The Vestibular System Flashcards
What is the function of the vestibular system?
Generates compensatory responses to head motion
Informs the brain about the position and motion of the head in space
Maintain equilibrium or balance
Keeps eyes fixed on the relevant target when the orientation of the body changes
What responses does the system generate?
Postural responses
Ocular-motor responses
What animal as the most sensitive/ percise vestibulo-occular reflex
Eagle
What are the two receptor system?
Hearing (cochlea) and equilibrioceoption (detecting balance and space orientation)
Located in the inner ear
What does the peripheral vestibular apparatus contain?
3 semicircular ducts found on each side and are perpendicular to each other
A utricle and a saccule (otolith organs)
What is the difference between endolymph and perilymph?
Peri has a decrease of K+ and endolymph has a increase of K+
What happens in the vestibular system during movement?
Membrane potential @ -40 mV and stereovilli and kinocillium are upright
1. When moveing the kino and stero bend towards the kino (causing Ca++ channels to open)
2. -40 mV becomes more positive
3. Ca++ gets released and stimulates vestibular nerve and releases glutamate
4. Nerve goes to vestibular nuclei
5. Synapsing with vestibulospinal ad vestibulocerebellum tracts
how balance is maintained
What happens when the villi don’t bend towards the kinocilium?
Hyperpolarization
K+ leaves
One ear stimulated while the other is inhibited
Angular Acceleration
Endolymph moves forward pushing receptor back and making a deflection
Vestibulo-ocular reflex
- Detection of rotation
- Inhibition of extraocular muscles on one side OR excitation of extraocular muscles on the other side
- Compensating eye movement
Vestibular system effect on neck and limbs
Extensor muscles are contracted on the side where head is accelerating (prevent from falling)
Where does conscious vestibular sensation take place?
Cerebral cortex
What are the general signs of vestibular disease?
Falling, rolling, head tilting, circling, nystagmus, positional strabismus, asymmetric ataxia
