BILD 2 Chapter 38: Ch 38 Sensory Systems Study Guide
8 Dec 2015
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Document Summary
The three bones of the middle ear transmit the vibrations to the oval window (membrane on the cochlea surface). When the stapes vibrates against the oval window, it creates pressure waves in the perilymph in the cochlea. When entering the vestibular canal, the pressure waves push down on the cochlear duct and basical membrane. The basilar membrane and attached hair cells vibrate up and down. Hairs projecting from moving hair cells are deflected by tectorial membrane, and with each vibration, hairs bend in one direction and the other. This causes opening/closing of ion channels in hair cells and thus a change in auditory nerve sensations. This activates rhodopsin, which activates transducin, which activates phosphodiesterase which detaches cgmp from na+ channels, hydrolyzing it to gmp and causing channels to close. There are three types of cones (opsin proteins). Each has a different sensitivity across the visible spectrum, providing optimal response to red, green or blue light.
