Physiology of the auditory system

Question 1

What is intensity in a sound wave determined by?

Answer 1

amplitude

Question 2

What is pitch in a sound wave determined by?

Answer 2

frequency

Question 3

What is timbre?

Answer 3

qulity of the sound

Question 4

What is impedence matching?

Answer 4

high impedence of fluid in the cochlea so middle ear bones overcome the loss of sound by increasing the sound pressure

Question 5

What are the three mechanisms for impedence matching?

Answer 5

area ratio of the ear drum to the stapes footplate; lever action of the ossicles-arm of malleus is longer than incus; buckling of the ear drum

Question 6

What is foudn in the floor of the scala media?

Answer 6

basilar membrane which contains the organ of corti

Question 7

What is found in the ceiling of the scala media?

Answer 7

reissners membrane

Question 8

What two areas are separated by reissners membrane?

Answer 8

scala vestibuli and scala media

Question 9

What 2 areas are separated by the basilar membrane?

Answer 9

scala media and scala tympani

Question 10

What area is connected to the round window?

Answer 10

scala tympani

Question 11

Where do the scala tympani and scala vestibuli connect?

Answer 11

helicotrema

Question 12

What determines the distance a particular frequency travels?

Answer 12

the width and flexibility of the basilar membrane

Question 13

How does the basilar membrane change as you go through the cochlea?

Answer 13

gets thinner and wider

Question 14

Where do low frequencies vibrate the basilar membrane?

Answer 14

near the apex- thinner

Question 15

Where are the cilia of the organ of corti embedded?

Answer 15

in the tectorial membrane

Question 16

Where do the cells of the organ of corti sit?

Answer 16

on the basilar membrane

Question 17

Where does the organ of corti synapse?

Answer 17

the spiral ganglion

Question 18

What does force towards kinocilium cause?

Answer 18

opens TRPA1 channel letting K into cell, depolarising

Question 19

What is the function of outer hair cells?

Answer 19

control stiffness, amplify membrane vibration- efferent input

Question 20

What protein in the membrane of outer haircells can change the length of the cell?

Answer 20

prestin

Question 21

What is the response of a outer hair cell to sound?

Answer 21

receptor potenetial and a change in length

Question 22

Why does K travel into the cell in contrast to in otehr parts of the body?

Answer 22

there is a higher K conc. than normal in endolymph so conc. grad inwards

Question 23

What are the 2 mechanisms for frequency coding?

Answer 23

place code ( where on the basilar membrane vibrates); temporal code

Question 24

What is temporal coding in the auditory nerve?

Answer 24

APs are generated at the same frequency as the sound wave

Question 25

How can APs be generated at the same frequncy as sound wave if there is a limit on the number of APs per minute?

Answer 25

summation- all neurons innervating a sinle hair cell code freuqncy together

Question 26

What is the auditory system pathway?

Answer 26

cochlea--cochlear nucleus in medulla--superior olivary nucleus--inferior colliculus--medial geniculate body--audotory cortex

Question 27

What are the 3 different cochlear nuclei in the medulla?

Answer 27

dorsal cochlear nucleus; posteroventral cochlear nucleus; anteroventral cochlear nucleus

Question 28

What is the function of the superior olivary nucleus in the auditory pathway?

Answer 28

locate sound sources in space

Question 29

What is the function of the medial superior olive?

Answer 29

computes sound arrival at the two ears--ipsilateral ear earlier than contraltaeral

Question 30

What part of the vestibular system is responsible for head angular acceleration?

Answer 30

semicircular canals

Question 31

What part of the vestibular system is responsible for head linear acceleration?

Answer 31

saccule and utricle

Question 32

What deforms the hair cells in the labyrinth?

Answer 32

acceleration/gravity

Question 33

What direction of the stereocilia causes depolarisation?

Answer 33

towards the kinocilium

Question 34

What is the crista?

Answer 34

sheet of cells where hair cells are clustered

Question 35

Where do the cilia project into?

Answer 35

cupula

Question 36

What plane is the saccule concerned with?

Answer 36

vertical plane

Question 37

what plane of movement is the utricle concerned with?

Answer 37

horixontal plane

Question 38

Where do the hair cells lie in the otolith organs?

Answer 38

macula

Question 39

What divides the hair cells in the otolith organs?

Answer 39

striola

Question 40

What is the orientation of the hair cell cilia in the otolith organs?

Answer 40

in all directions

Question 41

What are otoconia?

Answer 41

crystals of calcium carbonate that lie on the otolithic membrane-gravity

Question 42

What is the function of the striola of the macula?

Answer 42

allows otolith organs to have multidirectional sensitivity

Question 43

What is the signal of the macular affferents?

Answer 43

tonic, deviations from which are sensitive to acceleration

Question 44

What are the 3 main vestibular reflexes?

Answer 44

vestibulo-ocular reflex; vestibulo-colic reflex and the vestibular-spinal reflex

Question 45

What is the function of the vestibulo-ocular reflex?

Answer 45

keep the eyes still in space when the head moves

Question 46

What is the function of the vestibulo-colic reflex?

Answer 46

keeps the head on a level plane when you walk

Question 47

What is the function of the vestibul-spinal reflex?

Answer 47

adjusts posture for rapid changes in position