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Neuro - Physiology > Vestibular Function > Flashcards

Vestibular Function Flashcards

1
Q

where is the vestibular system

A

in the inner ear

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2
Q

the vestibular system has how many semi-circular canals

A

3

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3
Q

what do the semi-circular canals attaach to

A

the utricle

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4
Q

describe the relation of the semi-circular canals to each other

A

they are all at right angles with one another so they can detect motion in 3 directions

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5
Q

the swelling at the base of the semi-circular canal is called the …

A

ampulla

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6
Q

which parts of the vestibular system contain sensory hair cells

A

ampulla, utricle and saccule

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7
Q

what are the otolith organs

A

utricle and saccule

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8
Q

what is detected by the semi-circular canals

A

rotational acceleration

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9
Q

what is detected by the utricle and saccule

A

linear acceleration

utricle: back to front
saccule: vertical

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10
Q

fluid of semi-circular canals

A

endolymph

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11
Q

structure of cristae

A

a cupula in endolymph which has cilia embedded in it

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12
Q

how does the crista detect movement

A

rotation of the head creates inertia which moves the endolymph bending the cupula and the cilia within it in the opposite direction of movement.
sterocilia move in the direction of the kinocilium causing depolarisation and APs sent to the vestibular nerve

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13
Q

two types of cilia in hair cells

A

stereocilia and kinocilium

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14
Q

what happens when stereocilia distort away from the kinocilium

A

hyperpolarisation and decreased in APs to vestibular nerve. tell brain they’re travelling in other direction

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15
Q

origin of vestibulocochlear nerve

A

pons

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16
Q

what happens when travelling in a direction at a constant velocity

A

there is no shearing force on the cilia so no APs sent

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17
Q

what happens when you stop rotation

A

there is shearing of the cupula in the opposite direction

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18
Q

sensory apparatus of utricle and saccule

A

maculae

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19
Q

which direction are the maculae of the saccule orientated

A

on the vertical plane

20
Q

structure of maculae

A

cilia (one kinocilium and many stereocilium) protuding into a gelatinous mass of the otolith membrane. Otoliths (crystals of CaCO3) are embedded in the membrane

21
Q

crystals of what substance are embedded in the otolith membrane

A

CaCO3

22
Q

why are otoliths more affected by gravity than endolymph

A

because they are denser, heavier

23
Q

process of otolith organs detecting movement

A

head tilts –> otoliths follow direction –> distort jelly –> move cilia –> discharge of APs

24
Q

tilting the head back increases/decreases the number of APs sent

A

increases - moves cilia towards the kinocilium

25
Q

tilting the head forwards increases/decreases the number of APs sent

A

decreases

26
Q

which organ detects head movement tilting back and forth

A

utricle

27
Q

where is the vestibular nuclei

A

in the medulla

28
Q

how does info from the vestibular nerve reach the cortex

A

vestibular nerve –> vestibular nuclei –> thalamus –> cortex

29
Q

true/false the vestibular nuclei recieves information from up and down an also sends information up and down

A

true

30
Q

what reflex keep the head in the axis with the body

A

tonic labrinthine reflex (maculae and neck proprioceptors)

31
Q

what reflex makes rapid postural adjustments when falling/tripping

A

dynamic righting reflexes

32
Q

why is balancing harder when you close your eyes

A

because the visual system send descending projections which control posture

33
Q

true/false people with damaged vestibular apparatus can still maintain good balance

A

true - if the movement is slow and the eyes are open. NOT is eyes are CLOSED

34
Q

what is the static reflex

A

when you tilt your head and your eyes intort/extort to compensate so the image stays right way up

35
Q

what is nystagmus

A

involuntary eye movement

36
Q

right nystagmus happens when you rotate _____

A

right (direction of flick back)

37
Q

when your head rotates right which way should your eyes rotate in the orbit

A

left

38
Q

what happens in dynamic vestibular nystagmus

A

the head rotates in a direction and the eyes compensate to stay orientated on the same spot until they reach their limit and flick back

39
Q

what happens in caloric stimulation

A

one ear warm; one ear cold. endolymph is affection by convection
nystagmus occurs in direction of warm ear

40
Q

complications of caloric stimulation nystagmus

A

nausea and vomiting

41
Q

motion sickness happens when which two systems are in conflict

A

visual and vestibular

42
Q

what is overproduced in meniere’s disease

A

endolymph

43
Q

presentation of meniere’s

A

vertigo, nausea, nystagmus, tinnitus

44
Q

what is vertigo

A

feeling of movement when you’re still

45
Q

true/false brainstem lesions can cause nystagmus

A

true

Neuro - Physiology (16 decks)

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