Test 2 - Lecture 7 (Auditory) Flashcards
outer ear
collects sounds to focus upon middle ear
middle ear
amplifies the sound energy for conveyance into the inner ear
inner ear
transduces the sound energy into nervous signals
compression
increase in density
rarefaction
reduction in density
quantities of sound (tone and intensity) is from
frequency and amplitude of sound wave
reissner’s membrane
separates the scala vestibuli from the scala media
basilar membrane
separates the scala media from the scala tympani
perilymph
fluid within the scala vestibuli and scala tymapani
endolymph
fluid within the scala media
hair cells
comprise the sensory receptors that transduce sound energy into a neurochemical signal
malleus and incus function as
levers
stapes functions as
piston
oval window is made to
vibrate with the same frequencies and relative amplitudes as the sound waves focused upon the tympanum
compression of the basilar membrane moves it
downward
build in scala tympani - round window bowing outword
rarefaction causes the basilar membrane to displace
upward
lessen the pressure of scala tympani - draws the round window inward
tectorial membrane
cantilevered gelatinous shelf that forms a cover above the hair cells
4 rows of hair cells on basilar membrane
3 rows of outer
1 row of inner
magnitude of the shearing force will vary in direct proportion with the
amplitude of the sound waves
endolymph has high levels of K; creating an
electrochemical gradient (K from endolymph into perilymph)
back and forth K channels opening from the displacement of stereocili is called
mechanosensitive gating
displacement towards the tall
conductance is greater (K channels open - depolarization)
- low basal rate of release (low gCa) glutamate
displacement towards the away
conductance becomes less (K channels are less open - hyperpolarization)
- high rate of release (high gCa) glutamate
low frequencies are detected near the
apex
mid frequencies are detected near the
middle
high frequencies are detected near the
base
tonotopic map
localizing specific frequencies to specific locations along basilar membrane
auditory reception
breaks sounds down into their individual frequency components for transmission into the brain
intensity
firing rate of individual neurons, along with the total number of neurons that are activated
pitch
projection of tonotopic mapping of nervous signals up to the auditory cortex
location in space
localization in the horizontal plane relies upon comparisons of subtle differences in input form the two ears
