W9 Vestibular system Flashcards
What does the Vestibular system contribute to?
Keepig our eyes still as we move.
Maintaining our upright posture.
Our ability to perceive our own movement within space.
Semicircular canales
3 sets in each ear: horizontal, anterior, posterior
Ampulla
Hair cells
Otolith organs
Detect linear motions, tilting of the head
Utricle and Saccule
Horizontal left to right and back to fowards.
Saccule (ventrical
Vestibular labyrinth is filled with what?
Different chambers filled with endolymph and perilymph.
Endolymph
high extra-cellular potassium concentration.
What is the primary sensory receptors of the vestibular system
Hair cells: respond harder becuase they are all together, better at responding to low frequencies
What do Vestibular hair cells have
hair bundle with stereocilia and tip links.
A kinocilium throughout life
Vestibular hair cells are mechanosensitive.
Same principle as auditory system hair cells.
They respond to lower frequencies (0-20 Hz)
Resting potential, the channels are slightly at rest to enable them to get more negative: hyperpolarize them
What are the two types of vestibular hair cells
Normal type of sensory sysnpas (Type 2)
Type 1: have this long cave, means lots of different synapses can communicate with the long dendrite, found in numerus points.
What does the saccule and the utricle detect?
Head tilt and linear acceleration
Location of hair cells
Sensory patch called macula.
The hair cells don’t have the same direction, they can be activated in diffreent direction.
Gelatinous otolithic membrane:
inside theirs otoconia, respond to gravity because they are heavier.
Why can Vestibular input to the CNS be ambiguous. ?
The membrane moves less quickly than the hair cells. They send exactly the same signals, they need other systems to understand the outputs.
Cupula
Gelatinous structure penetrated by hair bundles.
Cupula is pushed around which moves the hair bundles which send potentials.
The inertia of endolymph during rotation displaces the cupula.
Semicircular canals on either side of the head
Work in pairs.
Horizontal canals on both sides lie in roughly the same plane so can act as a functional pair.
The anterior canal on one side lies in parallel with the posterior canal on the other side so acts as a functional pair.
Why do you feel dizzy when you’ve turned a lot
The endolymph moves the opposite direction than you and moves slower which is why you feel the dizziness after you’ve turned.
Vestibulo-ocular reflex
When you shake your head you vestibular-ocular reflex is quicker.
What does the vestibular nystagmus enable us to do?
It enables the resetting of eye position during sustained head rotation
