Hearing and Balance

Question 1

What are the three parts of the ear

Answer 1

outer ear
middle ear
inner ear

Question 2

What is in the outer ear and what does it do

Answer 2

it contains the external part and ear canal
carries sound waves throughout the ear canal .
external part collects sounds waves and directs them to the tympanic membrane through external auditory canal

Question 3

what is in the middle ear and what does it do

where does it extend from

Answer 3

tympanic membrane and malleus, incus, stapes
Sound waves are conducted through the middle ear
extends from tympanic membrane to oval window. Conducts sound waves over the bones

Question 4

What is in the inner ear and what does it do

Answer 4

cochlear – mechanical vibrations converted into soundwaves

made up of fluid spaces, membrane structures and hair cells - gated ion channels

Question 5

what separates the internal and external ear

Answer 5

tympanic membrane

Question 6

3 fluids in the cochlea

Answer 6

scala vestibuli
scala tympani
scala media

Question 7

Which two fluids contain perilymph> which is like extracellular fluid

Answer 7

scala vestibuli

scale tympani

Question 8

Scala media contains endolymph, what ion is it high in?

Answer 8

potassium so there is an electrochemical gradient between it and the fluid on the outside of the membrane

Question 9

The electrochemical gradient between the endolymph in SM and ICF in what is important for hearing

Answer 9

Hair cells

Question 10

The basilar membrane which is at the base of the organ of corti, which contains sensory receptors, when it moves what does it cause

Answer 10

deplarisation of hair cell in organ of corti

Question 11

what is the function of the tectorial membrane

Answer 11

transforms sounds into mechanical stimuli

Question 12

What are the finger like projections that sit on hair cells in the endolymph between organ of corti and the tympanic membrane

Answer 12

stereocilia

Question 13

Stereocilia are joined by tip links which also attach to what

Answer 13

gated potassium ion channels

Question 14

How is an AP created in hearing

Answer 14

waves of vibration of fluid membranes make hair cells bend causing movement of ions so Ap generated
when stereo cilia move tip links stretch opening potassium channels this opens calcium channels and neurotransmitter released

Question 15

what nerve does the Ap go down

Answer 15

vestibulocochlear nerve

Question 16

How is potassium recycled back into the endolymph

Answer 16

Potassium is recycled back into the endolymph via the stria vascularis

Question 17

High frequency sounds vibrate at start of cochlea and low at the end/apex . What is sound measured in

Answer 17

Decibels – logarithmic scale

10x log10 sound 1/sound 2

Question 18

What is the acoustic reflex- dampen sound

does it fatigue easily after prolonged and sudden noise

Answer 18

Acoustic reflex – stapedius muscle – draws the stapes away form the oval window
contraction in response to loud noise
however fatigues easily and quickly after purloined or sudden noise

Question 19

What is the mechanism of damage from noise

damage to what
what reaction is caused

Answer 19

damage to hair cells/cilia
inflammation
excitotoxicity - neurones damaged by over activation of receptors from excitatory neuroTgltuamate such as NMDA

Question 20

What two ways can hearing be classified as lost

Answer 20

conductive

sensorineural

Question 21

what is conductive hearing loss

Answer 21

outer/middle ear – wax build up/infection

Question 22

what is sensorineural hearing loss

Answer 22

inner ear/brain such as damage to hair cells and nerves

Question 23

what are the two tests to tell type of hearing loss

Answer 23

Rinne test

webers test

Question 24

what is rines test

what instrument is used

Answer 24

acoustic fork – place next to ear and on bone
conductive hearing loss
- - normal – air louder

• • conductive – bone louder
• Sensorineural – air louder

Question 25

What is Webber’s test

Answer 25

middle of forehead
sensorineural deafness - sounds louder on side of intact ear
conductive deafness - sound louder on affected side

Question 26

What test can measure the quality of your hearing

Answer 26

audiogram - I had one

Question 27

In balance there are 3 semi-circular canals what do they do.

what nerve innervates them

Answer 27

Three semi-circular canals – anterior, lateral and posterior

provide senses of balance in all directions.

innervated by the vestibular nerve

Question 28

How Is AP developed in balance

Answer 28

head moves
movement of semicircular canals with basement membrane movement
endolymph causes movement of cupula( hair cells are embedded)
sterocilia bend
tip links stretch
ion channels open
ap in vestibular nerve

Question 29

What are the two eolith organs

Answer 29

utricle and saccule

Question 30

In what lobe is the auditory cortex found

Answer 30

Temporal lobe