VESTIBULAR SYSTEM Flashcards
Location of vestibular system
inner ear
role of vestibular system
processes sensory information underlying:
Motion
Head position
Spatial orientation relative to gravity
-> responsible for body equilibrium
what does vestibular system use to help body equilibrium
It uses specialized sensory (hair) cells to transduce physical motion into neural impulses.
what happen when the hair (strocillia) move toward kinocillum
depolarization (excitation)
what happen When the hairs (sterocillias) move far from the Kinocillum =
hyperpolarization (inhibition)
explain the depolarization of vestibular hair cells
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).
role of otolith organs
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)
each otolith organs contains
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.
what happen with the otolith organ when the head tilts or move
gravity causes the membrane to shift relative to the macula. The hairs in the gelatinous layer are displaced and a receptor potential is generated.
role of utricle
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.
role of saccule
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.
orientation of hair bundle in utricle
the hair bundles are directed toward the striola, and positioned (more or less) horizontally.
orientation of hair bundle in saccule
the hair bundles are directed away from the striola, and positioned (more or less) vertically.
what is specialized for responding to rotation of the head
semiciruclar canal
role of 3 different semicurcular canal
Horizontal: turning left & right (No sign)
Superior: nodding up & down (Yes sign)
Posterior: tilting to a side (towards the shoulders)
what is the ampula
an enlargement at the base of each semicircular canal. It houses the hair cells.
name of the The hair bundles extend out into a gelatinous mass
cupula
what circulate in the semicircular canal
endolymph fluid
what happen when the head rotated
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.
Each semicircular canal works in _ manner with the partner (pair) located on the other side of the head.
opposite
what happen when the head is tilt to the right side
activates the hair cells in the right horizontal canal but inhibits the hair cells in the left horizontal canal.
The vestibular system contributes to many rapid motor movements such as:
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.
T/F central vestibular processing is multisensory
T because neurons in the vestibular nuclei receive visual, cerebellar and proprioceptive (muscles) inputs.
The vestibular nerve (VIII cranial nerve) projects its fibers to the
vestibular nucleus located in the brainstem. Neurons in the vestibular nucleus send projections to several brain regions
