The Vestibular System Flashcards
what are the functions of the vestibular system
a) protection from noise
b) development of balance
c) control posture and body movements
d) integrate peripheral sensory information
e) A and C
f) C and D
g) all of the above
C and D)
Control posture and body movements and to integrate peripheral sensory information
transduces head motion into neural information
peripheral vestibular labyrinth
receives, integrates, and distributes vestibular info to control motor activities
central vestibular system
controls eye movements based on head movements
vestibulo-ocular network
coordinates axial musculature and postural reflexes
vestibulospinal network
allows conscious perception of movement and spatial orientation
vestibulo-thalamo-cortical network
three semicircular duct, each with an enlargement (ampulla) near the _________
utricular communication
sensory epithelium in the ampulla is called the __________
crista ampullaris
the crista ampullaris is covered by a gelatinuous mass called the ________
cupula
the cupula is attached at sides and roof to form a fairly effective seal that does not allow ________ to readily flow past it
endolymph
the ______ canal and base of the utricle are tilted upward in the front at an angle of approx. 30 degrees
lateral (horizontal)
what are the two otolith or macular organs?
utricle (horizontal) and saccule (vertical)
the utricle and saccule are housed in the vestibule of the ____________ labyrinth
bony
_____________ is the sensory epithelium in the two otolith structures
macula
each macula is covered by an otolith membrane that has _____________
otoconia (calcium carbonate crystals embedded)
otolith membrane is ________ dense than endolymph.
why?
more; fluid displacement does not move the otolith membrane
________ detect angular acceleration near their plane of orientation
semicircular canals
________ detect linear acceleration in the horizontal place (“roll” or side-to-side head tilt)
utricle
_______ detects linear acceleration in vertical place
(“pitch” or front-to-back head tilt)
saccule
flask shaped
located near central regions of sensory epithelium
ganglion cell terminals form a nerve calyx (covering) at base
Type I
rod shape
located near periphery of sensory epithelium
simple nerve bouton synapses
Type II
Type I and Type II innervations
peripheral process of SGN
efferent fibers from brainstem which control resting & responsive firing rates
depolarization
K+ flow into hair cell, increasing firing rate
hyperpolarziation
results in decrease from resting firing rate
kinocelluar deflection: endolymph movement toward ampulla/kinocilium
depolarization
kinocelluar deflection: endolymph movement away from ampulla/kinocilium
hyperpolarization
firing rate: resting rate (spontaneous)
~90 spikes/sec
firing rate: depolarization rate (excitation)
160-180 spikes/sec
firing rate: hyperpolarization (inhibition)
10-20 spikes/sec
electrical potential is K+ rich ________ at stereocilia versus ________ at lateral and basal regions of vestibular hair cells
endolymph; perilymph
electrical potential
K+ channels opened by stereocilia deflection
hair cell depolarized
voltage-gated Ca+ channels open
increased Ca+ caused neurotransmitter release and afferent fiber response
superior/posterior
push pull pairs
allows the retention of fixed gaze during head movement
vestibulo-ocular reflex
spatial disorientation
dizziness
sensation of movement when no real motion is taking place
vertigo
brief episodic vertigo due to changes in head/body position
- otoconia detaching from curricular macula & entering the semicircular canal system
benign positional vertigo
