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  • I've got a little challenge for you this week. If you're able to, stand on one foot

  • with your hands on your hips for 30 seconds. Keep your feet and hands as still as possible.

  • If your hands lift off your hips, you lose a point. If your toes come off the ground,

  • you lose a point. If that's too easy, close your eyes. That should've made it harder,

  • but not impossible. With your eyes still closed, put your hands

  • hands over your ears. That should've made it harder, but why?

  • Yes, you changed your balance point to be more top heavy, but you also changed

  • one of your primary ways of establishing balanceyour ears. While balancing on one foot

  • makes for a fun little challenge, this phenomenon also explains the sensation of vertigo. So

  • in this video, we'll go over the delicate anatomy that gives us our sense of balance.

  • To understand how our ears influence balance, we'll need some background anatomy. Anatomists

  • typically divide the ear into three main sections: the outer, middle, and inner ear. The outer

  • ear includes everything you see on the surface plus the ear canalmostly elastic cartilage

  • wrapped in skin that's rich with sebaceous oil glands and ear wax glands. At this point,

  • the purpose of the ear is just to collect sound waves, kind of like how a satellite

  • dish is concave to collect radio wavesThose sound waves rattle the eardrum, or tympanic

  • membrane, an extremely thin membrane that amplifies and transmits sound waves to the

  • three smallest bones in our bodiesthe hammer, anvil, and stirrup or malleus, incus,

  • and stapes if you want to use Latin. Then those vibrations wiggle the cochlea in the

  • inner ear, which transforms vibrations into nervous impulses that travel to the brain

  • and get interpreted as your favorite Tiktok song. This is my how do you do, fellow kids

  • moment isn't it? Right next to the cochlea is the tiny vestibular system, which includes

  • three semicircular canals, and tiny segments called the utricle and saccule, all of which

  • are filled with fluid. These things are the main organs for balance. If we shrunk down

  • into the semicircular canals, we'd find a space lined with little sensory cells called

  • hair cells, named so because they poke out of the canal a little bitnot because

  • they're actual hair. Whenever we turn or tilt our heads, the inner ear moves with it,

  • and the fluid inside the canals sloshes back and forth. And that movement of the fluid

  • pushes on the hair cells, which are sensitive enough to detect less than a nanometer's

  • length worth of movement. Each of those canals detects motion on a different axisone

  • detects tilting up or down, one detects rotation, and one detects bending left or right. The

  • other organs, the utricle and saccule, works similarly. They both have those hair cells,

  • but they have tiny calcium crystals on them. That makes this part of the balance organ

  • specialized to detect acceleration. I personally picture the balance organs like those spirit

  • levels with the bubbles inside them. But instead of our eyes determining the position of the

  • bubble visually, the sensors are built into the level. From there, the balance organs

  • work like any other sense. They convert the motion from the hair cells into nervous impulses

  • and send them to the brain. There, they combine with information like what your eyes are focusing

  • on, or the position of your foot, or the stretch of certain tendons. But every now

  • and then, those different inputs conflict with each other like when you're on a boat

  • or airplane, which manifests as dizziness or even nausea. Unfortunately, all of these

  • sensory systems break down as you get older. So it's no surprise that the elderly are

  • at a drastically increased risk of experiencing dizziness and falls over their younger selves.

  • While just about every part of your balance organs deteriorates over time, you start losing

  • hair cells as you age which contributes to impaired balance. But even before you start

  • aging, if you have a disease or injury that affects the inner ear, there's a good chance

  • it'll throw off your balance. The most common cause of vertigo in adults is called benign

  • paroxysmal positional vertigo, or BPPV, and it happens when some of the crystals in the

  • inner ear become dislodged from where they usually are. Or there's Meniere's disease

  • which is an inner ear disorder that might be caused by abnormal buildup of fluid in

  • the balance organsscientists aren't totally sure why it happens. This causes vertigo

  • and ringing in the ears, although typically just one ear. So it's a bit of a tradeoff.

  • We have this intricate, three dimensional system for detecting our position in space,

  • but it's delicate. I wish I could give you hope, or tell you the one secret doctors don't

  • want you to know, but it's a fact of life. You get old, systems break down, then you

  • die. WellThanks for watching Human. Speaking of things coming to an end, this episode marks

  • the end of season 2 of Human. Don't worry, we're still working on videos behind the

  • scenes, so make sure to subscribe to us here on Youtube and drop a comment if you have

  • a topic you want me to cover in Season 3. Thanks for watching

I've got a little challenge for you this week. If you're able to, stand on one foot

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B1 balance hair fluid cochlea semicircular membrane

Why These Hidden Organs Keep You From Falling Over

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    林宜悉 posted on 2021/02/25
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