Hearing Part 1

Question 1

What is the general pathway of the auditory system (ear pathway)?

Answer 1

outer ear –> inner ear –> mechanical force of sound transduced into neural activity (action potentials)

Question 2

What is transduction?

Answer 2

Conversion of one form of energy to another

Question 3

What are the sections of the external ear?

Answer 3

Pinna, ear canal

Question 4

What are the sections of the middle ear?

Answer 4

tympanic membrane, ossicles, oval window

Question 5

What are the sections of the inner ear?

Answer 5

Cochlea (subsections = scala vestibula, scala media (Organ of Corti), scala tympani)

Question 6

What part of the ear captures, focuses, and filters sound?

Answer 6

External ear

Question 7

What is the external part of the ear, ridges/valleys modify character of sound?

Answer 7

Pinna

Question 8

What is the ear canal?

Answer 8

tube leading from pinna to tympanic membrane, sound waves funnel through

Question 9

What part of the ear concentrates sound energies; collection of tiny membranes, muscles, and bones (little microphone) that links ear canal to inner ear

Answer 9

middle ear

Question 10

What is the tympanic membrane (eardrum)?

Answer 10

partition between external ear and inner ear that vibrates with same frequency as sound

Question 11

What are the ossicles?

Answer 11

three small bones (incus, malleus, stapes) that transmit and amplify vibration across the middle ear (from tympanic membrane to oval window) - like a chain of bones

Question 12

What is the specialized patch of membrane that receives vibrations from the tympanic membrane through the ossicles

Answer 12

Oval window

Question 13

What is the cochlea?

Answer 13

snail shaped structure in inner ear canal that contains primary receptor cells for hearing

Question 14

What are the three channels in the cochlea?

Answer 14

Scala vestibuli (vestibular canal), scala media (middle canal) contains OoC, scala tympani

Question 15

What is the Organ of Corti?

Answer 15

in scala media, converts vibrations from sound into neural activity; lies on basilar membrane of cochlea + contains hair cells and auditory nerve terminals

Question 16

What are the hair cells of the OoC?

Answer 16

receptor cells of hearing, stereocilia on top, transduce vibrational nrg into neural activity

Question 17

What are sterocilia?

Answer 17

tiny bristle (hair) that protrudes from a hair cell in the auditory/vestibular system

Question 18

What is basilar membrane?

Answer 18

in OoC, contains principle structure for auditory transduction

Question 19

What is the gelatinous membrane at top of OoC?

Answer 19

tectorial membrane

Question 20

What is the pathway from the middle ear to inner ear?

Answer 20

tympanic membrane vibrates –> ossicles move –> vibrations transferred to oval window –> waves in liq of scala vestibuli and scala tympani –> basilar membrane ripples

Question 21

What is the pathway for the ion channels in relation to auditory system?

Answer 21

basilar membrane ripples –> stereocilia bent –> mechanical ion channels open
(K+ enters –> depolarizes –> Ca+2 enters –> synaptic vesicles fuse –> ntrans released)

Question 22

What are the roles of IHC and OHC?

Answer 22

inner/outer hair cells, contacted by axons from vestibulocochlear nerve (CN VIII)

Question 23

What axons send info to the brain?

Answer 23

afferents

Question 24

What axons bring info from the brain?

Answer 24

efferents