If air is made up of 78% Nitrogen, our blood uses Oxygen and we exhale Carbon dioxide, what happens to nitrogen?
In: Biology
Atmospeheric pressure is made up of the sum of the partial pressures of its constituents, Nitrogen, Oxygen, a small amount of CO2 and a very small amount of other stuff. In normal circumstances the “pressure” of oxygen in our blood is less than the pressure in the atmosphere. It’s not really pressure but that’s a good analogy. So, when we breathe we absorb the O2 and use it. This produces Carbon Dioxide which we need to excrete. The “pressure” of CO2 in our blood is higher than the pressure of CO2 in the air so it flows from the blood to the air in our lungs as the O2 flows from the air into our blood.
The pressure of Nitrogen in our blood is the same as the pressure of Nitrogen in the air and at these pressures it has no effect on the body. What is interesting is what happens when the air pressure changes. As we ascend, in an airplane or climbing up a mountain etc.. the air pressure reduces and the difference in pressures between our blood and the air changes in the same way. If we go too high and the air pressure is too low the difference between the pressure of O2 in the air and our blood becomes too low. This is why people climbing high mountains require supplemental O2, same as pilots in some circumstances. With respect to N2 an interesting thing happens when the pressure gets too great. A scuba diver may breathe compressed air to the same pressure as the water pressure around him. The deeper he goes the more air pressure is required and the pressure of the gases in his body (which keep in equilibrium by moving in or out of the blood through the lung membranes) rise as well. And at a certain point the pressure of the N2 in the blood causes intexication. A very high pressure of O2 can also be toxic.
The “Bends” is caused when a diver ascends too fast. The high pressure of N2 in his blood does not have time to balance (move acress the lung membrane from the blood into the air) out with the suddenly lower air pressure in his lungs and makes bubbles in the blood which can be very troublesome.
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