Physiology: Auditory, Vestibular and Visual Systems

Question 1

role of the hair cells?

Answer 1

transduces vibratons to sound

Question 2

transmitter in the auditory system

Answer 2

glutamate

Question 3

three fluid-filled cavities in the cochlea

Answer 3

1. scala tympani
2. scala vestibuli
3. scala media

Question 4

what forms the perilymph?

Answer 4

scala tympani and vestibuli

Question 5

what connects the scala tympani and vestibuli?

Answer 5

helicotrema

Question 6

what does the scala tympani meet from the middle ear?

Answer 6

oval window

Question 7

what does the scala vestibuli meet from the middle ear?

Answer 7

round window

Question 8

what does Reissner’s membrane separate?

Answer 8

separates scala vestibuli and scala media

Question 9

what does the basilar membrane separate?

Answer 9

separates scala media and scala tympani

Question 10

where are the hair cells located?

Answer 10

they have stereocilia located on the basilar membrane with tips in the tectorial membrane

Question 11

what happens to the tectorial membrane?

Answer 11

it vibrates causing the cilia to bend and hair cells release neurotransmitters which synapse on bipolar neurones with cell bodies in the spiral ganglion

Question 12

role of the protein prestin

Answer 12

changes space between basilar membrane and tectorial membrane

Question 13

what can furosemide inactivate?

Answer 13

the protein prestin and so can cause hearing loss

Question 14

hair cells electrochemical current

Answer 14

K+ is inwards so the endolymph has a high concentration of K+ causing it to move to hair cells

Question 15

what does the medial superior olivary nucleus do?

Answer 15

detects time interval between sound arriving at each ear

Question 16

what does the lateral superior olive do?

Answer 16

difference in sound intensity between ears

Question 17

what does the vestibular system do?

Answer 17

provides information about gravity, rotation and acceleration

Question 18

role of the semi-circular canals?

Answer 18

detect head movement

Question 19

what are the semi-circular canals?

Answer 19

3 fluid-filled (endolymph) canals at right angles to each other

Question 20

structure of the semi-circular canals

Answer 20

contain endolymph

contain an ampulla that contains crista (hair cells)

Question 21

what plane does the posterior canal share?

Answer 21

contralateral anterior canal

Question 22

what are the otolith organs?

Answer 22

saccule and utricle

Question 23

what do the otolith organs sense?

Answer 23

linear acceleration and gravity

Question 24

where are hair cells located in the otolith organs?

Answer 24

lie in the macula and are divided by striola

crystals of calcium carbonate are called otoconia

Question 25

three major vestibular reflexes

Answer 25

1. vestibulo-ocular reflex
2. vestibulo-colic reflex
3. vestibular-spinal reflex

Question 26

role of the vestibulo-ocular reflex?

Answer 26

keep eyes still in space when head moves

Question 27

role of the vestibulo-colic reflex

Answer 27

keeps head still in space when you walk

Question 28

role of the vestibular-spinal reflex

Answer 28

adjusts posture for rapid changes in position

Question 29

dark current

Answer 29

constant influx of Na+, positive depolarising current causing a steady release of neurotransmiter

Question 30

what happens to the dark current when exposed to light?

Answer 30

Na+ is reduced and efflux of K+ causes hyperpolarisation

Question 31

role of centre-surround organisation/ lateral inhibition

Answer 31

enhances areas of difference/ contrast