BIOM2015 Lecture Notes - Lecture 10: Tectorial Membrane, Oval Window, Perilymph
Saturday, 12 May, 2018
Hearing
Sound wave travel pathway
pinna -> ear canal (External Acoustic Meatus) -> Ear drum/tympanic membrane ->
Ossicles (M,I,S) (connect with joints) -> oval window -> cochlea (perilymph endolymph) -
> brain
vibration transmission decrease in old age due to joint connecting mis is declined
when sound waves vibrate ear drums and travel sound waves along MIS to oval window,
perilymph of cochlea depress the endolymph, vibration get transmitted makes the whole
tectorial membrane vibrates. Organ of Corti is displaced and the hair cells moved.
Vibration high frequency bent hair cells quicker detected earlier in cochlea
round window to middle ear is where vibration ended and escape
high frequency make tectorial membrane vibrates earlier
Organ of corti contains hair cells and tip of the hair cells are embedded in tectorial
membrane
Outer Hair Cells Inner Hair Cells
Outer hair cells contains little contractile units which can vibrate in the same frequency
as inner hair cell to amplifying vibrations of inner hair cells so we can hear clearer
Only Inner hair cells activation will cause sound perception send information to brain
Brain sense the action potential information send from inner hair cells, get signal from
brain through motor nerves to outer hair cells of tectorial membrane
too shallow sound waves with high frequency will not activate inner hair cells no sound
can be heard (soft high pitch)
Tip links and ion channels
Tip links pulled in 1 direction opens the ion channels which K+ goes in the cell; if graded
potential is enough; voltage gated ion channels will open and Ca2+ flush in which
release neurotransmitters from vesicles; neurotransmitters will release to synaptic cleft
which enough neurotransmitters will cause nerve to depolarise and generate another
action potential send signals to brain
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Document Summary
Sound wave travel pathway pinna -> ear canal (external acoustic meatus) -> ear drum/tympanic membrane -> Ossicles (m,i,s) (connect with joints) -> oval window -> cochlea (perilymph endolymph) - Organ of corti is displaced and the hair cells moved. Vibration high frequency bent hair cells quicker detected earlier in cochlea round window to middle ear is where vibration ended and escape high frequency make tectorial membrane vibrates earlier. Organ of corti contains hair cells and tip of the hair cells are embedded in tectorial membrane. Outer hair cells contains little contractile units which can vibrate in the same frequency as inner hair cell to amplifying vibrations of inner hair cells so we can hear clearer. Only inner hair cells activation will cause sound perception send information to brain. The higher the frequency the higher the pitch. The larger the amplitude the louder the sound.
