Auditory System

Question 1

What is sound

Answer 1

The displacement of air particles following a sinusoidal pattern of compression and rerefacation

Question 2

What does a quieter sound wave look like

Answer 2

Shorter amplitude
Longer wave length

Question 3

What does a loud sound wave look like

Answer 3

Higher amplitude
Shorter wave length

Question 4

What does a lower pitch sound wave look like

Answer 4

Lower frequency
Longer wave length

Question 5

What does a higher pitch sound wave look like

Answer 5

Higher frequency
Shorter wave length

Question 6

What is the range of human hearing

Answer 6

20Hz to 20KhZ

Question 7

What are the components of the auditory system

Answer 7

Outer ear- air
Middle ear-air
Inner ear- fluid
Central auditory pathways

Question 8

What makes up the outer ear

Answer 8

Pinna and ear canal

Question 9

What is the pinna

Answer 9

The pinna is the cartillagenous structure on the outside of the ear

Question 10

What is the pinna formed of

Answer 10

It is formed of pharyngeal arches 1 and 2
6x hillocks of His

Question 11

When does the pinna form

Answer 11

Between weeks 10 and 18 weeks in utero

Question 12

What is the function of the pinna

Answer 12

Directed sound waves towards the ear canal

Question 13

What is the ear canal made up of

Answer 13

1/3 cartilage (outer 1/3)
2/3 bone

Question 14

What is the ear drum also known as

Answer 14

Tympanic membrane

Question 15

What is the top 1/3 of the ear drum called

Answer 15

Pars flaccida

Question 16

What are the bottom 2/3 of the ear drum called

Answer 16

Pars tensa

Question 17

What are the bones of the middle ear

Answer 17

Malleus, incus and stapes

Question 18

What are the muscles of the middle ear

Answer 18

Tensor tympani and the stapedius

Question 19

What are the tubes in the middle ear

Answer 19

The Eustachian tube

Question 20

What is the role of the middle ear

Answer 20

Acoustic impedance match between air and fluid filled inner ear
Amplification of the airborne sound vibration which will make it louder

Question 21

How much energy is lost transferring air to fluid

Answer 21

97% loss of energy

Question 22

What is the roles of the muscles of the middle ear

Answer 22

Protection of the inner ear from acoustic trauma
Stiffens the osciular chain
Stapedius is stimulated acoustically
Tensor tympani has voluntary and involuntary control- (chewing)

Question 23

What is the role of the Eustachian tube

Answer 23

Ventilation of the middle ear space
Drainage of secretions

Question 24

What is the inner ear

Answer 24

A set of fluid sacs

Question 25

What is part of the inner ear

Answer 25

Cochlear Labyrinth

Question 26

How is the inner ear innervated

Answer 26

Vestibulochochlear nerve

Question 27

What is the cochlear responsible for

Answer 27

Hearing

Question 28

What is the labyrinth responsible for

Answer 28

Balance

Question 29

What is the cochlea made up of

Answer 29

2.5 turns fluid filled bony tube 3 compartments 2 ionic fluids 2 openings

Question 30

What are the 2 openings in the cochlea

Answer 30

Round window and oval window

Question 31

What are the 3 compartments in the cochlear

Answer 31

Scala tympani Scala media Scala vestibuli

Question 32

What are the 2 cochlear fluids

Answer 32

Endolymph Perilymph

Question 33

How are the gradients of the cochlear fluids maintained

Answer 33

Na, K-ATPase and NKCC1 CIC-K chloride channels

Question 34

What sits on the basilar membrane

Answer 34

The organ of corti

Question 35

What are the hair cells of the organ of corti attached to

Answer 35

Tectorial membrane

Question 36

How are the Scala vestibuli and the Scala tympani connected

Answer 36

The helicotrema

Question 37

What is tonotopy

Answer 37

The basilar membrane responding to different frequency sounds at different points along the membrane

Question 38

Where on the basilar membrane are high frequency sound heard

Answer 38

The base

Question 39

Where on the basilar membrane are low frequencies heard

Answer 39

At the apex

Question 40

How does the organ of corti move

Answer 40

The basilar membrane is a mobile structure which causes the organ of corti to move

Question 41

What is the role of the inner hair cells on the organ of corti

Answer 41

Mechanical transduction

Question 42

What is the role of the outer hair cells of the organ of corti

Answer 42

Fine tuning

Question 43

How are the stereocillia moved

Answer 43

They are moved in a rapid response. They move when the mechanically gated potassium channels open which causes a wave or rapid depolarisation, this causes calcium ions to enter through voltage gated channels. This results in a release of neurotransmitters. Repolarisation then occurs through the influx of potassium ions into perilymph which is low on potassium

Question 44

How is frequency encoded

Answer 44

It is encoded in nerves by location along the basilar membrane

Question 45

How is intensity encoded

Answer 45

Intensity is encoded by numbers responding and by firing rate

Question 46

How is sound transduction encoded

Answer 46

Inner hairs cells

Question 47

How is amplification encoded

Answer 47

Outer hair cells

Question 48

How does sound reach from the ear to the brain to be processed

Answer 48

Via the auditory fibre in the spiral ganglion The spiral ganglion then transmits it via the cochlear nerve (8th nerve) to the central auditory pathway in the brain

Question 49

How is sound localised

Answer 49

Sound is localised by the brain stem

Question 50

What makes up the central auditory pathway

Answer 50

Eighth nerve Cochlear nucleus Olive Lateral leminiscus Inferior colliculus