University:
Camosun College
Course:
BIOL 252 | Pathophysiology for Nursing 1
Academic year:

2024
Views:

356

Pages:

2
Author:

Aysha A.

Physiology of Audition Anatomy of Ear: External Ear Middle Ear Inner Ear Oval Window Round Window From tympanic membrane to oval window, ear ossicles are involved: Malleus Incus Stapes (Footplate attached to oval window) Impedance Matching: Decibels (dB) measure the pressure of sound: Low dB → Low pressure High dB → High pressure For a Sound to Be Audible: Pressure waves should be relative to hit the Tympanic Membrane (TM) TM sets subsequent waves External & middle ear → Air-filled cavity Inner ear has cochlea → Fluid-filled cavity Difference in pressure between air medium and fluid medium necessitates impedance to conduct sound. Impedance matching is done by the middle ear. Events of Impedance Matching: Sound from a wide range of area converges into the oval window. The convergence amplifies the sound (pressure is enhanced by conducting pathways). Carried out by a difference in surface area of tympanic membrane and oval window. Footplate of stapes kicks on the oval window. Inner Ear / Cochlea: 3 Semicircular Canals (SCC): Superior Posterior Lateral SCC are involved in maintaining equilibrium. Cochlea is composed of 3 labyrinths: Scala Vestibuli (S. Vestibuli) Scala Media (S. Media) Scala Tympani (S. Tympani) (Small opening) S. Vestibuli and S. Tympani communicate at the apex through Helicotrema. Perilymph: Present in S. Vestibuli and S. Tympani Identical to plasma Endolymph: Present in S. Media High in K+ and low in Na+