vestibular system

Question 1

where is the vestibular system located

Answer 1

inner ear

Question 2

what does the vs process sensory info about

Answer 2

motion, head position, spatial orientation relative to gravity

Question 3

the vs is responsible for what and what does it help stabilize

Answer 3

body’s equilibrium and helps stabilize gaze head and posture

Question 4

what does the vs use hair cells to do

Answer 4

transduce physical motion into neural impulses

Question 5

what 2 organs compose the vestibular labyrinth

Answer 5

otolith and semicircular canals

Question 6

what are vestibular hair cells

Answer 6

flask shaped epi cells w a bundle of hair like processes attached btw each other by a tip link

Question 7

whats sterocilia

Answer 7

hair like processes in hair cells

Question 8

what is the name of the longest process in hair cells

Answer 8

kinocillium

Question 9

when the stereocilia moves toward the kinocilium what happens

Answer 9

tip links are stretched and directly open K+ channels near the tips of sterocilia, allowing K+ to flow into hair cell down electrochemical gradient
depolarization (excitation)
the depo of the hair cell opens Ca2+ channels in cell body, allowing Ca2+ entry and release of NT to excite post-synaptic neuron (vestibular n.)

Question 10

when the sterocilia moves away from the kinocilium what happens

Answer 10

hyperpolarization (inhibition)

Question 11

what are the 2 otolith organs and what do they detect

Answer 11

utricle and saccule
linear movements (translational mvt and static head position relative to gravitational axis)

Question 12

what does each otolith organ contain

Answer 12

sensory epi (macula) consisting of hair cells and supporting cells
gelatinous layer; hair bundles
fibrous layer: otolithic mem
embedded crystals of calcium carbonate: otoconia

Question 13

what does otoconia do

Answer 13

makes otolithic mem heavier than the structures and fluids surrounding it

Question 14

what happens after the head tilts or moves to generate a receptor potential

Answer 14

gravirty causes the mem to shift relative to macula, hairs in gelatinous layer are displaced and receptor pot is generated

Question 15

describe utricle (position, what mvt does it detect give an example, where are the hair bundles directed and positioned)

Answer 15

horizontal position
detects horizontal translational mvts of the head
example: moving forward or backwards
hair bundles are towards striola and positioned more or less horizontally

Question 16

describe saccule (position, what mvt does it detect, give an example, where are the hair bundles directed and positioned)

Answer 16

vertical position
detects vertical translational mvts of head
moving up and down
hair bundles are away from striola and more or less positioned vertically

Question 17

what are the semicircular canals responsible for (for each)

Answer 17

responding to rotations of the head
horizontal: turning L and R (no)
sup: nodding up and down (yes)
post: tilting to a side (towards sh)

Question 18

what are ampulla and what do they house

Answer 18

an enlargement at the base of each semicircular canal it houses the hair cells

Question 19

what do the hair bundles extend out into in the semi-circ canals

Answer 19

a gelatinous mass: cupula

Question 20

what circulates in the semi-circ canals

Answer 20

endolymph fluid

Question 21

what happens after endolymph fluid mvt due to rotation of the head

Answer 21

endolymp pushes cupula and displaces hair bundles in same direction as head mvt
which depolarizes hair cell and
generates a receptor potential
electrical signal sent to brain

Question 22

a tilt of the head to R side activates the hair cells in the ___ _____ canal but inhibits the hair cells in the ___ _____ canal

Answer 22

R horizontal
L horizontal

Question 23

what rapid motor movements does the vs contribute to

Answer 23

reflexive eye mvt that stabilize gaze
rapid postural adjustements that maintain balance
higher order processes that are important to our sense of spatial orientation and self motion

Question 24

is the central vestibular processing unisensory or multisensory and why

Answer 24

multisensory bc neurons in vestibular nuclei receive visual, cerebellar and proprioceptive m. inputs

Question 25

the vestibular n. projects its fibers where

Answer 25

vestibular nucleus located in brainstem

Question 26

what is the VOR

Answer 26

vestibuloocular reflex that produces eye mvt that counter head movements to permit the gaze to remain fixed on a particular point

Question 27

what is VCR

Answer 27

vestibulocervical reflex that reg head position by reflex activity of neck m. in response to simulation of the semi-circ canals following head mvt

Question 28

what is VSR

Answer 28

vestibulospinal reflex initiates another reflex the VSR that causes extension of forelimb and flexion of hindlimb to stabilize body and protect against a fall

Question 29

the vestibulocerebellar pathways play a critical role in integrating and modulating vestibular signals to:

Answer 29

enable adaptive changes to the VCR
distinguish head tilts from translational mvt
distinguish passive mvt of the head and body from those that are self-generated

Question 30

why does a person blindfolded on a rotating chair feel that the chair is slowing down and then stoping after 30 s even though its going at a cte velocity

Answer 30

during cte vel, firing rates of vestibular fibers that innervate the semi-circ canals return to baseline levels as the cupula return to its undeflected state

Question 31

why does motion sickness by repeated mvts when travelling cause dizziness, nausea and vomiting

Answer 31

bc the brain receives conflicting info from the vestibular sys, eyes, m. n. the vs reports rocking back and forth while the car seems perfectly stable based on the visual and somatosensory info

Question 32

what is oscillopsia

Answer 32

a person w vestibular damage finds it hard or impossible to fixate on visual targets while the head is moving