Gravity and the human body - Jay Buckey
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Not SyncedSome of the issues that are important
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Not Syncedif you want to have people in space
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Not Syncedfor long periods of time.
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Not SyncedOne is that people will tend
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Not Syncedto lose bone and muscle mass.
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Not SyncedWe know this.
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Not SyncedIf you have to put a cast on your leg
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Not Syncedand you take the cast off after a few weeks,
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Not Syncedyou'll see that your muscles have shrunk in size.
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Not SyncedAnd if you measured the bone strength,
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Not Syncedyou'd also see that might have gone down a little bit, too.
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Not SyncedAnd so, it's very interesting that our body has that ability
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Not Syncedto adapt to the loads that are put on it,
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Not Syncedso that bones and muscles aren't static,
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Not Syncedthey're always changing.
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Not SyncedWhile we think of bone as being this solid thing
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Not Syncedthat doesn't change very much,
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Not Syncedit changes too.
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Not SyncedAnd it turns out that in weightlessness,
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Not Syncedyou lose bone.
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Not SyncedAnd then you also cause the muscles
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Not Syncedthat work against gravity,
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Not Syncedwhat are called the postural muscles,
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Not Syncedthey'll start to shrink and lose strength.
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Not SyncedThere are other things in the cardiovascular system,
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Not Syncedthe heart and blood vessels.
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Not SyncedAnd if you think about it,
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Not Syncedstanding up in gravity
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Not Syncedmeans you have to work against gravity
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Not Syncedin order to keep blood pumping to your head.
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Not SyncedSo, if you couldn't keep blood pumping in your head,
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Not Syncedyou'd pass out every time you stood up
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Not Syncedbecause when you're lying down,
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Not Syncedyou don't have to push against gravity.
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Not SyncedBut when you stand up,
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Not Syncedyou got to work against gravity
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Not Syncedto keep blood flowing to your head.
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Not SyncedAnd your heart and blood vessels
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Not Syncedhave a really nicely worked-out system
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Not Syncedto make that happen every time.
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Not SyncedBut that system can also change in weightlessness.
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Not SyncedAnd then the other area that changes
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Not Syncedis the system that has to do with balance.
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Not SyncedAgain, maintaining your balance
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Not Syncedis something that you're doing against gravity, right?
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Not SyncedIf you didn't have gravity present,
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Not Syncedyou wouldn't have to worry about falling.
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Not SyncedBut you obviously do have to worry about falling
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Not Syncedand we have a very highly developed sense of balance
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Not Syncedto keep us upright
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Not Syncedand to keep us from falling.
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Not SyncedAnd when you see what skaters do,
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Not Syncedyou realize just how exquisite a system it is.
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Not SyncedBut when you go into weightlessness,
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Not Syncedyour balance system changes.
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Not SyncedYou don't really notice it
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Not Syncedwhile you are in weightlessness,
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Not Syncedbut when you come back,
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Not Syncedyou do notice it,
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Not Syncedthat your balance has changed
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Not Syncedand you have a little bit of trouble
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Not Syncedmaintaining your balance.
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Not SyncedAnd what it shows is that while you're in space,
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Not Syncedyour brain is trying to allow you
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Not Syncedto function in weightlessness.
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Not SyncedSo it re-adapts you to be weightless,
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Not Syncedwhich you don't notice until you come back
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Not Syncedand find out that you are now back on Earth
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Not Syncedwith a balance system that's been adapted to space.
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Not SyncedYou know, all life developed here on Earth
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Not Syncedwith gravity being present,
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Not Syncedso life evolved under the influence of gravity,
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Not Syncedand then we grow up with gravity being present,
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Not Syncedso we learn how to walk
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Not Syncedand catch a ball
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Not Syncedand ice skate
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Not Syncedor whatever,
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Not Syncedall with gravity being present.
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Not SyncedAnd what if you were to grow up without gravity?
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Not SyncedWhat about the systems that depend on gravity,
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Not Syncedlike your muscles
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Not Syncedor your balance system
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Not Syncedor the heart and blood vessels?
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Not SyncedWould they develop normally,
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Not Syncedor would they be different in some way?
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Not SyncedOne reason why you might think
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Not Syncedit would go down a different pathway
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Not Syncedis from an experiment
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Not Syncedthat was done some time ago
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Not Syncedby two neuroscientists
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Not Syncedcalled Hubel and Wiesel.
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Not SyncedAnd what they did, was they had a kitten
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Not Syncedand they put a patch over the eye of the kitten.
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Not SyncedAnd then the kitten grew up to be a cat,
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Not Syncedand they removed the patch.
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Not SyncedAnd so, the question is,
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Not Syncedcan the cat see out of that eye?
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Not SyncedNow, there's nothing wrong with the eye, right?
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Not SyncedBut it just hasn't seen anything,
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Not Syncedthere's no,
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Not Syncedit hasn't been any light coming in.
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Not SyncedAnd the answer is that the cat can't see out of that eye
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Not Syncedbecause what happens is that the brain
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Not Syncedgoes down a different pathway
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Not Syncedwhen it develops and the connections
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Not Syncedthat would ordinarily develop to that eye
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Not Synceddon't develop.
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Not SyncedAnd that can't be undone,
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Not Syncedthat's a permanent change.
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Not SyncedSo, the brain of that cat
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Not Syncedis fundamentally different from the brain of a cat
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Not Syncedthat grew up seeing out of that eye.
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Not SyncedThat cat grew up with a different brain, in essence.
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Not SyncedSo, then you wonder
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Not Syncedwhat about gravity?
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Not SyncedWhat if you don't have the forces
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Not Syncedthat gravity produces?
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Not SyncedIs your balance organ going to develop
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Not Syncedin the same way,
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Not Syncedor will it be different?
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Not SyncedIf somebody grew up in space,
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Not Syncedcould they come back to Earth and function,
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Not Syncedor would they really be a different person?
- Title:
- Gravity and the human body - Jay Buckey
- Description:
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View full lesson: http://ed.ted.com/lessons/gravity-and-the-human-body-jay-buckey
Our bodies function necessarily under the presence of gravity; how blood pumps, a sense of balance and bone growth are all due to life in a world where gravity is an inescapable reality. Armed with experiments from neuroscientists David Hubel and Torten Wiesel, astronaut Jay Buckey presents a thought experiment: How would our bodies work without the force of gravity?
Lesson by Jay Buckey, animation by TED-Ed.
- Video Language:
- English
- Team:
- closed TED
- Project:
- TED-Ed
- Duration:
- 04:46
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Jessica Ruby edited English subtitles for Gravity and the human body - Jay Buckey | ||
Jessica Ruby edited English subtitles for Gravity and the human body - Jay Buckey | ||
Jessica Ruby accepted English subtitles for Gravity and the human body - Jay Buckey | ||
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Andrea McDonough edited English subtitles for Gravity and the human body - Jay Buckey |