The vestibular system

Question 1

What are the 3 semi-circle canals?

Answer 1

Anterior vertical
Posterior vertical
Horizontal

Question 2

Where are hair cells located?

Answer 2

In the ampulla

Question 3

What structure aids with linear movement?

Answer 3

Otolith

Question 4

In which direction does the utricle aid movement with ?

Answer 4

Left
Right
Backwards
Forwards

Question 5

In which direction does the saccule aid movement with?

Answer 5

Up
Down

Question 6

Where are hair cells located?

Answer 6

In the ampulla

Question 7

Why does endolymph have a high potassium conc?

Answer 7

Potential difference provides an electrochemical gradient
- Depolarisation of the hair cells

Question 8

How does depolarisation occur in hair cells?

Answer 8

Due to opening of tip links
- Occurs when taller stereocilia cells pull on tip links
- Opens non-selective cation channels and allow cations to move in
- Causes depolarisation

Question 9

How does hyperpolarisation occur in hair cells?

Answer 9

Tip links push on shorter stereocilia
- Tension on tip links relaxes and channels close
- Leads to hyperpolarisation, more negative membrane potential

Question 10

How are vestibular hair bundles different to auditory hair cells?

Answer 10

The vestibular saccular hair cells keep their kinocilium throughout their life
- Higher resistance due to less flexibility

Question 11

How do type 1 and type 2 vestibular hair cells differ?

Answer 11

Type 1 have a single afference surrounding the base of the vestibular cell
Whereas
Type 2 have vesicles that are released onto afferent dendrites

Question 12

What is the striola?

Answer 12

A line on the utricle which set the polarity of the hair cells
- Hair bundles are arranged in different ways and cause opposite inhibitory and excitatory effects

Question 13

What lies on top of the gelatinous otolithic membrane?

Answer 13

The otoconia calcium carbonate crystals

Question 14

How does the GOM move?

Answer 14

The otoconia calcium carbonate is moved by gravity and causes movement on the GOM
- The hair bundles are pushed and pulled with the GOM

Question 15

How does endolymph protect the vestibular system?

Answer 15

The endolymph moves more slowly than physical structures so buffers the movement

Question 16

How is angular acceleration detected?

Answer 16

The endolymph displaces the cupula
- This orientates the hair cells

Question 17

How do semi-circular canals work in pairs?

Answer 17

An anterior and posterior canal lie in parallel with each other
- One is activated and the other is inhibited
- Functional pair

Question 18

Where is the vestibular nuclei found?

Answer 18

In the medulla

Question 19

Why does the vestibular nuclei interacts with the cerebellum?

Answer 19

Important for balance
- Feeds into spinal cord and cerebral cortex

Question 20

What does interactions between the vestibular nuclei and the reticular formation cause?

Answer 20

Visceral response
-> Ocular motor nuclei inputs into the muscles that control your eyes, aids eye muscle correction

Question 21

Why are you able to move your head and still read?

Answer 21

The vestibular system is faster than the ocular system

Question 22

If endolymph moves to the right, which horizontal canal is activated?

Answer 22

The left horizontal canal

Question 23

What enables the resetting of eye position during a sustained head rotation?

Answer 23

Vestibular nystagmus

Question 24

What is the slow phase of sustained head rotation?

Answer 24

Eyes rotate in the opposite direction to head movement

Question 25

What is the quick phase of sustained head rotation?

Answer 25

Rapid resetting movement back to the centre of the gaze