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Vestibular > Part 2 > Flashcards

Part 2 Flashcards

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Preparativo Vestibular e ENEM flashcards
1
Q

who is the judge

A

the vestibular system

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2
Q

can the vestibular system be consciously controlled

A

no

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3
Q

responsibilities of the vestibular system

A

assess movement of the head relative to gravity and the horizon to maintain posture control
stability of images on fovea during head motion
resolves inter-sensory conflicts

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4
Q

components of vestibular system

A

sensorial organs
vestibular nuclei
cerebellum (supervisor)
projections to brainstem, inner ear and cortex

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5
Q

what are the sensorial organs

A

utricle, saccule, Semi-circular canals

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6
Q

what motions of head can vestibular system encode

A

acceleration, decelerations and tilt

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7
Q

why are inner ears the judge

A

because they are internally referenced and don’t rely on the environment to determine since they are incased by bone and only are influenced by gravity

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8
Q

when do the otic placodes develop from germinate epithelium

A

22 days of embryonic life

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9
Q

explain anteroventral part of otocyst development

A

first utricle maculae (week 5E) then Saccule maculae (late week 5E) then cochlear fields are segregated (week 6E)

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10
Q

what are maculae used for?

A

they are used to encode information

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11
Q

what part is developed first vestibular or hearing

A

vestibular

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12
Q

how many sensors are on each ear and explain

A
  1. Each ear has 1 ampullae for each of the 3 SCC, 1 utricle and 1 saccule
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13
Q

how do vestibular hair cells work

A

they convert mechanical displacement into electrical signals which are transmitted by vestibular afferent nerves
50-100 stereocilia and a kinocilium extend into either the otolithic membrane or the cupula
- mechanic deflection opens channels at tip of sterocilia creating depolarizing potential

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14
Q

what are kinocilium

A

tallest filament in bunch
- disappear in hair cells after birth but vestibular hair cells keep them

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15
Q

vestibular hair cells are activated

A

when tip links bend towards kinocilium

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16
Q

vestibular hair cells are inhibited when

A

tip links bend away from kinocilium

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17
Q

Type 1 afferent nerve ending

A

flask shaped (chalice shaped)
1-4 hair cells per nerve ending
irregular afferents: rapid detection of head motion, Vestibular ocular reflex initiation and angular vestibular ocular reflex

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18
Q

Type 2 afferent nerve ending

A

Cylindrical (Button shaped)
- multiple hair cells per nerve ending
regular afferents senstive to a broad spectrum range of motion

19
Q

what is the resting firing rate of type I and II afferent nerve endings

A

70-100 spokes/ second

20
Q

what is the excitation rate of type I and II afferent nerve endings

A

400 spikes/sec

21
Q

what is the inhibition rate of type I and II afferent nerve endings

A

0

22
Q

anatomical components of semi-circular canals

A

filled with endolymph
each has own ampulla (sensor/detector of motion)
ampulla contains crista ampullaris
cupula itself is the gelatinous component of crista ampullaris
- ampulla connects utricle with SCC

23
Q

what are the angular acceleration pairs

A

superior/anterior
posterior/inferior
lateral/horizontal

24
Q

superior/anterior

A

look towards front 45 degrees and highest

25
Q

posterior/inferiror

A

look towards back 45 degrees and lowest (gravity wise)

26
Q

lateral/horizontal

A

almost horizontal 30 degrees

27
Q

what are the vertical canals

A

posterior/ inferior and superior/anterior
- they are perpendicular to each other

28
Q

what canal encodes axial rotation

A

lateral

29
Q

what canal encodes flexsion/extension

A

anterior duct

30
Q

what canal encodes lateral bending

A

posterior duct

31
Q

what direction does fluid move compared to motion

A

opposite direction of motion due to inertia

32
Q

when are hair cells activated

A

when endolymph fluid is in motion

33
Q

location of ampula for anterior scc

A

at front

34
Q

location of ampula for posterior scc

A

back

35
Q

what is crus communae

A

where the anterior SCC canal back and front of posterior SCC are fused together
- open together towards inner ear close to utricle

36
Q

why are static postion changes not encoded by cupula

A

bc cupula spefic gravity is = to endolymph and only acceleration or deceleration is coded
- in gravitational fields not responsive to static postion changes of the head

36
Q

location of ampula for horizontal SCC

A

is at front and opens independently at inner ear
- no crus communae

37
Q

when is motion of liquid (gel) and activation of HC maximal

A

when SCC rotate around perpendicular axis

38
Q

when is motion of liquid (gel) and activation of HC minimal

A

when SCC rotate around longitudinal axis

39
Q

how do we get the perception of head rotation

A

from integrating info from all 6 SCC and nerve centers analyzing activations and inhibitions, encoding head motion in 3 planes of space

40
Q

Edwald’s second law

A

In Horizontal SCC: displacement towards the ampulla= greater VOR response than by acceleration which causes displacement away from ampulla

41
Q

ampullopetal

A

towards ampulla

42
Q

ampullofugal

A

away from ampulla

43
Q

Edwalds third law

A

Vertical SCC: displacement away from ampulla= Greater VOR responses produced than by acceleration which causes displacement towards the ampulla

Vestibular (13 decks)

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