)

ipsilateral

same side

contralaeral

opposite sides