Chapter 13- Sensory systems (3) Flashcards
The wave peaks at a different part of the basilar membrane depending on what?
Its frequency
What is the basilar membrane like when it is near the stapes?
The BM is smaller and more taut near the stapes (base) so responds to higher frequencies.
What is the basilar membrane like when it is towards the apex?
The BM is wider and looser towards the apex, so responds maximally to lower frequencies.
Semi- circular canals will respond to what?
Angular acceleration
What is the semi circular canals composed of?
Composed of three ducts filled with endolymph
What does each duct in the semi circular canal contain?
Contains hair cells, located in the ampullae.
In the semi circular canal, where is the cilia?
The cilia are embedded in a cap that completely blocks the canal
In the semi circular canal, where are all the kinocillia?
On the side of the cell facing the vestibule.
When the head is still, why are the hair cells not ben t?
Because the endolymph and skull are not moving
When we turn our heads, what will happen?
The endolymph will push against the cupula and bend the hair cells.
The kinocilia in the left semi-circular canal will be bent towards the vestibule (excited)
Those on the right will be bent away from the vestibule (inhibited)
With constant rotation the endolymph will catch up with the bony labyrinth and hair cells will no longer be stimulated.
What does the vestibule do?
Detects angular acceleration.
What is the structure of the vestibule?
Contains two structures called the utricle and saccule.
Within each there is a small area that again contain hair cells.
Within the vestibule, how are the cilia organised?
The cilia are embedded in a dense, stony membrane.
Why does the vestibule conduct inertia?
Because the membrane is so dense
Inertia- the tendency to resist acceleration
Why is the vestibular system important for optometrists?
Because it controls a crucial aspect of eye movements: the vestibulo-ocular reflex (VOR)
This allows a person to keep looking at something when their head moves left or right.
