NROC64H3 Lecture Notes - Lecture 4: Hair Cell, Vestibular Duct, Cochlear Nerve
17 Mar 2012
School
Department
Course
Professor
Document Summary
Saq: describe the 3 pathways of the visual system that are differently specialized for motion, colour and shape. Head and body location, head and body movements. Audible variations in air pressure, water, pressure etc. Sound frequency: # of cycles/second expressed in hz. Frequency depends on how many cycles, what the amplitude is. Movement of basilar and tectorial membrane: sheering forces. Lever analogy balancing of the sound greater pressure, ossicles work like levers. Pressure = force/area 20x greater pressure at oval window than tympanic membrane, moves fluids. Attenuation reflex: response where onset of loud sound causes tensor tympani and stapedius muscle contraction. Functions: adapt ear to loud sounds; avoid saturations, damage, filter out low frequency, understand speech better (high freq), reduce sound of our own voice. Perilymph: fluid in sacala vestibuli and scala tympani. Endolymph: fluid in scala media, high k+, stria vascullaris (weird cause other neurons have k+ efflux) Endcochlear potential: endolymph electric potential 80 mv more positive than perilymph.
