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Unit 2: Nervous System. Hearing Notes. (1) Ear Design. Ear is like a well designed funnel. Sound waves spiral down into auditory canal. Sound Waves smack against ear drum (tympanic membrane). (2) Vibrations. Sound Waves Tympanic Membrane Eardrum literally like the leather on a drum
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Unit 2: Nervous System Hearing Notes
(1) Ear Design • Ear is like a well designed funnel. • Sound waves spiral down into auditory canal. • Sound Waves smack against ear drum (tympanic membrane).
(2) Vibrations • Sound Waves Tympanic Membrane • Eardrum literally like the leather on a drum • T-Membrane Hammer Anvil Stirrup • Hammer, Anvil and Stirrup are very small bones in inner ear • Stirrup Oval Window Inner Ear Fluid
(3) Cochlea • Cochlea = Snail like structure in inner Ear. • Contains Organ of Corti: • Contains hearing receptors / hair cells • Hair cells stimulated by movement of Inner Ear Fluid • Basilar Membrane • Type of membrane on specific receptors • Responds to changes in pitch • Fluid Receptors Cochlear Nerve Brain
(4) Equilibrium & Balance • Your ears keep track of your body’s position. • Equilibrium receptors lie within the inner ear of your ears (Vestibular Apparati). • 2 Types of Equilibrium: • Static • Dynamic
(5) Static Equilibrium • Head Balance • Static Receptors = Maculae: • On top of maculae lies the otolithic membrane (gel-like) • Head Moves Otoliths Moves! • Movement of Otolithic Receptor Impulse to Vestibular Nerve & Brain • Tells your brain when your head is not upright.
(6) Dynamic Equilibrium • Rotation & Angles of Head • Semicircular Canals of Cochlea: • Contain receptors = Crista Ampullari • Crista Ampullari contain receptor hairs, endolymph fluid and a capula cap • Body Movement endolymph movement Push on Capula Cap Receptor Hairs Vestibular Nerve & Brain
(7) Motion Sickness • Inefficient dynamic equilibrium… • Semicircular Canals either too sensitive or too slow at sending messages • Too many visual messages • Too many inner ear messages • Visual conflicts with Inner Ear • Unique to each individual
(8) Deafness • Deaf= Any hearing loss • Types: • Conduction • Sensorineural
(9) Conduction Deafness • Something Blocks Tympanic Membrane • Sound Waves cannot reach Ear Drum + Inner Ear • Causes: • Ear Wax • Ruptured Ear Drum • Injured Hammer, Anvil and/or Stirrup • Usually Temporary, Solved by Surgery
(10) Sensorineural Deafness • Damage to actual parts of ears: • Receptor Cells • Cochlea • Vestibular Nerve • Can be hereditary, damage from disease/virus, damage from loud noises • Often permanent