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EXCI 360 > VESTIBULAR SYSTEM > Flashcards

VESTIBULAR SYSTEM Flashcards

1
Q

Location of vestibular system

A

inner ear

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2
Q

role of vestibular system

A

processes sensory information underlying:
Motion
Head position
Spatial orientation relative to gravity
-> responsible for body equilibrium

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3
Q

what does vestibular system use to help body equilibrium

A

It uses specialized sensory (hair) cells to transduce physical motion into neural impulses.

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4
Q

what happen when the hair (strocillia) move toward kinocillum

A

depolarization (excitation)

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5
Q

what happen When the hairs (sterocillias) move far from the Kinocillum =

A

hyperpolarization (inhibition)

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6
Q

explain the depolarization of vestibular hair cells

A

When the hair bundle (sterocillia) is deflected toward the kinocilium, tip links are stretched and directly open cation-selective channels (K+) near the tips of the stereocilia, allowing K+ to flow into the hair cell down their electrochemical gradient (depolarization).

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7
Q

role of otolith organs

A

Detect linear movements:
Translational movements of the head (i.e., forward & backward movements)
Static head position relative to the gravitational axis (i.e., head tilts)

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8
Q

each otolith organs contains

A

Sensory epithelia (macula) consisting of hair cells and supporting cells
Gelatinous layer: hair bundles
Fibrous layer: otolithic membrane
Embedded crystals of calcium carbonate (stones): Otoconia.

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9
Q

what happen with the otolith organ when the head tilts or move

A

gravity causes the membrane to shift relative to the macula. The hairs in the gelatinous layer are displaced and a receptor potential is generated.

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10
Q

role of utricle

A

The utricle (horizontal position) detects the horizontal translational movements of the head (i.e.,moving forward or backward = moving in X axe):
e.g., walking, being in a moving car.

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11
Q

role of saccule

A

The saccule (vertical position) detects the vertical translational movements of the head (i.e.,moving up & down = moving in Z axe):
e.g., being in a moving elevator.

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12
Q

orientation of hair bundle in utricle

A

the hair bundles are directed toward the striola, and positioned (more or less) horizontally.

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13
Q

orientation of hair bundle in saccule

A

the hair bundles are directed away from the striola, and positioned (more or less) vertically.

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14
Q

what is specialized for responding to rotation of the head

A

semiciruclar canal

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15
Q

role of 3 different semicurcular canal

A

Horizontal: turning left & right (No sign)
Superior: nodding up & down (Yes sign)
Posterior: tilting to a side (towards the shoulders)

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16
Q

what is the ampula

A

an enlargement at the base of each semicircular canal. It houses the hair cells.

17
Q

name of the The hair bundles extend out into a gelatinous mass

A

cupula

18
Q

what circulate in the semicircular canal

A

endolymph fluid

19
Q

what happen when the head rotated

A

the movement of the endolymph fluid, which pushes the cupula and displaces the hair bundles in the same direction as the head movement. As a result, the hair cell is depolarized and receptor potential is generated, the electrical signal sent to the brain.

20
Q

Each semicircular canal works in _ manner with the partner (pair) located on the other side of the head.

A

opposite

21
Q

what happen when the head is tilt to the right side

A

activates the hair cells in the right horizontal canal but inhibits the hair cells in the left horizontal canal.

22
Q

The vestibular system contributes to many rapid motor movements such as:

A

Reflexive eye movements that stabilize gaze,
Rapid postural adjustments to maintain balance,
Higher-order processes that are important to our sense of spatial orientation and self-motion.

23
Q

T/F central vestibular processing is multisensory

A

T because neurons in the vestibular nuclei receive visual, cerebellar and proprioceptive (muscles) inputs.

24
Q

The vestibular nerve (VIII cranial nerve) projects its fibers to the

A

vestibular nucleus located in the brainstem. Neurons in the vestibular nucleus send projections to several brain regions

25
Q

The vestibular nerve (VIII cranial nerve) projects its fibers to the

A

vestibular nucleus located in the brainstem. Neurons in the vestibular nucleus send projections to several brain regions

26
Q

vestibular nucleus send projection to which brain region

A

abducens nucleus, thalamus, oculomotor nucleus, cerebellum, spinal cord).

27
Q

VOR produces eye movements that

A

that counter head movements (i.e., moving the eyes in opposing direction to the head), thus permitting the gaze to remain fixed on a particular point:

28
Q

role of vestibulo-cervical

A

VCR regulates head position by reflex activity of neck muscles in response to stimulation of the semicircular canals following a head movement.

29
Q

VCR iniatiate which other reflex

A

the vestibulo-spinal reflex (VSR

30
Q

role of VSR

A

causes the extension of the forelimb and the flexion of the hindlimb, to stabilize the body and protect against a fall.

31
Q

info from otolith organ project mainly to

A

lateral vestibular nucleus

32
Q

Neurons in the vestibular nuclei receive input from

A

the cerebellum, allowing the cerebellum to influence posture and equilibrium (e.g., adjusting VCR & VSR reflex).

33
Q

The vestibular-cerebellar pathways play a critical role in

A

integrating and modulating vestibular signals to:
Enable adaptive changes to the VCR,
Distinguish head tilts from translational movements,
Distinguish passive movements of the head and body from those that are self-generated

34
Q

motion sickness is caused by

A

caused by repeated movements when travelling (e.g., going over bumps). It causes dizziness, nausea, and vomiting.
Explanation: the brain receives conflicting information from the vestibular system, eyes, and muscles nerves. The vestibular system reports rocking back and forth while the car seems perfectly stable based on the visual and somatosensory information.

35
Q

what is oscillopsia

A

A condition in which a person with vestibular damage finds it difficult or impossible to fixate on visual targets while the head is moving (e.g., shooting a target, checking a car’s blind spot…).

The patient has illusion that the environment is moving when his moves his head.

EXCI 360 (14 decks)

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