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If you hold your breath, your lungs are still filled with air, which contains oxygen. So there's still some oxygen being transferred into your blood, it just ge

by brazzy 16y ago

If you hold your breath, your lungs are still filled with air, which contains oxygen. So there's still some oxygen being transferred into your blood, it just gets less and less. But actually, I suspect that the far more important factor is CO2, which leaves the blood in the lungs when there is air present.

berntb 16y ago
>>If you hold your breath, your lungs are still filled with air Just let me note -- don't hold your breath when there are pressure differences between your lungs and the surroundings!! You can find that in any scuba diving manual. (Edit: I do realize the parent poster probably knows this.)
- grinich 16y ago
  I've heard that when a diver surfaces quickly, they can expel a single breath all the way up. The air in their lungs continues to expand as they go through the pressure gradient. Has anyone actually experienced this? I'm assuming it would have to be a really quick surface (ie: dropping your weights), and after only a short dive or on pure O2.
  - bjelkeman-again 16y ago
    As a relatively experienced scuba diver I can say that the theory is correct. I haven't done an emergency ascent, as you describe, but standard practice is that you exhale on the whole way up or you will burst your lungs. Look at this table [1]: lung volume, depth m (ft) 2, 30m (99 ft) 3, 20m (66 ft) 4, 10m (33 ft) 8, 0 m (surface) So by ascending from 30 meters to the surface you expand the volume of the air in your lungs four times. (Of course, you don't want to do this, as you will most likely get decompression sickness, aka the bends.) [1] http://www.lakesidepress.com/pulmonary/books/scuba/sectionf.htm http://www.lakesidepress.com/pulmonary/books/scuba/sectionf....
ugh 16y ago
You are absorbing only 25 percent of the oxygen, which suggests to me that having air still in you lungs can be very helpful in keeping you conscious. Is that right?
- brazzy 16y ago
  That's exactly what I meant.

by brazzy 16y ago

berntb 16y ago

>>If you hold your breath, your lungs are still filled with air Just let me note -- don't hold your breath when there are pressure differences between your lungs and the surroundings!! You can find that in any scuba diving manual. (Edit: I do realize the parent poster probably knows this.)

grinich 16y ago
I've heard that when a diver surfaces quickly, they can expel a single breath all the way up. The air in their lungs continues to expand as they go through the pressure gradient. Has anyone actually experienced this? I'm assuming it would have to be a really quick surface (ie: dropping your weights), and after only a short dive or on pure O2.
- bjelkeman-again 16y ago
  As a relatively experienced scuba diver I can say that the theory is correct. I haven't done an emergency ascent, as you describe, but standard practice is that you exhale on the whole way up or you will burst your lungs. Look at this table [1]: lung volume, depth m (ft) 2, 30m (99 ft) 3, 20m (66 ft) 4, 10m (33 ft) 8, 0 m (surface) So by ascending from 30 meters to the surface you expand the volume of the air in your lungs four times. (Of course, you don't want to do this, as you will most likely get decompression sickness, aka the bends.) [1] http://www.lakesidepress.com/pulmonary/books/scuba/sectionf.htm http://www.lakesidepress.com/pulmonary/books/scuba/sectionf....

ugh 16y ago

You are absorbing only 25 percent of the oxygen, which suggests to me that having air still in you lungs can be very helpful in keeping you conscious. Is that right?

brazzy 16y ago
That's exactly what I meant.