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