VESTIBULAR SYSTEM - MODULE Flashcards
the sensory organs of the vestibular system are located within the…
bony labyrinth
What is the bony labyrinth
an osseous structure found bilaterally in the inner ear within the petrous part of the temporal bone
What are the 3 parts that make up the bony labyrinth
semicircular canals
vestibule
cochlea
What is the membranous labyrinth? what does it contain?
a series of interconnected ducts and sacs that contain the organs of audition and vestibular sense
What are the 3 parts of the membranous labyrinth
semicircular ducts
otolith organs
cochlea
what is the membranous labyrinth filled with
a fluid called endolymph
What are is the membranous labyrinth surrounded by
a fluid called perilymph
Perilymph has HIgh ___ and Low ___
Na +
K+
Endolymph has high ___ and low ___
K+
Na+
What do hair cells do?
transduce mechanical energy into electrical signals
What does each hair cell project
60-100 stereocilia and a single kinocilium
on what side does the hair cell project the stereocilia and kinocilium
on the apical side
the cilia are linked by…
filaments with K+ channels
the depolarizing current in hair cells is triggered by
potassium NOT sodium
why does endolymph have a high [K+]
becase the hair cells are triggered by potassium
What triggers cellular effects in the hair cells
mechanical forces causing the displacement of cilia
what is occuring at the hair cell at rest
- stereocilia parallel to kinocilium
- some K+ and Ca2+ channels open
- Baseline K+ and Ca2+ influx
- baseline glutamate release
- baseline signal
what is the series of events that causes depolarization of the hair cell
- sterocilia move toward kinocilium
- K+ channels open
- K+ influx triggers depolarization
- Depolarization opens voltage-gated Ca2+ channels
- Ca2+ influx triggers glutamate release
- Excitatory signal
what is the series of events resulting in hyperpolarization of the hair cell
- Kinocilium moves toward stereocilia
- K+ channels close
- Very little K+ of Ca2+ influx
- Very little glutamate release
- Very little signal
Vestibular organs send electrical impulses to branches of what cranial nerve
CN VIII the vestibulocochlear nerve
What contain the vestibular organs
the ampulla
Where are the ampulla located
at the terminal end of semicircular canals
What are the haircells sitting in
a gelatinous mass called the cupula
How do the cilia get displaced
when fluid movements within the semicircular duct displace the cupula
The endolymph is displaced ___ relative to the body canal rotating around it
backwards or opposite direction of head and bony canal rotation
for semicircular canals in the same place, head rotations that ___ hair cells in one semicircular canal ____ hair cells in the opposite canal
excite
inhibit
sagittal rotation is what head movement
yes/nod
axial rotation is what head movement
no/shake
coronal rotation is what head movement
maybe
What are the two endolymph-filled sacs in the body vestibules called
the utricle and saccule - the otolith organs
What do the utricle and saccule do
detect linear displacement of the head
Specifically what does the utricle detect
horizontal linear movement - forward and backward acceleration/head tilt
what is the utricle sensory organ called
the macula of utricle
Specifically what does the saccule detect
vertical linear movement - upward and downward acceleration/head tilt
What is the sensory organ of the saccule called
macula of saccule
Across both maculae, hair cells with opposite orientation line up on either side of a central junction called the _____ and are embedded within a ____
Striola
gelatinous otolithic membrane
How do linear head movements activate hair cells
by displacing the otoliths that sit atop the membrane
what are otoliths
calcium carbonate crystals
