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In decompression sickness why does nitrogen gas come out as bubbles? Is it because under high pressure the nitrogen gas was converted into liquid nitrogen and during the process of coming to the surface (depressurisation)the liquid nitrogen evolved out as gas bubbles in the arteries and veins?

I have tried to compare the bubble formation to the concept that gas cylinders contain liquid LPG that comes out as gas.

A follow up question: If my concept is right i.e. the gases are being liquefied at high pressure (under water) how does our body deal with the liquid oxygens and carbondioxides? As far as I know there is no mechanism to transport liquid oxygen and carbondioxide in blood.

Tyto alba
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1 Answers1

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Nitrogen is not liquefied in these conditions at all.

What happens is that when pressure increases, nitrogen's solubility in blood increases (this is a general property of gases: their solubility in liquids always increases with pressure)

When a diver decompresses properly (i.e. quite slowly) the nitrogen is released from the blood slowly (due to the now reduced solubility of the nitrogen) and without consequences to the decompressing diver.

But when the diver decompresses too fast or suddenly what happens is analogous to what happens when you suddenly open a carbonated drinks can: the sudden drop in pressure causes the carbonated drink to release its $CO_2$ suddenly and bubbles then form.

In the case of the suddenly decompressing diver, small nitrogen bubbles formed in the blood stream cause the symptoms of caisson disease.

Gert
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