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Vestibular System
Vestibular System- WUPT
Question | Answer |
---|---|
4 major functions of the vestibular system | Provides: 1.sense of balance 2.information about body position 3.rapid compensatory movements 4.postural reflexes & eye movements |
the two otolith organs | utricle and saccule |
hold receptors for linear accelerations | otholith organs (utricle and saccule) |
holds receptors for rotational accelerations | semi-circular canals |
the ______ labyrinth is filled with endolymph and the ______ labyrinth is filled with perilymph | membranous and osseus |
endolymph is high in ____ and low in ____; while perilymph is high in ___ and low in ___ | K; Na; Na; K |
the location of hair cells in the otolith organs | macula |
location of hair cells in the semicircular canals | ampullae |
tallest stereocilium in hair cell | kinocilium |
movment of the stereocilia towards the kinocilium opens ______ | mechanically gated K channels which cause depolarization and NT release |
movment of the stereocilia away from the kinocilium closes the channels and the cell is | hyperpolarized |
in a given semicircular canal hair cells in ampulla are polarized in the _____ direction | same |
in the otolith organs the _____ divides the hair cells into 2 populations with ____ polarities | striola; opposing |
the hair cells in the sacculus are pointed in a ________ orientation, _____ the striola | verticle; away from |
the hair cells in the utricle are pointed in a _____ orientation, ______ the striola | horizontal; towards |
the right anterior semicircular canal works in conjunction with the _______ | left posterior canal |
the right posterior canal works in conjunction with the _____ | left anterior canal |
the right horizontal canal works in conjunction with the _____ | left horizontal canal |
Overall there are ___ degrees of freedom in the vestibular system | 6; 3 translational and 3 rotational |
within the macula of the otolith organs there is gelatinous layer overlying the hair cells and above this is the ___________ membrane wich is embedded with Ca carbonate crystals called ______ | otolithic; otoconia |
the saccule macula respond to ______, _____ and _____ , ____ movements | up, down and foward, back |
the utricle macula respond to _______ and _________ | head tilts and rapid lateral displacements |
at rest there is a _____ firing rate of the vestibular nerve | constant |
the cupula of the ampula is similar to the _____ of the otolith organs | otolith membrane |
if the head is turned left the hair cells in the left horizontal canal will be ________ and the hair cells of the right horizontal canal will be ____ | depolarized; hyperpolarized |
when the head is at rest the VIII nerves on both sides of the head fire APs at the ____ rate | same |
the function of the _____ is to stabilize your eyes (and gaze) when your head moves | vestibular-ocular reflext |
_____ is much slower than vestibular processing for image stabilization | visual processing |
fast movement that resets the eyes | saccade (named for direction of fast snap) |
right semicircular canal damage will cause a _____ beating nystagmus | left |
in caloric testing a normal response to cold water is ______ and the normal respose to warm water is _____ | saccade to the opposite side; saccade to the same side |
loss of the VOR causes problems with fixation on visual targets while head is moving | oscillopsia |
if you have unilateral damage you ____ recover the ability to fixate; however if you have bilateral damage you _____ | can; cannot (the world will alway seem to be moving) |
the cell bodies of VIII are located in | scarpa's ganglion |
the medial vestibulospinal pathway controls ____ postural reflexes | head |
the lateral vestiublospinal pathway controls ____ postural reflexes | axial and limb (forelimb extension and hindlimb flexion) |
rigid extension of the limbs caused by transection of the brainstem above the level of the vestibular nucleus is called ______ | decerebrate rigidity |
the vestibular axons project to the _____ of the thalamus and then to areas ___ and ___ of the somatosensory cortex | VPL; 3 &5 |
In the sensory organization test patients with a vestibular disorder will do very poorly when _______ | both visual and proprioceptive signals are taken away |