vestibular function

Question 1

what reflex maintains normal head position?

Answer 1

vestibulo-colic reflex (VCR)

- controls neck muscles and posture

Question 2

what reflex keeps eyes focused on the target?

Answer 2

vestibulo-ocular reflex (VOR)

-controls ocular muscles

Question 3

what are the 5 organs in the vestibular labyrinth?

Answer 3

1. saccule
2. utricle
3. anterior SCC
4. lateral SCC
5. posterior SCC

Question 4

what are the otolith organs and what do they do?

Answer 4

saccule and utricle

- sensors for linear motion

Question 5

what is the function of the semicircular canals?

Answer 5

sensors for rotational motion

Question 6

what is the non-sensory organ in the vestibular labyrinth?

Answer 6

endolymphatic sac

Question 7

what is the sensory organ for hearing?

Answer 7

cochlea

Question 8

what kind of sensors are hair cells?

Answer 8

mechanosensors

Question 9

hair cells in the cristea reach into what?

Answer 9

cupulla

Question 10

hair cells in the maculae reach into what?

Answer 10

otoconia-membrane

Question 11

otoconia-membrane is a glyco-protein maxtrix with what?

Answer 11

CaHCO3 crystals (=HEAVY!)

Question 12

endolymph is a ___ solution that is secreted by ___?

Answer 12

• KCL

- vestibular dark cells (VDC)

Question 13

perilymph is a ___ solution

Answer 13

NaCl

Question 14

how is the stimulus in vestibular hair cells coded?

Answer 14

graded DIFFERENCE in frequency

Question 15

do you need both sides of the head to detect movement?

Answer 15

yes

Question 16

what senses linear motion in the Z direction?

Answer 16

saccule

Question 17

what sense linear motion in the XY plane?

Answer 17

utricle

Question 18

what is the sensation you get in an elevator detected by?

Answer 18

saccule

Question 19

What does VCR control?

Answer 19

1. integration sensory input
2. control of neck muscles
3. control posture and gait

Question 20

what does VOR control?

Answer 20

1. integration of sensory input
2. control of ocular motion
   - maintaining a stable image on the retina
   - required for clear vision

Question 21

why does dizziness happen?

Answer 21

the endolymph starts moving and you are dizzy afterward because they fluid is still moving when you stop

Question 22

continuous turning leads to fast reset motions of the eyeball - called what

Answer 22

nystagmus

Question 23

if you are rotating to the right, which way will the nystagmus be during the rotation?

Answer 23

to the right

Question 24

if you are rotating to the right for a period of time and then stop suddenly, what direction will the nystagmus beat?

Answer 24

to the left

Question 25

if there is fresh damage to the left side, and the eyes wander to the left, which direction will nystagmus beat?

Answer 25

to the right (the healthy side)

Question 26

what is the term for perception that the world if spinning?

Answer 26

vertigo