Auditory and vestibular system physiology

Question 1

What is the organ of hearing?

Answer 1

Hair cell

Question 2

Which neurotransmitter is involved in the auditory system?

Answer 2

Glutamate

Question 3

Which ion is involved in hair cells?

Answer 3

Potassium

Question 4

Which nerve endings will glutamate act on at the hair cell?

Answer 4

Efferent nerve endings

Question 5

Will sound be amplified or reduced in the middle ear?

Answer 5

Amplified to allow it to travel in the fluid of the inner ear

Question 6

What separates the scala vestibuli from the scala media?

Answer 6

Reissner’s membrane

Question 7

What separates the scala media from the scala tympani?

Answer 7

Basilar membrane

Question 8

Describe transduction in the corti hair cells?

Answer 8

Basilar membrane to tectorial membrane

Question 9

What connects the scala vestibuli and the scala tympani?

Answer 9

Helicotrema

Question 10

What windows does the sv and st connect with respectively?

Answer 10

SV = oval window
ST = round window

Question 11

Where can perilymph be found?

Answer 11

Scala vestibuli

Scala tympani

Question 12

Where can endolymph be found?

Answer 12

Scala media

Question 13

Describe the rigidity of the basilar membrane from the base to the apex?

Answer 13

Rigid at base

Floppy at apex

Question 14

Where will high and low pitched sound be heard within the cochlea?

Answer 14

High = base
Low = apex

Question 15

Where will the rods of corti synapse?

Answer 15

Bipolar neurones with the cell body in the spiral ganglion

Question 16

Will potassium move inwards or outwards in the organ or corti?

Answer 16

Inwards

Question 17

Describe the components of perilymph and endolymph

Answer 17

Perilymph: high sodium, low potassium, glucose of 4
Endolymph: low sodium, high potassium, glucose of 0.5

Question 18

Mutations in what can result in deafness?

Answer 18

Recycling of K+ in the endolymph

Question 19

What will inner hair cells communicate with?

Answer 19

Main source of afferent signal

Question 20

What is the input to outer hair cells?

Answer 20

Efferent inputs from the superior olivary complex

Question 21

What is the function of outer hair cells?

Answer 21

Stiffness

Amplify membrane vibration

Question 22

What protein is present on outer hair cells?

Answer 22

Prestin which can change the length of the cell

Question 23

How does furosemide act in the middle ear?

Answer 23

Inactivates prestin damaging auditory system

Question 24

What will outer hair cells respond to sound with?

Answer 24

Receptor potential

Change in length - movement of tectorial membrane

Question 25

What does tonotopy ensure?

Answer 25

Each neurone innervates several different areas and different neurone types

Question 26

What is tonotopy?

Answer 26

Spatial arrangement of where sounds of different frequencies are processed within the brain

Question 27

What is the function of the medial superior olive?

Answer 27

Computes sound arrival at the 2 ears to generate an interaural time difference using a delay line

Question 28

What is the function of the vestibular system?

Answer 28

Gaze and postural stability Sense of orientation Detection of linear and angular acceleration

Question 29

What part of the vestibular system determines head angular acceleration?

Answer 29

Semicircular canals

Question 30

What part of the vestibular system determines head linear acceleration?

Answer 30

``` Saccule = vertical Utricle = horizontal ```

Question 31

Where can hair cells be found in the semicircular canals?

Answer 31

Crista at the ampulla | They will project into the cupula

Question 32

In semicircular canals are the kinocilium orientated in the same or different direction?

Answer 32

SAME so all excited or inhibited together

Question 33

Are the semicircular canals filled with endolymph or perilymph?

Answer 33

Endolymph

Question 34

Where can otorocnia be found?

Answer 34

Otolithic membrane

Question 35

What is the striola in the macula?

Answer 35

Structural landmark Arranged otoconia into narrow trenches dividing otolith This allows otolith organs to have multidirectional sensitivity

Question 36

What are the 3 main vestibular reflexes?

Answer 36

VOR - eyes still in space as head moves Vestibulo-colic reflex - keeps head still in space when you walk Vestibular-spinal reflex - adjusts posture for rapid changes in position