VESTIBULAR SYSTEM - MODULE Flashcards

1
Q

the sensory organs of the vestibular system are located within the…

A

bony labyrinth

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2
Q

What is the bony labyrinth

A

an osseous structure found bilaterally in the inner ear within the petrous part of the temporal bone

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3
Q

What are the 3 parts that make up the bony labyrinth

A

semicircular canals
vestibule
cochlea

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4
Q

What is the membranous labyrinth? what does it contain?

A

a series of interconnected ducts and sacs that contain the organs of audition and vestibular sense

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5
Q

What are the 3 parts of the membranous labyrinth

A

semicircular ducts
otolith organs
cochlea

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6
Q

what is the membranous labyrinth filled with

A

a fluid called endolymph

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7
Q

What are is the membranous labyrinth surrounded by

A

a fluid called perilymph

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8
Q

Perilymph has HIgh ___ and Low ___

A

Na +

K+

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9
Q

Endolymph has high ___ and low ___

A

K+

Na+

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10
Q

What do hair cells do?

A

transduce mechanical energy into electrical signals

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11
Q

What does each hair cell project

A

60-100 stereocilia and a single kinocilium

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12
Q

on what side does the hair cell project the stereocilia and kinocilium

A

on the apical side

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13
Q

the cilia are linked by…

A

filaments with K+ channels

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14
Q

the depolarizing current in hair cells is triggered by

A

potassium NOT sodium

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15
Q

why does endolymph have a high [K+]

A

becase the hair cells are triggered by potassium

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16
Q

What triggers cellular effects in the hair cells

A

mechanical forces causing the displacement of cilia

17
Q

what is occuring at the hair cell at rest

A
  • stereocilia parallel to kinocilium
  • some K+ and Ca2+ channels open
  • Baseline K+ and Ca2+ influx
  • baseline glutamate release
  • baseline signal
18
Q

what is the series of events that causes depolarization of the hair cell

A
  • sterocilia move toward kinocilium
  • K+ channels open
  • K+ influx triggers depolarization
  • Depolarization opens voltage-gated Ca2+ channels
  • Ca2+ influx triggers glutamate release
  • Excitatory signal
19
Q

what is the series of events resulting in hyperpolarization of the hair cell

A
  • Kinocilium moves toward stereocilia
  • K+ channels close
  • Very little K+ of Ca2+ influx
  • Very little glutamate release
  • Very little signal
20
Q

Vestibular organs send electrical impulses to branches of what cranial nerve

A

CN VIII the vestibulocochlear nerve

21
Q

What contain the vestibular organs

A

the ampulla

22
Q

Where are the ampulla located

A

at the terminal end of semicircular canals

23
Q

What are the haircells sitting in

A

a gelatinous mass called the cupula

24
Q

How do the cilia get displaced

A

when fluid movements within the semicircular duct displace the cupula

25
Q

The endolymph is displaced ___ relative to the body canal rotating around it

A

backwards or opposite direction of head and bony canal rotation

26
Q

for semicircular canals in the same place, head rotations that ___ hair cells in one semicircular canal ____ hair cells in the opposite canal

A

excite

inhibit

27
Q

sagittal rotation is what head movement

A

yes/nod

28
Q

axial rotation is what head movement

A

no/shake

29
Q

coronal rotation is what head movement

A

maybe

30
Q

What are the two endolymph-filled sacs in the body vestibules called

A

the utricle and saccule - the otolith organs

31
Q

What do the utricle and saccule do

A

detect linear displacement of the head

32
Q

Specifically what does the utricle detect

A

horizontal linear movement - forward and backward acceleration/head tilt

33
Q

what is the utricle sensory organ called

A

the macula of utricle

34
Q

Specifically what does the saccule detect

A

vertical linear movement - upward and downward acceleration/head tilt

35
Q

What is the sensory organ of the saccule called

A

macula of saccule

36
Q

Across both maculae, hair cells with opposite orientation line up on either side of a central junction called the _____ and are embedded within a ____

A

Striola

gelatinous otolithic membrane

37
Q

How do linear head movements activate hair cells

A

by displacing the otoliths that sit atop the membrane

38
Q

what are otoliths

A

calcium carbonate crystals