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Here's why you shrink every day - Video học tiếng Anh
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Here's why you shrink every day
Here's why you shrink every day
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Subtitles (57)
0:00
- You know how tall you are, right?
0:01
But what if how tall you think you are
0:03
isn't how tall you actually are right now?
0:06
It's 6:30 AM and I'm 190 centimeters tall.
0:09
As I go through my day, I'll take a lot of steps,
0:12
we carry heavy things,
0:13
and sometimes I lift very heavy things.
0:15
And all that walking, moving,
0:16
and existing does weird things to our bodies.
0:19
By bedtime, I'm actually only around 188 centimeters tall.
0:22
Our height maxes out in the morning after we wake up
0:25
and it bottoms out at night,
0:26
because the second that you get out of bed
0:28
your spine starts battling gravity.
0:30
In between every vertebra in your spine is a disc,
0:33
but that disc isn't hard like bone.
0:35
It's squishy because it's made out
0:37
of collagen and cartilage.
0:38
These discs act like tiny springs
0:40
that absorb shock as you move.
0:42
And as gravity pulls on you,
0:44
it compresses the discs in your spine.
0:46
They lose fluid,
0:47
which causes them to literally deflate
0:50
and causes you to shrink.
0:51
That shrinkage adds up
0:52
because your discs make up about a quarter
0:55
of how tall your spine is.
0:56
Now in Zero-G where there's nothing pushing on their spines,
0:59
astronauts can get about 3% taller.
1:02
Unfortunately on earth,
1:04
we're getting squished every waking minute of the day.
1:07
All this made me wonder though.
1:08
Does that mean giraffes get shorter every day too?
1:10
I mean, no one's managed to measure one every day,
1:13
but the answer's almost certainly yes.
1:15
I mean, carrying a 500 pound crane-like neck,
1:17
that's a serious amount of compression.
1:19
So a giraffe probably loses a few inches of height
1:21
before bedtime too.
1:22
Every mammal's spinal discs squish under pressure all day
1:26
and they rehydrate while sleeping.
1:27
Even for regular four-legged animals with horizontal spines.
1:31
Now the back doesn't just escape gravity,
1:33
it acts like a biological suspension bridge pulled tight
1:36
by powerful muscles to keep the spine from sagging.
1:39
But that squeezes those discs horizontally too.
1:41
But all it takes to reclaim our lost height
1:44
is just laying down to sleep,
1:45
when those discs fill with fluid again
1:47
and swell back up to the normal size.
1:49
But eventually we lose this war with gravity
1:52
'cause as we age, our spinal discs lose their elasticity,
1:55
they don't bounce back like they used to.
1:57
So the older we get,
1:58
we shrink every day and then we stay shrunk.
2:01
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