Vestibular System Flashcards

1
Q

hair cell

A

transducer-do not fire APssynapse with primary afferents

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2
Q

primary afferents

A

-axons in vestibulocochlear nerve-cell bodies in vestibular ganglion (petrous portion of temporal bone)don’t decussate

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3
Q

vestibular system

A

signals posntion and movement-detects acceleration and gravityseries of membranous tubes-in temporal bone

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4
Q

targets of vestibular info

A

cortexcerebellumspinal cord-vestibulospinal tractcranial nerve III, IV, VIreticular formation

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5
Q

hair cell anatomy

A

tallest sterocilia - kinociliumstereocilia on apical surface

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6
Q

apical vs. basilar hair cell

A

endolymph - apical-high Kperilymph - basilar-low K

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7
Q

baseline activity of hair cell

A

results in baseline activity of afferent nerveincrease or decrease firing

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8
Q

kinocilium

A

reference

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9
Q

movement of stereocilia

A

towards kinocilium - depolarizationaway from kinocilium - hyperpolarization

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10
Q

tip links

A

connect stereocilia

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11
Q

peripheral apparatus

A

tubes in temporal bone-nerves through internal acoustic meatussetup orients and applies mechanical force to hair cell stereocilia

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12
Q

ampulla

A

ends of semicircular ductswhere hair cells are

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13
Q

otolith organs

A

where semicircular ducts attachutricle - semicirc duct attachmentsaccule

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14
Q

angular acceleration

A

semicircular ducts

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15
Q

linear acceleration

A

otolth organs

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16
Q

utricle

A

horizontal acceleration

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17
Q

saccule

A

vertical acceleration

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18
Q

fluid lags

A

when head rotation occurs

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19
Q

head rotation

A

tubes rotate-endolymph lags behind-this is detected by hair cells in ampulla

20
Q

functional pairs

A

semicircular ducts function in right/left pairsrespond oppositely in response to head turn-gives differential signal

21
Q

differential signal

A

important because it increases sensitivity of the system-detect minute accelerations

22
Q

otolith organs

A

sense linear acceleration/gravity

23
Q

utricle

A

horizontal

24
Q

saccule

25
maculae
in utricle and saccule-has hair cellscovered by otolith membranes-membrane has greater mass due to ear stones
26
striola
division of maculae-hair cells oppositely polarized in each halforiented in curve
27
each maculae
gives differential signal
28
maculae orientation
every plane in x and y axis
29
peripheral apparatus
include semicircular ducts and otolith organs-detect acceleration and gravity
30
primary efferents
cell bodies in vestibular ganglion
31
axons of primary efferents
vestibulocochlear nervemost synapse in vestibular nuclei-some to cerebellum (ipsilateral)
32
vestibular nuclei
four each side-ventral and lateral to 4th ventricle-distribute info and regulate reflexes
33
vestibular nuclei activity
have baseline
34
targets of vestibular information
cerebellumreticular formationcerebral cortexspinal cortex (LVST/MVST)cranial nerve III, VI, VI-eye movement opposite to keep image on retina
35
vestibuloocular reflex
moving head allows you to focus on moving words-maintain gaze during head movements
36
path of vestibuloocular reflex
axons in MLF - ascend to motor nuclei of III, IV, VI
37
abducent nuclei
cell bodies that are LMNs-ipsilateral lateral rectus m.
38
trochlear nuclei
superior oblique m.
39
oculomotor nuclei
medial rectus, and others
40
nystagmus
series of back and forth eye movements-slow one way, fast other way-can be pathologic of normalslow - VORfast - visual motor systemnamed for direction of fast phase
41
slow nystagmus movement
slow - VOR
42
vestibulocollic reflex
postural muscles of neck-extension ipsilateral to depolarized hair cellsbilateral projectionmedial vestibulospinal tract-descending MLF/MVST
43
vestibulospinal reflex
through lateral vestibulospinal tractipsilateral projectionto LMNs in axial and antigravity muscles of limb
44
vestibular reflexes
based on comparison of differential signalsasymmetry of signals that drives reflexes
45
lesions
irritativedestructive - more common
46
hair cells
can be killed with antibiotices
47
fast phase nystagmus
away from lesionhead/body tilt, leaning and falling toward lesion