BIOS1171 Lecture Notes - Lecture 17: Sensorineural Hearing Loss, Otolith, Brainstem
22 Aug 2018
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Document Summary
Propagation through middle ear: vibration of tympanic membrane ossicle vibration oval window vibration, sound vibrations are amplified in the middle ear as the. L tympanic membrane has a bigger surface area than the oval window; also the ossicles act as a lever system to also aid amplification. Oval window r- l r- l r- l: impedance matching: ensures vibrations in liquid-filled inner ear match those in air- M e c h a n ic a l e v e n ts in in n e r e a r. Basilar membrane: basilar membrane vibration: loudness coded by amplitude. Distance from oval window (mm) ed by ch tion. Transduction: sequence, bending of hair cell, hair cell depolarisation, release of neurotransmitter, increased rate of ap in axon. Deafness: conduction deafness: middle ear deficit (e. g. otosclerosis, nerve deafness: inner ear deficit; aka sensorineural deafness (e. g. presbycusis old age hearing) Vestibular system components: otolith organs: sense linear acceleration, semicircular canals: sense rotational acceleration.
