Flashcards in Vestibular System Deck (14):
1
3 Kinds of Mechanics
Macromechanics - turning head and making fluid move
Micromechanics - hair cells move
Nanomechanics - molecular gates open
2
3 Semicircular Canals
Lateral for horizontal, and anterior and posterior for vertical
3
Movement Transduction to Hair Cells (3 special terms)
Ampulla is widened section w/ crista coming up (ridge on floor with hair cells). Hairs project into gelatinous cupula. Endolymph movement causes cupula to move, deflecting hair cells
4
Lymph Different Concs
Endo: Low Na/High K
Peri: High Na, Low K like CSF.
Gradient allows hairs to function and depol
5
Alcohol Vestib Effects
Makes cupula less dense than endolymph, leading to stimulation in one direction. Hair cells don't adapt so effects continue until alcohol wears off
6
2 Structural Types of Hair Cells
Type I (Calyx Type) - aff comes in and forms calyx around cell, eff synapses onto calyx
Type II - aff and eff each synapse on hair cell
7
3 Reflexes of Vestibular Signals
Vestibulo-ocular - eyes in head
Vestibulo-collic - head on trunk
Vestibulo-spinal - trunk on ground
8
Vestibulo-ocular Reflex
Turning head right excites R horizontal canal and inhibits L, so R sends excitatory signals to R vestibular nucleus which decussates and excites abducens nucleus, exciting L IV and R III to turn eyes left. L horizontal does opposite everything inhibitorily
9
2 Components of Nystagmus
Slow: Labyrinthine component
Fast: Corrective component, CNS
10
2 Sources of Peripheral Vestibular Hypofunction
Loss of unilateral function (like trauma) loses resting activity of ipsilateral nerve and nuclei and difference is interpreted as motion -> nystagus
Benign paroxysmal positional vertigo (BPPV) means loose ooconia bouncing around, any motion relating to gravity causes nystagmus
11
Caloric Test
Water 7 deg above or below body temp injected into ear, eyes should deviate towards the cold side
12
VCR Test
Vestibulo-collic reflex, play loud noise to stimulate utricle/saccular shit to test otolinth function
13
Meniere's Disease
Endolymph fluid imbalance leads to bulging of membranous labyrinth, causing tinnitus/veritgo/hearing loss. Treat by trying to get water out, maybe gentamicin injections
14