Term
| vestibular labyrinth and cochlea |
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Definition
organ of balance and organ of hearing
vestibular portion of cranial never VIII, auditory portion of cranial nerve VIII
-membranous sacs within both bony strucutres are filled with ENDOLYMPH=high K+ and low Na+ (similar to cytoplasm |
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Term
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Definition
consists of 2 types of structures: 2 otolith organs, 3 semicircular canals
-each structure has a sensory epithelium containing hair cells, sensory cells for movement |
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Term
| sensory epithelium has polarized organization |
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Definition
-groups of hairs cells have their kinocilia oriented in the same direction
-deflection of cilia towards kinocilium causes depolarization |
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Term
| otolith organs (function, division) |
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Definition
-Function: detects head tilt and linear accelerations
-sensory epithelium=macula
Utricle=macula oriented parallel to the ground, detects motion on horizontal plane
SACCULE=macula oriented perpendicular to ground, detects gravity and vertical fall |
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Term
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Definition
-Function: to detect angular accelerations (rotation)
-sensory epithelium=crista
-has 3 canals (superior, posterior, lateral)
-each canal joins the utricle at an enlargement called the AMPULLA that houses the crista and a gelatinous structure called the cupula |
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Term
| crista orientation in semicircular canals |
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Definition
| in the cirsta, unlike the macula, the kinocilia of ALL the hair cells are oriented in the same direction |
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Term
| signal transduction in hair cells |
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Definition
stretch activated cation channels open when cilia deflected towards kinocilium
1. Ca2+ influz leads to membran depolarization
2. voltage gated Ca2+ channels open
3. neurotransmitter is released to vestibular ganglion cells |
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Term
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Definition
hair cells of macula covered by:
-a gelatinous layer (cilia embedded here)
-otolithic membrane (embedded with otoliths)
-weight of otoliths causes deflection of cilia during movement |
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Term
| push-pull activation of horizontal semicircular canals during head rotation |
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Definition
TURNING LEFT
L canal:
1. increased firing during accell
2. adaptation in firing rate during constant velocity
3.decreased firing during deceleration
R canal=oppposite responses |
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Term
| vestibular axons project to... |
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Definition
-cerebellum
-lateral vestibular nucleus (otolith)
-medial vestibular nucleus (semicircular) |
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Term
| Lateral vestibular nucleus projects to... |
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Definition
| limb motor neurons (maintain posture) |
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Term
| medial vestibular nucleus project to.. |
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Definition
-neck motor neurons (orient head)
-extraocular motor nucleai III, IV, VI |
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Term
| vestibulo-ocular reflex (VOR) |
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Definition
-maintains focus during head motion
-direction of eye movement is opposite the direction of the head turn |
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