What happens to Nitrogen

[sigma]

When you breath in Oxygen is absorbed into the blood stream and Carbon Dioxide is exhaled. What happens to Nitrogen and all the other gases that make up air.

[joggerjayne]

In simple (!) (ie, non scientific) terms ...

Nothing.

You breathe it in, use up a little bit of the oxygen, and breathe it out again, with a bit of corbon dioxide.

Nitrogen is not absorbed into your tissues at normal pressure.

[ChuckFickens]

You breath it back out again.

The the only thing that really changes to any significant level between air you breath in and air you breath out is the oxygen and CO2 levels, the oxygen decreases by about 5% the CO2 increases by about 5% (and the humidity is much higher)

[ChuckFickens]

We must stop meeting on these (vaguely) diving related questions, Jayne :)

[joggerjayne]

I agree with Chuck.

=0)

[joggerjayne]

Yes Chuck, and I thought I'd better say it was the simplified answer, just in case anyone pops up and says ...

"Aaaah, yes, but ..."

... and posts a lecture about nitrogen absorption at increased partial pressures.

[ChuckFickens]

Also why I included the words "significant level" as there are other trace differences between inhaled and exhaled air :)

[jake-the-peg]

Well not quite

Your body tissues absorb some of that Nitrogen too (let's stick to Nitrogen as it's way the most important).

In normal day to day living that doesn't have any effct on you at all - humans have evolved with it.

It does make a big differnce in scuba diving.

As you dive deeper your body absorbs gas at a higher and higher pressure, the Oxygen gets used up but the Nitrogen is absorbed.

When you ascend that Nitrogen tries to expand back again and if you've absorbed too much or ascend too quickly that can form tiny bubbles causing excruciating pain - the infamous bends!

Some tissues absorb and release quickly and are less of a risk - unless you really rocket to the surface. Other slow tissues - things like cartilege are much more at risk - that's why most bends get people's joints.

Professional divers who need to stay down a long time or dive very deep use Helium instead of Nitrogen. Which apart from making your voice squeeky is a very small atom and can escape from the body very easilly. stopping them from getting bent.

Nitrogen also acts as a narcotic at depth so it useful for avoiding such effects too

Eventually though as you get deeper and deeper the Oxygen you breate actually becomes toxic and attacks the nervous system and this rather limits the depths humans can dive at.

The effects of pressure and gasses on the body is really quite complex

[ChuckFickens]

To be fair though, Jake the question isn't about diving. on the surface your body will have reached a point of nitrogen saturation with the tiny quantity it is able to absorb and no more will be absorbed with each subsequent breath. if you were to climb a mountain then some of the absorbed nitrogen would be "off gassed" due to the lower air pressure and on decent a tiny amount of nitrogen would be reabsorbed to bring the level back to the normal saturation levels for sea level. but assuming you stay at the same height (or depth) then the amount of nitrogen exhaled would be as near as damn it to the same as the amount inhaled.

[jake-the-peg]

No I know but those other gasses do get absorbed by your body tissues.

The diving case is an interesting illustration of that fact.

[jomifl]

The average person at sea level has about 1.5 litres of nitrogen dissolved in body tissues (blood included as it is a tissue).

[joggerjayne]

It seems such a waste of a gas.

Nitrogen is about 80% of the air ... and we don't need it !

If there was 80% Oxygen, we could all feel high all of the time, and we'd nerver get hangovers.

[jake-the-peg]

No but you'd have raging forrest fires and giant spiders.

One of the factors limiting the size of insects and other similar creatures is the percentage of oxygen in the atmosphere. That was higher in the distant past which is why you had giant creepy crawlies then but not now

[dundurn]

There is an example of the diving situation in reverse. Astronauts on the ISS and the Space Shuttle operate at normal atmospheric pressure and breathe air (and therefore nitrogen). When conducting spacewalks however their spacesuits operate at significantly lower pressures and they breathe pure oxygen. Before undertaking an EVA, therefore, they spend some time at a lower pressure to gradually purge their systems of nitrogen otherwise they would have a form of decompression sickness in space.

[joggerjayne]

Interesting, Dundurn.

I'd never thought about that.

[jomifl]

Jogger.. when you dive to 120 feet the partial pressure of the oxygen in the air you are breathing is quadrupled so that it is equivalent to 80% oxygen at normal atmospheric pressure. Do you get a high? or nitrogen narcosis?