Hearing

Question 1

What is the function of the ossicles of the ear?

Answer 1

impedance matching - translate the sound waves in air into sound waves in fluid

Question 2

What are the 3 chambers of the cochlea?

Answer 2

scala vestibuli, scala media, scala tympani

Question 3

What part of the basilar membrane vibrates in response to low frequency sounds?

Answer 3

the apex

Question 4

What cells are responsible for transducing sound into neural signals?

Answer 4

hair cells

Question 5

What causes neuronal signalling for sound?

Answer 5

bending of the stereocilia on the hair cells due to shearing forces from the tectorial membrane

Question 6

Describe the process which leads to neurotransmitter release from hair cells?

Answer 6

when the stereocilia move towards the kinocilium there is complete opening of the potassium channels which results in an influx of potassium and depolarisation, this leads to the opening of voltage sensitive calcium channels which cause a release of glutamate

Question 7

What is the fluid inside the scala media called and what is its potassium concentration?

Answer 7

endolymph - high potassium concentration

Question 8

What is the fluid inside the scala tympani called ad what is its potassium concentration?

Answer 8

perilymph - low potassium concentration

Question 9

What is the role of the outer hair cells?

Answer 9

receive efferent input from the superior olivary complex and change lengths to amplify movements of the basilar membrane (depolarisation causes contraction)

Question 10

How do amino glycoside antibiotics cause hearing loss?

Answer 10

by damaging the outer hair cells

Question 11

Describe the elements of the auditory pathway?

Answer 11

hair cells, auditory nerve, spiral ganglion, cranial nerve, cochlear nucleus in the medulla, superior olive, lateral lemniscus, inferior colliculus in the midbrain, medial geniculate nucleus in the thalamus, auditory cortex in the temporal lobe

Question 12

What area in the brainstem is responsible for integration of information from both ears?

Answer 12

the superior olivary complex

Question 13

Which part of the superior olivary complex is responsible localisation of sound by measuring time delay?

Answer 13

medial superior olives

Question 14

What part of the superior olivary complex is responsible for localisation of sound by sensing intensity differences?

Answer 14

lateral superior olives

Question 15

How do you localise sound for high frequency sounds?

Answer 15

intensity differences

Question 16

How do you localise sound for low frequency sounds?

Answer 16

time delay

Question 17

Where in the temporal lobe is the auditory cortex?

Answer 17

herschls gyrus

Question 18

How are neurons in the temporal lobe organised?

Answer 18

tonotopic organisation

Question 19

Which hemisphere are speech sounds localised to?

Answer 19

left

Question 20

Which hemisphere are music sounds localised to?

Answer 20

right

Question 21

What are some peripheral causes of sudden hearing loss?

Answer 21

meningitis, Guillan-Barre, acoustic neuroma, metastasis

Question 22

What is a central cause of sudden hearing loss?

Answer 22

MS

Question 23

What is a cochlear cause of sudden hearing loss?

Answer 23

infection (HSV), autoimmune disease, traumatic, metabolic, vascular, ototoxicity