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Comment by anonymous | Hacker News Reader

If only nature designed our lungs with a hole that can be used to fill and empty them, rather than the completely hermetically sealed ones we have!

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If you're holding your breath, which a naive swimmer likely is, then it's perfectly possible to rupture parts of your throat when the pressure differential grows too large. I'm not sure if that'd be fatal or not, but it'd definitely be dangerous.

The pressure differential, in this case, was three times that between normal pressure and vacuum.

The pressure differential for vacuum isn't enough to be dangerous by itself. The dangerous thing about vacuum exposure is that at that pressure your blood will boil at body temperature.

That's what they teach in diving class, but I've always wondered if the pressure wouldn't cause an impulse to exhale at some point?

Nope - the impulse to exhale comes from carbon-dioxide levels, not pressure in the lungs.

You'll go from feeling fine to acute pain to very dangerous damage pretty much momentarily.

A hole at one end. Put an empty, open bottle in a bowl of water facing downwards - where does the air go? Nowhere.

To be fair, the lungs compressible and more like a balloon than a bowl of water.

I can assure you, you can exhale upon ascent when inverted. (source: me, who used to log plenty of hours below 150fsw breathing mixed gasses).

Of course. But if you don't exhale deliberately you still risk barotrauma (I am a diver too see).

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