vestibular system Flashcards
old dogs can suffer a ____ problem with their vestibular system
temporary
vestibular disease sudden onset of symptoms
twisting and rolling on the ground as if terminally confused; eyes move rapidly back and forth (nystagmus)
the vestibular system
- monitors the position and movement of the head
- gives us our sense of balance and equilibrium
- helps coordinate movements of the head and eyes
- coordinates adjustments to body posture
what happens when the vestibular system is disrupted
- unpleasant, stomach turning feelings we associate with motion sickness (vertigo and vomiting)
- disequilibrium
- uncontrollable eye movements
vestibular labyrinth
within bony labyrinth of inner ear
otolith organs
utricle, saccule
- detect linear acceleration of head
- head tilt
- gravity is a linear acceleration
- otoliths detect tilt of head relative to gravity
3 semicircular canals
- sensitive to head rotation
- angular acceleration of head
these sensory functions are carried out by ____ cells, which communicate with axons of the vestibular portion of the 8th nerve, whose cell bodies lie in ____ ____
hair; scarpa’s ganglion
all bodies moving in three dimensions have six degrees of freedom:
3 translational and 3 rotational
otoliths: utricle and saccule
axes
- detect linear accelerations along the 3 translational axes: x, y, x
- static head tilts relative to direction of the force of gravity
kinocilium
tallest stereocilia
movement of the ____ toward the ____ opens mechanically gated channels and depolarizes it
stereocilia; kinocilium
movement away from the kinocilium ____ the cell
hyperpolarizes
vestibular hair cells are located in the ____ and the ____ and in 3 juglike swellings called ____ in the base of the semicircular canals
utricle; saccule; amupllae
arrows indicate direction of ____ deflection
depolarizing
utricle and saccule detect ____ ____ and ____ ____ of the head induced by tilting or translational movements of the head
static displacements; linear accelerations
what is the macula
the sensory epithelium consisting of hair cells and supporting cells
hair bundles are within a ____ ____ which is covered by ____
gelatinous layer; otoconia
what do otoconia do to the otolithic membrane
make it heavier than fluids around it