If air is made up of 78% Nitrogen, our blood uses Oxygen and we exhale Carbon dioxide, what happens to nitrogen?
In: Biology
It doesn’t get absorbed; N2 is a very inert gas, it doesn’t react with much. The majority of what you exhale is N2.
The nitrogen is just *there*. Inconsequential. We breathe it in, we breathe it out. We could live without it entirely and not notice it. Only under high pressures or sudden pressure losses does it impact us, and in both cases it’s a problem.
Nothing. It just hangs out, taking up space. Reacting with nothing at all because of its triple bonds with itself.
It goes in and goes right back out. At normal air pressures it doesn’t really interact with our bodies chemistry.
At high pressures, like SCUBA diving, it gets absorbed in to our bodies and can cause problems.
All the nitrogen you breathe in just comes back out on the breath out. It doesn’t get absorbed, or released.
* The air you breathe in is ~78% nitrogen, ~21% oxygen, and ~1% other stuff.
* **The air you breathe out is ~78% nitrogen, still ~17% oxygen, only ~4% carbon dioxide**, and ~1% other stuff
As you can see, the mix we call “air” goes into the lungs, then *some* of the oxygen gets absorbed, some CO2 exits the blood into the lungs, and the nitrogen and other stuff just comes back out too.
All the nitrogen is there and doesn’t reacts with anything. Also you statement is technically wrong we breathe in Oxygen rich air and exhale carbon dioxide rich air.
We breathe it in, we breathe it out.
The nitrogen content of inhaled and exhaled air remains essentially constant in normal circumstances.
A lot of people are saying that it does nothing but that’s not true. While Nitrogen enters and exits the lungs without any chemical transformation, it does something in the lungs called “tenting.”
Basically, because oxygen is absorbed in the lungs, if the atmosphere was just oxygen, as you breathe in and the oxygen gets absorbed, your lungs would collapse as ask of the volume gets transported into your blood. But because there’s nitrogen in your lungs too, it tents the lungs open and keeps them from collapsing in on themselves.
We don’t *just* exhale carbon dioxide. Basically, we inhale air, and we exhale air. What changes is the proportions of the gases in that air. The air we inhale has about 20% oxygen and less than 0.1% CO2. The air we exhale has about 16% oxygen and 4% CO2. The rest was, and is, nitrogen.
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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