Auditory System

Question 1

What do we use sound for?

Answer 1

communication, emotion, survival

Question 2

What does sound cause

Answer 2

one dimensional movement of the two eardrums

Question 3

Sound frequency units

Answer 3

pitch - Hz

Question 4

Sound intensity units

Answer 4

loudness - dB

Question 5

How is sound frequency achieved

Answer 5

cochlear mechanics and physiology of hair cells

Question 6

How is sound intensity achieved

Answer 6

firing rate of many ANFs

Question 7

How is the ear adapted for sound duration

Answer 7

specialised sensory cell synapses for sustaining high rates of neurotransmitter release

Question 8

What features of sound need encoding

Answer 8

frequency, intensity, onset, duration

Question 9

What innervates the cochlear

Answer 9

auditory nerve

Question 10

What lies on the basilar membrane

Answer 10

organ of corti

Question 11

What are the chambers of the cochlea

Answer 11

scala vestibuli, scala media and scala tymphani

Question 12

characteristics of endolymph

Answer 12

high potassium, low calcium

Question 13

Perilymph characteristics

Answer 13

normal

Question 14

Structure of the cochlear

Answer 14

spiral

Question 15

Cells at the top of the cochlear detect

Answer 15

low frequencies

Question 16

What is preserved throughout the auditory pathway

Answer 16

tonotopicity

Question 17

What establishes tonotopicity

Answer 17

basilar membrane travelling wave

Question 18

What are all hair cells defined by?

Answer 18

stereocilia hair bundle and MET channels

Question 19

Where are MET channels located

Answer 19

tips of shorter hair cells

Question 20

How are MET channels opened

Answer 20

force applied to tip links - opens channels

Question 21

What channels are located on the basolateral membrane of general hair cells

Answer 21

voltage gated Ca2+ and voltage gated K+ channels

Question 22

What ion causes the inward resting transducer current

Answer 22

potassium

Question 23

What is surrounded by endolymph?

Answer 23

apical surface of hair cells and stereocilia

Question 24

True or False - endolymph and perilymph mix

Answer 24

false

Question 25

Effect of large movement/deflection of hair bundle on cell

Answer 25

channels open, large transducer current depolarises the cell

Question 26

Excitatory deflection of hair bundle on APs

Answer 26

rapid train of action potentials

Question 27

MET current during inhibitory deflection

Answer 27

NO MET current

Question 28

Transducer channels closed causes

Answer 28

hyperpolarisation

Question 29

Inner hair cells

Answer 29

primary sensory receptors of mammalian cochlear

Question 30

Difference between IHC and general hair cell

Answer 30

number of different potassium channels on cell membrane

Question 31

Membrane potential oscillations

Answer 31

MP oscillates between depolarisation and hyperpolarisation at the same frequency as sound

Question 32

Inner hair cell hair bundle deflect effect

Answer 32

hair cell depolarises and nerve activity increases

Question 33

When do oscillations saturate

Answer 33

2/3 kHz

Question 34

How does the cell respond to sound frequencies above 2/3 kHz

Answer 34

sustained graded receptor potential

Question 35

What is the function of OHCs

Answer 35

cochlear amplifier

Question 36

What is present on OHCs cell membrane

Answer 36

prestin

Question 37

Prestin function

Answer 37

allows cells to contract in response to changes in MP

Question 38

Efferent fibres effect on OHCs

Answer 38

inhibitory - turn OHCs off

Question 39

What are efferent fibres associated with

Answer 39

post-synaptic cisterns

Question 40

Resting transducer current is larger in

Answer 40

OHCs

Question 41

Effect of sound on OHCs

Answer 41

cell shortens and elongates

Question 42

Depolarisation effect on OHCs

Answer 42

shortens

Question 43

Function of OHCs up and down movement

Answer 43

positive feedback, increases movement of basilar membrane, to increase IHC stimulation

Question 44

Which afferent neurons in the cochlear are resilient to nerve damage

Answer 44

type 1 SGNs

Question 45

What do type 1 SGNs innervate

Answer 45

IHCs

Question 46

Function of type 1 SGNs

Answer 46

carry all sound information from IHCs to cochlear nucleus

Question 47

What do type 2 SGNs innvervate

Answer 47

OHCs

Question 48

Function of Type 2 SGNs

Answer 48

not known, thought to be related to nociception in cochlear

Question 49

Characteristics of type 2 SGNs

Answer 49

branched, synapse in cochlear nucleus

Question 50

Sound information transport

Answer 50

carried to brain via type 1 SGNs, type 1 SGNs contact IHCs and type 2 SGNs contact OHCs