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Why don't we have just ONE nostril? - Video học tiếng Anh
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Why don't we have just ONE nostril?
Why don't we have just ONE nostril?
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Subtitles (43)
0:00
- Why does our nose have two holes instead of just one?
0:03
For one, that's pure nightmare fuel. Yikes.
0:06
But part of it is because of how our bodies
0:08
are programmed to grow,
0:09
and it's actually super important to how we breathe.
0:12
But hold that thought.
0:13
We're part of a group
0:14
called bilaterally symmetrical animals.
0:16
That means if you split us down the middle, head to tail,
0:18
we're basically a mirror image on both sides
0:20
and that's determined all the way down
0:22
in our genetic instructions.
0:23
But wait. Our mouth just has one hole.
0:25
Well, the surprising answer
0:27
is that having two nostrils actually helps the nose
0:29
smell and breathe better
0:30
because it turns out your nostrils
0:32
are constantly taking turns.
0:33
Sometimes one nostril breathes 60% and the other is 40%.
0:37
Sometimes it's 70% and 30%.
0:39
Blood vessels in the nose tighten and swell
0:42
to switch which nose hole is more open,
0:44
and then every two to six hours or so,
0:46
they trade and the other nostril takes over.
0:48
And this swap repeats all day and all night.
0:51
This is all completely automatic.
0:52
You don't even have to think about it,
0:54
although you're probably thinking about it right now,
0:56
trying to figure out which nostril's in charge.
0:58
Letting one nostril rest
0:59
helps us manage the humidity of the air that we breathe,
1:02
And having two nostrils
1:03
also helps make our sense of smell richer and deeper.
1:06
See, the open nostril catches more
1:08
of the fast-acting scent chemicals
1:10
when the resting nostril can absorb scent chemicals
1:12
that are more slow burners.
1:14
They take longer to seep into the system.
1:16
So together you get this richer sense of smell
1:18
than one nostril alone.
1:21
(startling music)
1:22
Made you look!
1:23
Follow me for more cool science videos.
