Term
| what are the two types of otolith organs? |
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Definition
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Term
| otolith organs encode what stimulus? |
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Definition
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Term
| utricle detects what acceleration? |
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Definition
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Term
| saccule detects what acceleration? |
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Definition
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Term
| the vestibular system does what? |
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Definition
| converts input energy of one form into output energy of another form |
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Term
| what mechanism is used in VS transduction? |
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Definition
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Term
| what two parts is the VS divided into? |
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Definition
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Term
| the peripheral component of the VS includes what? |
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Definition
sensory receptors
8th cranial nerve |
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Term
| what are the sensory receptors of the peripheral VS? |
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Definition
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Term
| what happens after the hair cells are activated? |
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Definition
| causes an AP that is delivered to the 8th cranial nerve and then to the brainstem |
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Term
| where is the vestibular nuclei? |
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Definition
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Term
| what are the three primary roles of the VS? |
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Definition
1) signals position and movement of the head
2) gives a sense of balance
3) coordinates movements of the head and eyes both stationary and moving and facilitates smooth postural transitions |
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Term
| what is the key role of the VS? |
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Definition
| maintain eye stability during positional changes |
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Term
| where are the vestibular receptors located? |
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Definition
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Term
| what are the names of the two types of fluid in the vestibular receptors? |
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Definition
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Term
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Definition
| a potassium rich fluid separating the membranous and bony parts |
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Term
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Definition
| a sodium rich fluid separating the membranous and the bony parts |
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Term
| describe the depolarization during hair cell transduction. |
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Definition
| when the hair cells move toward the kinocilium (longest hair cell in the group) there is a rush of K+ in causing depolarization. The influx of Ca++ into the cell triggers the AP (releasing the neurotransmitter by exocytosis), which goes to the 8th cranial nerve. |
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Term
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Definition
| taller hair cell in the group |
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Term
| when does the AP occur in a hair cell? |
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Definition
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Term
| what happens when the hair cells don't move toward the kinocilium, but in the opposite direction? |
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Definition
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Term
| T/F both sides are active at the same time. |
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Definition
false
when one side is active the other side is quite |
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Term
| otolith organs are receptors that detect what? |
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Definition
| force of gravity and tilts of the head |
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Term
| semicircle canals have receptors that detect what? |
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Definition
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Term
| T/F the vestibular Labyrinth is a set of interconnected structures. |
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Definition
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Term
| the semicircle canals detect what type of acceleration? |
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Definition
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Term
| what is the mechanism the semicircular canals use to create an action potential? |
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Definition
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Term
| how does mechanotransduction work? |
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Definition
fluid moves hair cells->
either hyper polarizes or depolarizes->
AP if depolarization occurs->
exocytosis->
release of the neurotransmitter |
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Term
| T/F the semicircular canals are an open system. |
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Definition
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Term
| where are the hair cells in the semicircular canals? |
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Definition
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Term
| what happens to the fluid if the head is turing the right? |
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Definition
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Term
| in the case of the head moving to the right, what occurs in the left and right VLs? |
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Definition
left-depolarization as the fluid forces the hair cells to the kinocilia
right-hyperpolarization as the fluid moves to the left, forcing the hair cells in the opposite direction of the kinocilia |
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Term
| T/F in the VLs the opposite is always occur with the movement of the head. |
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Definition
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Term
| how are macula oriented in the utricle? |
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Definition
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Term
| how are macula oriented in the saccule? |
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Definition
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Term
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Definition
| basement cells under hair cells that project into a gelatinous membrane with a gelatinous cap with tiny crystals |
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Term
| what is the mechanism to cause an AP that the macula use? |
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Definition
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Term
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Definition
head tilt
acceleration and deceleration |
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Term
| even without head tilt you can sense acceleration and deceleration because? |
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Definition
| the gelatinous membrane on the macula shifts causing the hair cells to shift |
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Term
| explain the central vestibular pathways. |
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Definition
1) the axons of the VL project to the 8th cranial nerve and the vestibular nuclei.
2) the vestibular nuclei in the brainstem, the projects to the cranial nerves that either terminate in the spinal cord or in cranial nerves that cause eye movements. |
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Term
| if the vestibular nuclei project to the spinal cord, what two pathways are used? |
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Definition
lateral vestibulospinal tract
medial vestibulospinal tract |
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Term
where is the lateral vestibulospinal tract located?
what is it in charge of? |
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Definition
located at all levels
innervating all major muscle groups involved in maintain posture |
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Term
where is the medial vestibulospinal tract located?
what is it in charge of? |
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Definition
at cervical levels
innervates in the cervical region, muscles involved with posture |
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Term
| explain the vestibule-ocular reflex. |
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Definition
as the head turns to the right the eyes turn to the left,
innervate muscles that terminate in the eyes because as the head turns, the eyes lag. |
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Term
| why do the eyes lag as the head turns in the vestibulo-ocular reflex? |
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Definition
| to allow for the image to stay on the retina longer and to keep the visual image smoother |
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Term
| damage to the VS can cause what? |
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Definition
difficulty fixating or stabilizing the visual target
create an unstable target |
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Term
| why would damage to the VS cause one to feel like the world is spinning? |
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Definition
medial and lateral vestibulospinal tract
there are multiple things at the same time can mess with physical stability |
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Term
| what does accurate vision require? |
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Definition
| the image remain stable on the retinas even though the head is moving |
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Term
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Definition
| works by sensing rotations of the head then immediately commanding compensatory movement of the eyes in the opposite direction |
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Term
| what is important to note that the VOR is vestibular driven? |
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Definition
it works well in the dark or with they eyes closed
think about driving on a bumpy road, the image remains still because of eye movements to compensate |
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Term
| T/F the vestibular system is an absolute reference system. |
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Definition
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Term
| when did rosenhall find in his cadaver studies? |
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Definition
| that the average number of hair cells of the semicircular canals in individuals was 40% less compared to normal |
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Term
| what was the big message of rosenhall's study? |
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Definition
| decrease in reflexive activity with age |
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Term
| how could you help rehabilitation for someone with loss of balance? |
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Definition
| multiplane rehabilitation to stimulate he VS |
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Term
since the VS is an absolute reference system to other systems what happens with a decline in the system?
what can this cause in older people? |
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Definition
the system reduces the ability to resolve visual and somatosensory conflict (processing visual stimuli in conjunction with somatosensoy input
dizziness |
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