Breathing Theory

[WQFTruckster]

Ok, I know that the deeper you go, the more air you consume with each breath (@33 feet your consumption is twice as much as at the surface), because the air is regulated to the same pressure as the water around you. Thus, the deeper you go, the more dense the air is that you are breathing, correct? Now, if the air is twice as dense, wouldn't that mean that there are twice as many oxygen molecules in the same volume of air? If thats true than it seems like we would only need to breathe half as often at this depth to have the same amount of oxygen supplied to our lungs as at the surface. I guess this does not hold true for some reason, because I feel the need to breathe just as often at depth as at the surface. Although the reverse seems to be true: At very high altitudes you are more likely to become "out of breath" due to the low air density. Am I missing something?

 

[RDP]

The body only uses a small percentage of the oxygen you breath in each breath. This is the same at the surface as it is below.

 

[WQFTruckster]

The body only uses a small percentage of the oxygen you breath in each breath. This is the same at the surface as it is below.

Then why do we breathe as often as we do?

 

[pete340]

I guess this does not hold true for some reason, because I feel the need to breathe just as often at depth as at the surface... Am I missing something?

Yup, you're missing carbon dioxide in your blood. That's what drives the urge to breath, not the oxygen content.

 

[pete340]

Then why do we breathe as often as we do?

So we can perform rescue breathing. 21% oxygen inhaled, 16% exhaled. You only need about 10% to sustain life.

 

[WQFTruckster]

Yup, you're missing carbon dioxide in your blood. That's what drives the urge to breath, not the oxygen content.

But it seems like the lungs would also be able to expel twice as much carbon dioxide per breathe if the density was twice as high. Guess not.

 

[RDP]

But it seems like the lungs would also be able to expel twice as much carbon dioxide per breathe if the density was twice as high. Guess not.

Nope. The body will work as usual; it just takes more gas to inflate the lungs.

 

[WQFTruckster]

So if you become short of breath at high altitude, is that caused by lack of oxygen, or build up of carbon dioxide?

 

[tndiveinstruct1]

The reason we breathe as often as we do is because the body must get rid of the waste products from work, and in the case it is Carbon Dioxide ( CO2 ).

When we breathe, we are performing 2 actions. One is the intake of O2, and the other is CO2. The body is monitoring the level of CO2 in the blood stream and when it reaches a certain point, then a signal is sent to the lungs to inhale and exhale.

The body doesn't use all of the O2 that is inhaled. As a matter of fact it only uses about 5% of the inspirated O2. This is the reason why CPR works.

Hope this helps....

Randy Cain

 

[WQFTruckster]

You only need about 10% to sustain life.

What about 5% oxygen at twice the density, thus the same total amount of oxygen per lungfull?