Inner Ear function – A brief summary –


the organ of Corti is located in the
cochlea a spiral 3 chambered snail like structure within a bony matrix the organ of corti extends from the
anterior part of the vestibule and coils for about
two-and-a-half turns around a bony pillar called the modiolus
in cross-section is this scala media this houses the
organ of Corti which is referred to as the receptor
organ of hearing the Scala media is filled with endolymph
the scala media include stretches from the Tectoral membrane, basilar membrane and hair cells which sense the
mechanical forces there are two kinds of hair cells inner and outer hair cells them ninety-five percent the afferent
fibers are from the inner hair cells outer hair
cells receive mostly efferent input the filamentous structures that connects
the tips of adjacent stereocilia are known as tip-links these are thought
to amplify the forces in the area of the molecular sensors how does sound enter the Cochlea :
compression hits the Tympanic membrane causing the Stapes to transfer
force to the oval window from there sound moves to the round
window high frequencies are encoded at the base all and low frequencies at the apex it is this property that leads to the
time the tonotopic map along the basilar membrane the manner in which the basilar
membrane vibrates in response to sound is the key to
understanding cochlear function the hair cells are located between the
Tectorial membrane and Basilar membranes and are stimulated by the shearing force
between the two caused by the pivot point of the two
membranes the apical portion of the hair cell is
based in high potassium solution and the base of the hair cell is bathed in
potassium poor solution this establishes the potassium flow through
the cell is used for both de-polarization
potassium in at the apex and re-polarization: potassium out at the
base of the hair cell the hair cells convert
vibrations into neural impulses sent to the brain your brain then interprets these nerve
impulses as sound

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