Hi, I'm Michael Corayer and this is Psych Exam Review.
In this video I want to explain a sense that you might not realize that you have. This is your vestibular sense. So I mentioned in the
previous video a part of the inner ear called the vestibular system. This is a crucial part to your vestibular sense. So the vestibular system
helps to coordinate your sense of balance and movement
and it does this very similar to the way that the cochlea works. It does this by using fluid which moves around. So the vestibular system is a
group of structures that are all filled with fluid and when this fluid moves that moves hair cells inside the system
and the movement of those hair cells triggers neurons to fire. Let's take a look at the inner ear. This is the picture we saw in the last video.
The vestibular system is located here just above the cochlea.
We have five main parts to the vestibular system here. Just near the stirrup there there's a section called the saccule, and that just
means "little bag" and it's a little fluid filled bag. Then just above that there's another bag called the utricle
and this comes from the Greek for "little bag", same root as "uterus"
and then we have these three semicircular canals and these are pointed in different directions, they're at 90° angles to one another.
These are also filled with fluid and so when you move your head
the fluid moves in different directions throughout these different canals and that
triggers hair cells and then tells you about which way your head is moving.
So it's a bit hard to see the orientation of these canals in this picture so here's
an MRI
of your vestibular system and also your cochlea. Now you can see these
semicircular canals here that are pointing in different directions.
Here they are here, this would be the cochlea curled up here and the utricle and the saccule would be there and then the auditory nerve
would go off to the brain. OK so that's the vestibular system. But it's important to remember that the vestibular system is just part
of your vestibular sense. It is also incorporating information from other senses, so you also have touch information from your skin, you
have information about your body position, your kinesthetic sense, right? So if you raise your arm that changes all sorts of blood flow
and muscle tension and things like that and you get that information to tell you about your body position in space.
And then you also have your visual system which tells you about which way you're moving and your orientation and so all of these
combine to make your vestibular sense. You can see this if you disrupt the combination of these different
parts. You've probably done this when you were a kid, by spinning around in a circle. So what happens when you do that? You spin
around really quickly and then when you stop you feel dizzy, you feel disoriented. So what's going on?
What's happening is that when you spin around you get the fluid moving in your vestibular system in your inner ear, and then when you
when you stop the fluid has momentum and it continues moving. So now you have this mismatch between the fluid tells you that you're
still moving but your body sense and your visual system tells you that you're not moving
and so you have this disorientation, it's literally this disagreement between these different parts of your vestibular sense. So if you've tried to
play a game like dizzy bat where you spin around and try to do some task hitting a ball are something, you find it's really hard to do.
I put a link in the video description
where you can see some people attempting a number of different
dizzy bat activities. So that's kind of a silly demonstration of this mismatch but it also
has some more serious applications. So pilots have to learn how to deal with this because the
changes that occur in their vestibular system don't always match with other senses. So when they turn, for instance, in a plane
they initially feel this turning movement but then they adjust to this. The plane is
still turning but they may not feel that it's turning.
They call this "the leans". Or when straighten out after a turn
it will feel like they're turning in the opposite direction even though they really aren't.
An even more extreme version of this occurs with astronauts because they experience "space sickness". This is what
happens if you go to an anti-gravity situation or if you just simulate one in something like the "vomit comet" which you may have heard of, a
jet that you descends very rapidly so you feel this sense of weightlessness
this makes people nauseous and they experience this "space sickness".
So the reason for that is that you're disrupting the fluid in the vestibular system, right? There's no gravity holding that fluid in place
keeping its usual patterns of movement. This gets disrupted and it doesn't match with your visual sensations or your body sense
so this can make you very sick. You've probably experienced, it's the same thing that happens if you go on
a roller-coaster and you feel sort of nauseous after.
It's that same disruption of the system, though for astronauts it's more serious and they actually wear patches on their skin
that prevent nausea because you don't want to be vomiting inside of a spacesuit, that would be really terrible.
OK so that's the vestibular system and the vestibular sense overall. I hope you found this helpful
if so, please like the video and subscribe to the channel for more. Thanks for watching!