[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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We'll see you next time.