Lec 20 Flashcards
What planes of movement does the vestibular system sense?
Pitch - sagittal plane
Roll - frontal plane
Yaw - horizontal/transverse
only measures in head, because is close to ears.
describe the nerve that innervates the vestibular system
vestibulocochlear nerve splits into vestibular branch and cochlear branch
vest branch go vestibular system
coch branch go to cochlea
true or false, hair cells are always leaking
what might this do
true - leaking. Afferents fire at 100Hz
Allows for the hyperpolerization of hair cells when kinocilium move towards stereocillia.
What is the long part of the hair cell called, what are the short parts called. what happens when move diff directions.
Long - Kinocilium
short - steriocillia
When steriocillia move towards kinocilium = depolarization and send act pot’s, when move other way, hyperpolarize
where do you find the macula, and the crista
macula (bean) in the saccules (body)
The cristas are found at the …
Describe the canals of the vestibular system.
What is each duct connected to?
What is more proximal to the ducts?
The semicircular canals are bony structures filled with fluid, containing the semicircular ducts inside.
Each duct is connected to an ampulla, which contains a crista (the sensory organ).
Proximal to the ducts is the utricle, followed by the saccule, both containing sensory areas called maculae.
What movement do the cristas detect
the cristas give info about head rotation in each of the planes that aligns with their duct:
- Anterior - detect head nod (sagittal plane)
- posterior - detect lateral flexion (frontal plane)
- Lateral - detect head shake (transverse plane)
what movement do the maculae detect
The maculae give info about linear movement of the head in every direction in the utricle and the saccule
- The utricle detects horizontal movements.
- The saccule detects vertical movements.
- kidney bean (curved) shape of each macula allows for this.
Describe the basic anatomy of crista and function.
The crista is located within the ampulla of each semicircular canal and contains hair cells.
- The cupula, a gelatinous structure, is anchored to the wall of the ampulla and sits above the hair cells.
- Fluid (endolymph) on either side of the cupula moves during head rotation, bending the cupula and influencing the hair cells. Fluid does not pass through the cupula.
- The crista detects rotational (angular) movement of the head in the three axes, corresponding to the three semicircular canals (anterior, posterior, and lateral).
Describe basic anatomy and function of the maculae
Hair cells surrounded in otolithic membrane (jello like), which is topped with otoconia (like sprinkles) that weigh down the otolithic membrane and cause sheering when movement occurs or when tilted.
The maculae contain hair cells embedded in a gelatinous otolithic membrane.
- The membrane is topped with otoconia (calcium carbonate crystals) that add weight.
- When the head tilts or moves linearly, the otoconia cause the membrane to shift (shearing), bending the hair cells’ stereocilia and triggering a sensory response.
- The maculae detect linear acceleration and head tilt (gravity), with the utricle sensing horizontal movement and the saccule sensing vertical movement.
How are the hair cells oriented in the macula of the utricle and the saccule
does this differ from hair cells in the ampullae
utricle - hair cells point towards the striola (in centre
Saccule - hair cells face outwards (away from striola)
In the ampullae, the hair cells point in the same direction
Which way do the hair cells point in relation to the head
if you rotate your head to the right, how wold each
how do they respond to acceleration, deceleration and constant velocity?
the hair cells point so that the kinocilium is behind the stereocillia
if rotate to right, left side increase firing (depolarize), and right side decrease firing (hyperpolarize).
Due to fluid lag behind, once accelerate, get depolarization, once constant they return to normal leakiness.
When decelerate, hyperpolarize (decrease firing).
