Lecture 17 - The Vestibular System Flashcards
What kind of information does the vestibular system
- Which way is up
- Where you are going
How many receptor organs are in the Vestibular Labyrinth?
Five
What are linear acceleration detected by?
- Utricle
- Saccule
What are angular acceleration measured by?
Semicircular canals
What do certain cells in the epithelium produce?
Endolymph
What is the role for endolymph
Extracellular fluid that bathes the apical surface
- Is rich in K+ but poor in Na+ & Ca2+
What is the structure of Hair cells in the vestibular system?
- Five clusters of hair cells
- Stereocilia at the apical ends
- Kinocilium at one end of the stereoscilia
What is the role the tip link that connects to steroeocilia?
- Connects to an ion channel
- Causes it to open
What do the hair cells act as?
Mechanoelectrical transducers
What happens when the hair bindle deflects towards the kinocilium?
- Causes depolarisation
- Enhances transmitter release
What happens whrn the hair bundle deflects away from the kinocilium?
- Causes hyperpolarisation
- Reduces transmitter release
Where do the hair cells of the vestibular system recieve inputs from?
The brain stem
What is the otolithic membrane?
A sheet that covers the entire macula
The otolithic membrane […] the movement of the head.
Lags behind
What does horizontal acceleration do to the utricle?
- One group of hair cells will activate
- Oppositely oriented hair cells will be suppressed
What direction is the Saccule sensitive to?
Vertical acceleration
What does the gelatinous membrane move relative to?
The underlying epithelium
When does angular acceleration occur?
When an object alters the rate of rotation about an axis
What part of the vestibular system detects angular acceleration?
The three semicircular canals
How do the semicircular canals generate responses?
By using the mass of the endolymph
What is the widest region of the semicircular canal?
The ampulla
What interupts the semicircular canal at its widest part?
The cupula
How are the three semicircular canals arranged?
Perpendicular to one another
What can happen if one of the vestibular labryinths are damaged?
It can cause disorientation and vertigo
What is meniere disease?
- Effects the receptor cells of the vestibular labyrinth
- It is characterised by relapsing vertigo
What causes meniere disease?
May be due to poor drainage of the endolymph
