as I was told from early education that the air we currently breathe in contains 21% oxygen and 77-ish% of nitrogen and the rest are other particles.
So I have a dumb question on what the body uses nitrogen we breathe in for?
In: 387
Nothing really – except for evolved microorganisms (A. vandii if I’m remembering correctly) that are symbiotic with some plants and are capable of “fixing,” (I.E. using) nitrogen gas.
Two fun facts: 1) possibly the most impactful invention of the 20th century was the Haber-Bosch process, which has led to huge usage of nitrogen fertilisers for crop growth. Without it, more than half of humans on the planet now would’ve starved to death. 2) Your body doesn’t sense what you’re breathing in, only that carbon dioxide is being breathed out. You can “drown,” in 100% nitrogen with no physical sign of it except loss of consciousness. So be careful in environments where that may be possible!
Nothing. Nitrogen in the air is in N2 form, which under normal condition doesnt want to react.
From chat GPT
When you inhale the air from the atmosphere, which consists of about 78% nitrogen, into your lungs, several things occur:
1. Inhalation: During the inhalation process, you breathe in air through your nose or mouth. This air contains a mixture of gases, including nitrogen.
2. Passage through Airways: The inhaled air travels down your windpipe (trachea) and branches into smaller airways called bronchi, eventually reaching the tiny air sacs in your lungs called alveoli.
3. Gas Exchange: In the alveoli, oxygen from the air diffuses across the thin walls of the alveoli into the bloodstream. This oxygen is then transported by red blood cells to various parts of your body for use in cellular respiration.
4. Nitrogen Remains Inert: Nitrogen, however, does not significantly participate in this gas exchange process. It remains inert and does not chemically react with your body. Instead, it continues to circulate through your respiratory system with each breath and is eventually exhaled back into the atmosphere when you breathe out.
In summary, when you inhale nitrogen from the atmosphere into your lungs, it doesn’t play a direct role in oxygenating your body. Instead, it primarily serves as a diluent gas in the air you breathe, and it’s exhaled without undergoing any significant chemical changes within your body.
Like it does for most things, nitrogen does absolutely nothing.
It’s regarded as being inert for a reason. It doesn’t really interact with anything that isn’t a plant root.
The body takes in a volume of “air” (a composition of some dozen-or-so gasses at any one time.), takes some of the oxygen out of the 19-22% oxygen present in said volume (not even 1% of this present oxygen btw.) And then dumps it all out at once.
The reason some gasses, like H2S or CO are so deadly, is because our lungs can’t see the difference between it and oxygen. Both bind to blood cells like oxygen is supposed to, and are carried out through the body.
Think of it like ordering clothes as a man, then when your delivery arrives, it’s actually women’s clothes. “I can’t use this!” You might scream. You get mad, ask for a refund. Cells in your body are sort of like this, with the delivery man being your red blood cells. The only difference is that your body’s cells get so angry over this mixup that they literally just die.
You breathe air into your lungs.
Your lungs have millions of what are called air sacs, which are thin walled structures that get thin blood vessels (capillaries) very close to the surface.
The gasses in the air (oxygen, nitrogen, and others) are able to diffuse through the thin walls of the air sac and get into the blood.
Gasses can dissolve in liquids but not much. Just like if you open a bottle of soda water, the CO2 that’s dissolved in there doesn’t really want to be there. If you leave it to its own devices, most of it will leave. Oxygen and nitrogen are similar. They only want to dissolve into the blood a small amount.
The result is that they dissolve into your blood until they’re “saturated”, and the blood doesn’t want any more. At saturation, nitrogen and oxygen are entering and leaving your blood at the same rate so the concentration stays steady.
Nitrogen gas (N2) doesn’t get used by your body at all, so any dissolved nitrogen in your blood is just along for the ride. The small amount that’s able to dissolve is completely harmless. The dissolved nitrogen in your blood pretty much just stays at equilibrium with the atmosphere. There are some gas solubility equilibrium calculations that you may learn in grade 12 chemistry that can be used to estimate how much nitrogen is in your blood.
Dissolved oxygen isn’t very useful in itself, because not much can dissolve. That’s why your blood has Hemoglobin. Hemoglobin is a protein molecule that’s able to “pick up” oxygen. It essentially scoops it up. This lets your blood carry oxygen much more efficiently than if it were only using dissolved oxygen.
Oxygen gets used in what you might consider mini-combustion reactions. It’s reacted with energy dense molecules like glucose, releasing carbon dioxide. Hemoglobin does two jobs, it also picks up CO2 when it’s done carrying oxygen, and it happily releases it in the lungs, allowing CO2 to diffuse through the air sac membrane into the lungs in the air where it will be breathed out.
What really helps the knowledge “click” for me is remembering that its not like my stomach, where everything that gets taken in gets processed and used/broken down. Most of what you inhale, including nitrogen and most of the oxygen, gets pushed right back out. We breath in air that’s about 21% oxygen, and we breath out air that’s about 17% oxygen (depending on how long we hold our breath). So about 4/5ths of the oxygen we breathe in doesn’t get used either, because it doesn’t have a chance to diffuse into our blood before we breathe it back out again.
One reason we don’t breathe in and hold our breath to use every last scrap of oxygen is because it’s not efficient. The whole process is limited by how fast oxygen will diffuse through the air sac membrane and into our blood, which isn’t very fast (hence why we have millions of air sacs). Diffusion is a “mass transfer” phenomenon, and the rate of diffusion depends on the material and the difference in concentration on either side. Higher concentrations of oxygen in the air result in a higher rate of diffusion out of the air and into the blood.
When we hold our breath, the oxygen percentage might drop to 15%, and the lower concentration slows down the diffusion. We get diminishing returns, and it results in lower blood oxygen. Given how easy it is to just push that stale air out and get a fresh breath, we just do that.
While it’s slightly off-topic to talk about oxygen diffusion, it’s part of the whole explanation about how and why we breathe out most of what we breathe in, and the same phenomenon affects nitrogen as well. We breathe it in, it dissolves into and out of our blood, and we breathe it back out. It’s just hitching a ride, like my grandpa who like to take the bus around town for no reason.
The 77% oxygen in the air is what prevents the oxygen from burning you alive.
Also the air is made from two nitrogen atoms which are triple bonded, this makes them extremely difficult to break apart and they don’t really serve a biological function in the human body, think of them as a buffer gas
Follow up question, why is there so much nitrogen in the air?
Nitrogen is inert but it still serves an important function. It does defuse across the alveolar membrane some but mostly it helps keep alveoli open so that O2 can be defused into your bloodstream and CO2 can be defused out of the blood stream. Also if there were less nitrogen in the atmosphere then we would be breathing a higher percentage of 02 and that would be toxic when it reached 0.5 bar. Normal o2 at sea level is approximately 0.21.
Nothing. The funny thing is also that plants very much need nitrogen but they don’t get it from the air either.
A whole lot of nitrogen in the air and nobody wants it. It does help scatter light and give us a blue sky though so that’s nice.
Nothing, it just leaves. Nitrogen gas in the air is pretty hard for life to do anything with.
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