O2 in the blood

[KeroseneKeen]

I need some help with the following:
gases disolving in the blood (how)
Why Nitrogen is the controling gas for changing the bodys internal to equal changes in the outside pressure (diving, flying)
And Partial Pressures of gases
If anyone knows where i can get information on the web please help
Many thanks

[john_tullamarine]

(a) try any decent public library - texts in hyperbaric medicine and undergraduate texts in physics

(b) if you have any military mates - they should have some very relevant AvMed course notes

(c) if all else fails, your local AvMed examiner probably has some relevant texts in his/her surgery library

[Checkboard]

Nitrogen makes up approx. 80% of the atmosphere (at all levels) while Oxygen makes up 20%. There are some other trace gasses.

Oxygen is keen to react with other elements, and in the lungs it reacts with Haemoglobin to carry the oxygen around the blood steam. Nitrogen on the other hand has a tripple covalent bond and as such is pretty musch inert, so it doesn't react with blood, but it does dissolve in it - a big difference.

When Carbon Dioxide dissolves in Coke, and you open the bottle (i.e. reduce the pressure) you get bubbles of COČ coming out of solution, in the same way when you reduce the pressure in blood, you get bubbles of NČ coming out of solution.

[Code Blue]

<font face="Verdana, Arial, Helvetica" size="2">Nitrogen on the other hand has a tripple covalent bond and as such is pretty musch inert, so it doesn't react with blood, but it does dissolve in it - a big difference.

When Carbon Dioxide dissolves in Coke, and you open the bottle (i.e. reduce the pressure) you get bubbles of COČ coming out of solution, in the same way when you reduce the pressure in blood, you get bubbles of NČ coming out of solution</font>

Nitrogen dissolves also in tissues with a high fat content and this includes nerves. When suddenly released by decompression the gas forms bubbles as in the Coke analogy. Brains and spinal cords don't go better with any sort of bubbles disrupting them and paralysis or seizures are the result.

The gas comes out of solution in the tissues of the lungs producing shortness of breath. Bubbles in the joints and bone marrow produce intense pain.

Partial pressures can be estimated from gas laws. Assume sea level pressure is 760 mm Hg this would give a pN2 of approx 600 mm Hg and pO2 of 160 mm Hg in air at sea level.

Does this help?

The British Medical Journal publish a useful little booklet on Aviation Medicine which goes into a lot more detail.


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[This message has been edited by Code Blue (edited 24 May 2001).]

[KeroseneKeen]

Thanks for the info,
Further infor would be helpful

[tom775257]

Although off topic, just on an note of interest for smokers, carbon monoxide (as produce among other things in cigarettes) binds irreversably to Haemaglobin, thus rendering the molecule useless..

[This message has been edited by tom775257 (edited 25 May 2001).]