[MUSIC PLAYING]
Hey everybody.
It's me, Ben.
I'm back with another
Brain Stuff question.
Why can't we breathe underwater?
I haven't met everybody,
but everyone that I met
has not been able to
breathe underwater.
It's a good question when you
think about it, because water's
made up of hydrogen
and oxygen, right?
Well, it goes in the chemicals.
There's one thing we need
to remember about chemicals.
It's that, once they
react in certain ways,
they form compounds
that are often
nothing like the
original elements.
Think of two solo artists
from different bands.
They get together,
they make an album,
it sounds nothing like
the original music.
Man, when I say that out loud,
that is a terrible analogy.
Let's just look at
the chemicals instead.
For example, if you react
carbon, hydrogen, and oxygen
together one way,
you get glucose.
If you react them together
another way, you get vinegar.
If you react them together
in another way, you get fat.
If you react them in another
way, you get ethanol.
And glucose, fat,
ethanol, and vinegar
are nothing like each
other, but they're all
made from the same elements.
In the case of hydrogen
and oxygen gas,
if you react them together
one way, you get liquid water.
The reason we can't
breathe liquid water
is because the oxygen
used to make the water
is bound to two
hydrogen atoms, and we
can't breathe the
resulting liquid.
The oxygen that fish breathe
is not the oxygen in H2O.
Instead, the fish are
breathing O2, oxygen gas,
that's dissolved in that water.
Many different gases
dissolve in liquids.
We can see an example
of this all the time
with carbonated beverages.
In these beverages,
there's so much
carbon dioxide gas
dissolved in the water
that it rushes out in
the form of bubbles.
Fish breathe that
dissolved oxygen out
of the water using their
gills, and it turns out
that extracting the
oxygen isn't that easy.
Air has something like 20
times more oxygen in it
than the same volume of water.
Plus, let's remember that water
is a lot heavier and thicker
than air, so it takes a lot
more work to move it around.
The main reason that
gills work for fish
is the fact that fish
are cold blooded.
This reduces their oxygen
demands tremendously.
Warm blooded animals like
whales breathe air like people
do because it would
be hard to extract
enough oxygen using gills.
Human beings can't
breathe underwater
because our lungs don't
have enough surface area
to absorb enough
oxygen from water
and the lining of
our lungs is adapted
to handle air instead of water.
However, there have
been experiments
with humans breathing other
liquids, like fluorocarbons.
Fluorocarbons can
dissolve enough oxygen
and our lungs can
draw that oxygen out.
It's just that that
first breath where
you suck in the fluorocarbons
and they enter your lungs
is not very pleasant,
but it is possible.
So, that's the answer
to the question
why can't human beings
breathe underwater.
Thank you so much for watching.
Nobody try to breathe
underwater because unless you
are an extraordinary
person and maybe a mutant,
you're probably going to drown.
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And that's it.
We'll see you next time.
