Chapter 11 - Vestibular

Question 1

What are the otolithic organs? What do they detect?

Answer 1

• utricle, saccule
• detect linear acceleration of head and Head tilt: gravity is a linear accelerator —> otoliths detect tilt of head relative to gravity

Question 2

What do semicircular canals detect?

Answer 2

Angular acceleration of head and head rotation

Question 3

How does vestibular hair cell transduction work?

Answer 3

Movement of Stereocilia toward the kinocilium opens mechanically gated channels and depolarized cell

Question 4

Where are vestibular hair cells located?

Answer 4

In the utricle and the saccule and in three jug like swellings called ampullae in the base of the semicircular canals

Question 5

What is the composition of the otolithic membrane?

Answer 5

Otoconia and hair bundles located in a gelatinous layer

Question 6

What is the macula? What is its composition?

Answer 6

Sensory epithelium. Consists of hair cells and supporting cells

Question 7

Explain the shearing motion

Answer 7

Otolithic membrane is heavier than fluids around it. Therefore there is a shearing motion which causes displacement of hair cell bundles and a potential in hair cell

Question 8

Explain what happens between the otolithic membrane and the sensory epithelium during linear acceleration

Answer 8

Also a shearing motion due to the greater mass of the otolithic membrane. This causes it to temporarily lag behind sensory epithelium leading to transient displacement of hair cell bundle

Question 9

What can you say about hair cells on opposite sides of the striola?

Answer 9

They have opposing directional polarities

Question 10

What are the utricle and saccule mainly concerned with respectively?

Answer 10

Utricle: motion in horizontal plane
Saccule: motion in vertical plane

Question 11

What is at the base of each semicircular canal?

Answer 11

Ampulla

Question 12

WhAt is the composition of the ampulla?

Answer 12

The sensory epithelium called the crista that contains hair cells

Question 13

What do you call the gelatinous mass into which the hair bundles extend?

Answer 13

Cupula

Question 14

what happens to the cupula during angular acceleration?

Answer 14

It is distorted by endolymphatic fluid. The inertia of the endolymph produces a force across the cupula moving it away from the direction of head movement causing displacement of hair bundles