9-1 Flashcards
Vestibular system function
Provide brain with information about motion, head position, and spatial orientation
What system does the vestibular system work with
Visual
Bodies moving in 3D have —- degrees of freedom
6
Types of degrees of freedom
Translational and rotational
Moving in x, y, and z axis
Translational
Rotational
Roll, pitch, yaw
Pitch
Rotation around y axis
Example of pitch
Chin touching the chest bone and back
Roll
Rotation around the x axis
Example of roll
Ears touching the shoulder
Yaw
Rotational around the z axis
Example of yaw
Chin moving left and right
The labyrinth
Tubes of the vestibular system that form vestibular sensors
Parts of the labyrinth
Otolith organs and semicircular canals
How many semicircular canals are there
3
Otolith organs purpose
Translational movements/acceleration
Otolith organs
Utricle and saccule
Semicircular canals
Rotational movements and accelerations
Ganglion of the vestibular system
Scarpas ganglion
Where are hair cells located
Utricle, saccule, and ampullae
Ampullae
Bulging in semicircular canals
Canal reuniens
Connect cochlea to labyrinth
Vestibular nerve number
VIII
What does the vestibular part join with to form cranial nerve VIII
Auditory part
What are endolymphatic sac and duct responsible for
Regulation of volume and pressure of endolymph, waste removal, and immune response
Ménière’s disease
Endolymph buildup interferes with normal balance and hearing signals between the inner ear and brain (causes vertigo)
What structure comes from the same embroyonic tissue as the labyrinth
Cochlea
What are the cochlea and labyrinth filled with
Endolymph
Purpose of endolymph
Bathes hair cells
What converts gravitational force into action potential
Hair cells
Where do hair cells face in the ampulla
All same direction
Where do hair cells face in the sacculus
Away from each other on opposite sides of the midline
Where do hair cells face in the utricle
Towards each other on opposite sides of the midline
Ampulla movement
Head rotation
Sacculus movement
Translation horizontal
Utricle movement
Translation verticals
Where is the ampulla located
Base of the semicircular canal
Maculae
Sensory epithelium in the utricle and sacculus
When is activated when moving in the z axis
Sacculus and utricle
What is activated when tilting head forward and backwards (x)
Sacculus
What is activated when looking up and down (y)
Utricle
Midline of utricle and sacculus
Striola
Macula
Reticular membrane and supporting cells
What is underneath the supporting cells
Epithelium
Where are the hair cell bodies located
Macula
Where are the stereocilia located
gelatinous layer
What is on top of the gelatinous layer
Otolithic membrane
Otoconia
Ear stones
What happens to the stones when the head is tilted
Stones move towards the direction of the tilt
What happens when the stones move
Stereocilia bend (kinocilia bends in opposite directions on either side)
Sensory epithelium in the utricle and saccule
Macule
When hair cells are depolarized on one side, they are ____ on the other side
Hyperpolarized
Hair cell will ____ when short stereocilia move towards the kinocilia
Depolarize
Hair cell will ____ when kinocilia moves towards the short kinocilia
Hyperpolarize
What happens when the hair cell depolarizes
K+ enters, Ca2+ channels open, AP sent to the brain
Sustained head tilt
Info to the brain will be sustained
No head tilt, transient
Moment when acceleration starts, not sustained. Quickly goes back to normal
Why is there a high basal level of firing
Needs to be able to drop when hyperpolarizing (cant drop below zero)
