In this video I describe the parts of the vestibular system and how they use the movement of fluid to communicate information about balance, movement, and orientation. The vestibular sense also incorporates information from other sensory systems and this can be disrupted by spinning, or in less common situations, by a lack of gravity, both of which can cause nausea and dizziness.
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Vestibular System and Cochlea MRI: https://en.wikipedia.org/wiki/File:Cochlea_and_vestibular_system.gif
Dizzy Sports with Paul Rudd:
https://www.youtube.com/watch?v=Cy0thWiV-eA
For the grammarians, I realize I should have said “nauseated” rather than “nauseous”. Oops!
Video Transcript:
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!
