Hearing

Question 1

What is exophthalmia?

Answer 1

Eyes bulging out

Question 2

What are wavelengths/frequency perceived as?

Answer 2

Pitch

Question 3

What is amplitude perceived as?

Answer 3

Loudness

Question 4

What is waveform perceived as?

Answer 4

Tone/timbre

Question 5

What moves the ossicles?

Answer 5

Tympanic membrane

Question 6

What moves the oval window?

Answer 6

Ossicles

Question 7

What transforms the physical motion of the oval window into a neural response?

Answer 7

Cochlea

Question 8

What is the function of the ossicles?

Answer 8

Match impedance of air to impedance of fluid in inner ear

Question 9

How is the pressure increased at the oval window?

Answer 9

Tympanic membrane 20 times larger

Lever action of ossicles

Question 10

By how much is the pressure increased at the oval window compared to the tympanic membrane?

Answer 10

200 times

Question 11

What are the chambers of the cochlea?

Answer 11

Scala vestibuli - superior
Scala media - middle
Scala tympani - inferior

Question 12

Where is the hearing apparatus located in the cochlear chambers?

Answer 12

Between scala media and scala tympani

Question 13

What is the basilar membrane?

Answer 13

Coiled part of cochlea

Question 14

What is the structure of the basilar membrane?

Answer 14

Wider at apex than base

Stiffer at base

Question 15

Which part of the basilar membrane responds to high frequencies?

Answer 15

Base

Question 16

Which part of the basilar membrane responds to low frequencies?

Answer 16

Apex

Question 17

How does the stapes move fluid in the inner ear?

Answer 17

Moves against oval window to move fluid

Question 18

Which cells are the auditory receptors?

Answer 18

Hair cells

Question 19

What is the cell type of hair cells?

Answer 19

Specialised epithelial cells

Question 20

Where are the hair cells located?

Answer 20

Between basilar membrane and reticular lamina

Question 21

How are the hair cells moved?

Answer 21

Pushed and pulled between basilar membrane and reticular lamina

Question 22

What is the function of the organ of Corti?

Answer 22

Where sound waves transduced to neural signals

Question 23

What are the two types of hair cells?

Answer 23

Inner

Outer

Question 24

Which type of hair cell are there more ov?

Answer 24

Outer

Question 25

How many stereocilia does each hair cell have?

Answer 25

100

Question 26

What causes a neuronal signal?

Answer 26

Bending of stereocilia

Question 27

What is the function of stereocilia of outer hair cells?

Answer 27

Amplify sound

Question 28

What is the function of stereocilia of inner hair cells?

Answer 28

Transduce sound to electrical signal

Question 29

What force moves stereocilia?

Answer 29

Shear force

Question 30

What is the status of potassium channels, and thus membrane potential of hair cells?

Answer 30

K channels partially open | Cell partly depolarisd

Question 31

What does deflection of the hair bundle towards the tallest stereocilium cause?

Answer 31

Opening of K channels > more K into cell > depolarisation

Question 32

What does deflection of the hair bundle towards the shortest stereocilium cause?

Answer 32

Closing of K channels > less K into cell > hyperpolarisation

Question 33

What does depolarisation of hair cells cause?

Answer 33

Opening of voltage-gated Ca channels

Question 34

What neurotransmitter is released by the depolarisation of hair cells?

Answer 34

Glutamate

Question 35

Which is larger in hair cells: depolarisation or hyperpolarisation?

Answer 35

Depolarisation

Question 36

What structure recycles potassium in the cochlea?

Answer 36

Vasa vascularis

Question 37

Through what structures does potassium cycle in the cochlea?

Answer 37

Scala tympani > scala media > hair cell > scala tympani

Question 38

What is the proportion of inner hair cell nerves projecting to brainstem nuclei?

Answer 38

95%

Question 39

How do outer hair cells amplify sound?

Answer 39

Amplify movement of basilar membrane because attached to tectorial membrane

Question 40

From which structure do outer hair cells receive efferent input?

Answer 40

Superior olivary complex

Question 41

How do outer hair cells accentuate the movement of the basilar membrane?

Answer 41

Depolarisation > cell contraction | Hyperpolarisation > cell elongation

Question 42

What is the protein in outer hair cells that changes in size depending on membrane potential?

Answer 42

Prestin

Question 43

What is the auditory pathway?

Answer 43

``` Ear - Hair cells - CN VIII - Spiral ganglion Brainstem - Cochlear nucleus in medulla - Superior olive - Lateral lemniscus Midbrain - Inferior colliculus Thalamus - Medial geniculate nucleus Temporal lobe - Auditory cortex ```

Question 44

Where does auditory information decussate?

Answer 44

At cochlear nucleus

Question 45

What mediates sound localisation

Answer 45

Relay nuclei in brainstem

Question 46

What are the parts of the superior olivary complex?

Answer 46

Lateral superior olive Medial superior olive Trapezoid body

Question 47

What is the function of the superior olivary complex?

Answer 47

Localise sound in horizontal domain

Question 48

What does the medial superior olive do?

Answer 48

Localise sound by measuring time delay | - Only for low frequencies

Question 49

What does the lateral superior olive do?

Answer 49

Loalise sound by sensing intensity differences | - Only for high frequencies

Question 50

How is sound localised in the medial superior olive?

Answer 50

Neurons from both ears synapse on same neuron in medial superior olive Time delay between two signals measured

Question 51

How is sound localised in the lateral superior olive?

Answer 51

Head acts like shadow Ear closer to sound hears a greater intensity than ear on other side > lateral superior olive detects difference in excitation from two ears Further inhibition of other lateral superior olive via medial nucleus of trapezoid bodies

Question 52

What is the Brodmann's area of the auditory cortex?

Answer 52

Area 41

Question 53

Where is the auditory cortex?

Answer 53

Herschl's gyrus in temporal lobe

Question 54

How are neurons organised in the auditory cortex?

Answer 54

By frequency - tonotopically organised Alternating regions of input from both ears Core area and belt area around it

Question 55

To which hemisphere are speech sounds lateralised?

Answer 55

Left

Question 56

To which hemisphere are environmental sounds lateralised?

Answer 56

Both

Question 57

To which hemisphere is music lateralised?

Answer 57

Right

Question 58

What does the dorsal pathway encode?

Answer 58

Where

Question 59

What does the ventral pathway encode?

Answer 59

What

Question 60

Where do the dorsal and ventral pathways converge?

Answer 60

Prefrontal cortex

Question 61

What are some peripheral causes of sudden hearing loss?

Answer 61

Meningitis Guillain-Barre Acoustic neuroma Metastasis

Question 62

What is a central cause of sudden hearing loss?

Answer 62

MS

Question 63

What is a cochlear cause of sudden hearing loss?

Answer 63

Infection - HSV - Autoimmune disease - Trauma - Metabolic - Vascular - Ototoxicity