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Cognition & Senses - wk 2 > vestibular system > Flashcards

vestibular system Flashcards

1
Q

old dogs can suffer a ____ problem with their vestibular system

A

temporary

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2
Q

vestibular disease sudden onset of symptoms

A

twisting and rolling on the ground as if terminally confused; eyes move rapidly back and forth (nystagmus)

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3
Q

the vestibular system

A
  • monitors the position and movement of the head
  • gives us our sense of balance and equilibrium
  • helps coordinate movements of the head and eyes
  • coordinates adjustments to body posture
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4
Q

what happens when the vestibular system is disrupted

A
  • unpleasant, stomach turning feelings we associate with motion sickness (vertigo and vomiting)
  • disequilibrium
  • uncontrollable eye movements
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5
Q

vestibular labyrinth

A

within bony labyrinth of inner ear

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6
Q

otolith organs

A

utricle, saccule

  • detect linear acceleration of head
  • head tilt
  • gravity is a linear acceleration
  • otoliths detect tilt of head relative to gravity
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7
Q

3 semicircular canals

A
  • sensitive to head rotation
  • angular acceleration of head
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8
Q

these sensory functions are carried out by ____ cells, which communicate with axons of the vestibular portion of the 8th nerve, whose cell bodies lie in ____ ____

A

hair; scarpa’s ganglion

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9
Q

all bodies moving in three dimensions have six degrees of freedom:

A

3 translational and 3 rotational

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10
Q

otoliths: utricle and saccule

axes

A
  • detect linear accelerations along the 3 translational axes: x, y, x
  • static head tilts relative to direction of the force of gravity
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11
Q

kinocilium

A

tallest stereocilia

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12
Q

movement of the ____ toward the ____ opens mechanically gated channels and depolarizes it

A

stereocilia; kinocilium

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13
Q

movement away from the kinocilium ____ the cell

A

hyperpolarizes

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14
Q

vestibular hair cells are located in the ____ and the ____ and in 3 juglike swellings called ____ in the base of the semicircular canals

A

utricle; saccule; amupllae

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15
Q

arrows indicate direction of ____ deflection

A

depolarizing

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16
Q

utricle and saccule detect ____ ____ and ____ ____ of the head induced by tilting or translational movements of the head

A

static displacements; linear accelerations

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17
Q

what is the macula

A

the sensory epithelium consisting of hair cells and supporting cells

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18
Q

hair bundles are within a ____ ____ which is covered by ____

A

gelatinous layer; otoconia

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19
Q

what do otoconia do to the otolithic membrane

A

make it heavier than fluids around it

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20
Q

when head tilts gravity causes ____ ____ to shift relative to sensory epitheloum

A

otolithic membrane

21
Q

what does shearing cause

A

displacement of hair cell bundles and a receptor potential in hair cell

22
Q

during linear accelerations of the head there is also a “shearing” motion betwen the ____ ____ and the ____ ____

A

sensory epithelium; otolithic membrane

23
Q

the greater mass of the ____ ____ causes it to temporarily lag behind the ____ ____, leading to transient displacement of hair cell bundle

A

otolithic membrane; sensory epithelium

24
Q

hair cell response is

linear acceleration

A

transient

25
Q

during static tilt hair cell response is

A

sustained

constant acceleration due to gravity

26
Q

what type of response is of the vestibular nerve axon from an otolith organ to forward and backward changes in head tilt

A

sustained response

27
Q

what type of response is of the vestibular nerve axon from an otolith organ to forward and backward acceleration of the head

A

transient response

28
Q

hair cells on opposite sides of the ____ have opposing directional polarities

A

striola

29
Q

what organs are responsive to head displacements on all directions

A

otolithic

30
Q

utricle is mainly concerned with motion in the ____ plane

A

horizontal

31
Q

saccule mainly concerned with motion in the ____ plane

A

vertical

32
Q

at the base of each semicircular canal is a bulbous expansion called the

A

ampulla

33
Q

within the ampulla is the sensory epitheloum called the ____ that contains the hair cells

A

crista

34
Q

the hair bundles of the ampulla extend into a gelatinous mass called the

A

cupula

35
Q

how is the cupula distorted by movements of the endolymphatic fluid

A

when the head turns in the plane of one of the semicircular canals, the inertia of the endolymph produces a force across the cupula, moving it away from the direction of head movement and causing displacement of the hair bulbs

36
Q

when cupula moves in the appropriate direction, all the hair cells are

A

depolarized

37
Q

when the cupula moves in the opposite direction all the hair cells are

A

hyperpolarized

38
Q

head rotation moves the cupula in opposite directions for the two partners, resulting in:

A

opposite changes in their firing rates

39
Q

what is angular acceleration

A

transient response of vestibular nerve axon from left and right horizontal semicirculat canals to left rotation of the head

40
Q

hair cells in the left horizontal canal ____ when the head turns left

A

depolarize

41
Q

hair cells in the right horizontal canal ____ when the head turns left

A

hyperpolarize

42
Q

what are the 3 reflexes of central pathways for stabilizing gaze, head and posture

A
  • maintain equilibrium and gaze during movement
  • maintain posture and balance
  • maintain mucle tone
43
Q

lateral vestibulospinal tract

A
  • ipsilateral forelimb and hindlimb extensors
  • balance
44
Q

medial vestibulospinal tract

A

bilateral to motor neurons for neck

45
Q

vestibulo-ocular reflex (VOR)

A

head rotation activates semicircular canals in inner ear and drives compensatory eye movements to stabilize image of visual world on the retina

46
Q

optokinetic nystagmus

A

induced by looking at moving visual stimuli, such as moving horizontal or vertical lines, and/or sripes

47
Q

postrotatory nystagmus

A

if one spins in a chair continuously and stops suddently, the fast phase of nystagmus is in the opposite direction of rotation, known as the “post-rotatory nystagmus”, while slow phase in in the direction of rotation

48
Q

pathologic nystagmus

A

damage to one or more components of the vestibular system - labyrinthitis or vestibulitis or vestibular disease

Cognition & Senses - wk 2 (5 decks)

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