Title: BV4 / Modul 2 / Vestibularis

Q: What is the vestibular system connected to?
A: The vestibular system is connected to the cochlea, the 2 organs come from the same embryonal structure called the otocyst and this is why they are very tightly orginased together

Q: How is the cochlea connected to the vestibulat system?
A: The cochlea is connected to the vestibular system through canal reuniens where the endolymoh is propagating to enrich the fluids of the vestibular system

Q: How many semicircular valves do we have?
A: We have 3 semicircular valves (superior, posterior, horizontal)

Q: Where are the semicircular valves located?
A: All are centralized towards some small organelles called the ampullae where
some of the sentious cells are located

Q: WHich cells are located in the ampullae?
A: Sentious cells

Q: Which parts of the vestibular system are responsible for capturing linear acceleration?
A: The utricle and the sacculus ventriculus that are responsible for capturing  linear accelerations

Q: Which nerves can be found near the vestibular system/cochlea?
A: The audatory nerve and the vstibulsr nerve converge towards the smae area of the cranial nerve VII and we also have part of the facial nerve that also joins quite early on

Q: HOw can the facial nerve affect the inner ear?
A: This is why there is a lot of facial nerve activity that can pollute over the sensory systems here

Q: What does the maculae consist of?
A: - Sacculus
- Utriculus

Q: What can be found in the sacculus and utriculus?
A: Sensory epithelium

Q: How does the sensory epitgelium in the utriculus and sacculus differ from that of the cochlea?
A: The sensory cells have the whole stereocilia structure embedded in a gel, which is here called the otholithic membrane bc on the top of it are crystals called otoliths

Q: What is the sensory epithelium with cyrstals called in the sacculus and utriculus?
A: It's called the
otholithic membrane bc on the top of it are crystals called otoliths

Q: What do we have in the semicircular canals?
A: In the semicircular canals where we have the ampullae we have a different type of structure where we seal so that the sentious cells have the strerocilia embedded in the gelatious struture here its called the cupula and has no otoliths at all

Q: WHat is the sensory epithelium called in the semicircular canals?
A: Cupula - the
sentious cells have the strerocilia embedded in the gelatious struture, here its
called the cupula and has no otoliths at all

Q: How will the cells in the cupula capture the movements?
A: The cupula converts completely towrds the top of the cavity that is there and there these cells will start capturing some of the movements and rotations and this will in turn deflect the stereocilia from the sensory cells, a little bit in the same way that we have in the cochlea

Q: WHich membrane do we have in the utriculus?
A: In the urticulus and the sacculus we have we have this reticular membrane and the cells with the streocilia are protruding into the otolithic membrane

Q: How are the sensory cells oriented on the reticular membrane and what will that result in??
A: The cells are not all oriented in the same matter they are a little bit opposite, so depending on where they are placed and om the epithelium which is not compeletly flat some of the cells will respond to a deflection in a positive direction while other will then be deflected in the other direction, so well get both de- and hyperpolarization and that phenomenon

Q: What does the cells not being oriented the same in the sensory epithelium in theurticulus and sacculus contribute to?
A: Some of the cells will respond to a deflection in a positive direction while other will be deflected in the other direction, so we get both de- and hyperpolarization

Q: How does the otolithic membane function?
A: The way that the otolithic membrane functions is that it will respond to force a little bit such as gravity, so if u have a static tilt and u move ur head backwards this phenomenon where gravity is pulling te otolithic membrane is the same effect as if we have a linear acceleration in a car going forward, so the membrane will be affected in the same way

Q: HOw will the otolithic membrane be affected when one moves ones head forward?
A: If
u move ur head forward that will cause the otolithic membrane to move down and
this phenomoenon will also be related as if u are breaking while u where
having a constant velocity forward and then u stop the car and the
deceletration pulls down the otolithic 
membrane in one direction

Q: What kind of displacement takes place in the utriculus?
A: Linear acceleration in the horizontal plane

Q: What does the nerve activity under the utriculus and sacculus?
A: When u look at the nerve activity underneith the utricle or sacculus that whne u start tilting ur head and once its tilted it's considered a frontward movement and as long as u maintain this, the otolithic membrane maintains the cells in a hyperpolarized manner and this activity will be persisting as long as the head is tilted, as soon as the head goes back the activity of the nerve goes back to normal

Q: WHat happens with the nerve-firing from teh utriculus/sacculus when the head is tilted?
A: If
ur tilt the head in the other direction we will have a change in the charge rate that
will persist as long as the remains tilted and as soon u go back to the normal
condition the activity of the nerve is maintained normal

Q: Which types of rotations can be picked up by the semicircular canals?
A: - Horizontal
- Posterior
- Anterior

Q: What is an ex of a posterior rotation?
A: Hjula

Q: What is an ex of a anterior rotation?
A: Kullerbyttor

Q: Describe the type of rotations the semicircular canals can be captured?
A: If u have movement around ur x-axis (tilt head side to side) u have posterior rotation, u have rotation around ur Z-axis (horizontal canal), backwards or frontwards tilts are the anterior semicircular canals that are responsible for this (y-axis)

Q: How does mechanotransducion differ from that of teh cochlea?
A: Here we have the stereocilia that are captured in hair bundle, within the cupula - the cupula is a gelatinous so when u have the fluids from the endolymph that just bathe the stereocilia with them there - as soon as there is movement in the fluids this is what would cause the cupula to displace itself and this will cahnge the deflection of the stereocilia from these haircells

Q: What causes displacement of teh cupula?
A: As soon as there is movement in the fluids this is what would cause the cupula to displace itself and this will cahnge the deflection of the stereocilia from these haircells

Q: What is causing the movement in the fluid?
A: - It's not the fluids themselves rotating, it's us rotating and the fluid has an inertia - we have rotations of the body but the liquids are still
- So, what is here infact is displacing itself is the cupula - when u move ur head the fluids remain static but u are moving the head and therefore the cupula is getting those movements because they are going against the fluids

Q: What happens when the fluids in the ampullae starts going the same speed?
A: - When the liquids start going at the same speed at that moment we have a constant rotation, since the liquids are going at the same speed as the cupula - there is no more friction and thus the body will be displacing itself at the same speed as the liquids and thus the cupula wouldnt be deflected anymore

Q: What happens with the displacemnet rate when we have an acceleration (rotation)?
A: As soon as we have an acceleration (meaing we have a rotation) we see that we have a change in the discharge rate that then normalizes itself bc once we have maintained constant velocity in that rotation the bundles are no longer displaced

Q: What happens with the charge rate when we have a stop in the rotation?
A: When we have a stop in that a rotation we have a rapid deceleration, we have the change in the charge rate and then its going back to normal

Q: How are right and left vestibular systems going in relation to each other?
A: If u measure left and right vestibular systems they are going in opposite directions bc the way that the cells are arranged are opposite in both systems, one inner ear willl have an increase in the firing and the opposite on ewill have a decrease in the firing

Q: What is teh result of the vestibular systems on eahc side of the head have their cells arranged differently?
A: One inner ear willl have an increase in the firing and the opposite on ewill have a decrease in the firing

Q: What is the vestibulo-ocular reflex?
A: Coordination of head and eye movements

Q: How can the vestibulo-ocular effect be described?
A: When u are stairing at an object ouside when u are on a train - then there will be a rapid movement from the CNS, that brings back the eyes into the original position

Q: How do eye movements move in the vestibulo-ocular reflex?
A: Eye movements counteract head movements

Q: What controls the fast phase in teh vestibulo-ocular reflex?
A: Fast phase - brain control

Q: What controls the slow phase in teh vestibulo-ocular reflex?
A: Slow phase - arcuate effect, this on eis also controlled by the vestibular system

Q: What happens with the eye mucsles at constant rotation?
A: When u have constant rotation u have a connection of the eye muscles to some of the nerves from the vestibular system and these will impair some of the eye movements

Q: How does eye movements work in nystagmus?
A: In nystagmus we have very rapid movement towards the right and slow towards left which is reflecting a rotation on the left
1. n. Abducens is having a positive impact on the exterior muscle on the left eye and a negative on the left one
1. n. Oculomotory nerve have also opposite effects in the middle

Q: HOw is nystagmus typically seen?
A: U can
have sum goggles that are placed over a patient and that pat cannot have a
perfect focus, when u start rotating pat on a chair u can measure the
eyes that are clipping left and right sides,this is where u detect the fast and slow phase depending on the direction
of that rotation,

Q: What can damage in the vestibular system result in?
A: Some
people have damages over their vestibular system, eg if there isnt an
appropriate innervation or if the balance between the 2 isnt maintained in
appropriate desyncrony there will be differences resulting in nystagmus bc
there will be differencies nerve activity bc they are not in equal distribution