Ch 10.2: Vestibular Apparatus & Eq Flashcards
Parts of the VA
1) otolith organs (utricle & saccule) - linear acceleration
2) semicircular canals - rotational acceleration
Inner Ear parts
1) bony labyrinth (surrounding membranous labyrinth)
2) perilymph - fluid (between bony/memb laby)
3) endolymph - fluid in memb laby
Endolymph has an unusually high
[K+] = depolarization ready
What are stereocilia?
modified epithelial cells for sensory reception - not true cilia
kinocilium
true cilia - modified epithelial cells for sensory reception
Stereocilia bending toward kinocilium results in ___
the opening of K+ channels, depolarization, release of NT to depolarize vestibulocochlear nerve
Stereocilia bending away from kinocilium results in ___
hyperpolarization of sensory dendrites
Stereocila and kinocilium system helps to ___
code for detection of direction
Utricle = linear acceleration in the ____ plane
horizontal
saccule = linear accel in the ____ plane
vertical
What houses hair cells?
macula
Where do stereocilia embed?
in the gelatinous otolithic membrane
The otolithic membrane contains ____
stereocilia and crystals of Ca carbonate (otoliths)
At the base of each semicircular canal duct is the
ampulla
Semicircular ducts are filled with
endolymph
Where do hair cells of semicircular canals embed?
in crista ampullaris (stereocilia stuck in gelatinous cupula)
What happens in the semicircular canals when you rotate your head?
endolymph circulates, pushes the cupula to bend the hair cells
Neural Pathways
vestibulocochlear nerve —> vestibular nuclei (medulla & cerebellum) —> oculomotor area of brain stem (controls eye movements) —> down spinal cord (adjust body movements)
When the body is spinning, what happens in the eyes?
eye movements are toward the opposite direction of spin to maintain a fixation point
What happens when the body stops spinning?
the cupula is bent by fluid inertia, with eye movements still affected
Nystagmus
when jerky eye movements produced after spinning
Vertigo
loss of equilibrium from nystagmus
