#Breathing #NitrogenUtilization #GasExchange
When we breathe, what do we do with the nitrogen contained in the air? 🤔
As we inhale and exhale, our bodies undergo a complex process of gas exchange, taking in oxygen and releasing carbon dioxide. But what about the nitrogen that makes up the majority of the air we breathe? How does our body handle this essential yet inert gas? Let’s dive into the fascinating world of nitrogen utilization in the human body.
Understanding Nitrogen in the Air
Before delving into how our bodies process nitrogen, it’s essential to grasp the role of this abundant gas in the air. Nitrogen makes up approximately 78% of the Earth’s atmosphere, making it the most prevalent gas we inhale with each breath. While nitrogen itself does not play a direct role in the body’s energy production or metabolic processes, it still serves a crucial function in the respiratory process.
Nitrogen Utilization in the Body
Contrary to popular belief, our bodies do not utilize nitrogen in the same way they utilize oxygen for energy production. Instead, nitrogen primarily serves as a carrier gas, facilitating the exchange of oxygen and carbon dioxide in the lungs. The respiratory system acts as a gateway for the transfer of gases, allowing oxygen to enter the bloodstream and carbon dioxide to be expelled from the body.
As we breathe in, the nitrogen contained in the air enters our lungs alongside oxygen. However, unlike oxygen, which is utilized in metabolic processes to produce energy, nitrogen remains relatively inert within the body. Despite this, nitrogen still plays a vital role in maintaining the delicate balance of gases within the respiratory system.
The Role of Nitrogen in Gas Exchange
Although nitrogen itself does not undergo metabolic reactions within the body, it does play a crucial role in the process of gas exchange. As oxygen is absorbed into the bloodstream and carbon dioxide is released from the body, nitrogen serves as a diluent, ensuring that the exchange of gases occurs in a controlled and regulated manner.
Additionally, the presence of nitrogen in the air we breathe helps to maintain the structural integrity of the respiratory system. The inert nature of nitrogen makes it an ideal component of the air, providing the necessary pressure to support the delicate alveoli in the lungs while preventing the collapse of airways.
Excretion of Nitrogen
While our bodies do not actively utilize nitrogen for energy production or metabolic processes, the inert gas still undergoes a process of excretion. As we exhale, the nitrogen that we ingested with each breath is expelled from the body, along with the by-product of carbon dioxide. This continuous cycle of gas exchange ensures that the levels of nitrogen remain balanced within our respiratory system.
In certain cases, such as when scuba diving at depths with increased pressure, the solubility of nitrogen in the bloodstream can lead to a condition known as nitrogen narcosis or “rapture of the deep.” This phenomenon underscores the importance of proper gas exchange and the delicate balance of nitrogen within the body.
In summary, while our bodies do not directly utilize nitrogen in the same way they utilize oxygen for energy production, the inert gas still plays a crucial role in the process of gas exchange within the respiratory system. From serving as a diluent to maintaining the structural integrity of the lungs, nitrogen’s presence in the air we breathe is essential for sustaining life.
By understanding the role of nitrogen in the body, we gain a deeper appreciation for the intricate processes that occur with each breath we take. As we continue to explore the complexities of human physiology, the utilization of nitrogen serves as a reminder of the remarkable symbiosis between our bodies and the environment.
Nuetral gases like nitrogen do nothing. They don’t get absorbed into our blood. Gases like carbon dioxide and carbon monoxide DO get absorbed into our bloodstream and replace the oxygen. We can get rid of it, but this is why these gases are bad; they take the “slot” for the oxygen in our hemoglobin.
Nitrogen gas does cross into the bloodstream, like most everything you breathe in that’s a gas or small molecule. Passive diffusion rules the day in the lungs and moves things towards the area of lower concentration (which, in this case, is into the blood).
While most gases go into the blood, CO2 moves out because there is less CO2 in the atmosphere compared to the blood. It’s diffusing out because that’s the way the gradient occurs. O2 moves in because our cells love that and use it up really quickly, so there is less in the blood. Most of the time, we only talk about O2 and CO2 because they are the most important when you are teaching about the chemistry of biology.
Biologically speaking, nitrogen gas is not really that important to creatures with lungs. This is because it is not very chemically reactive with the enzymes that we have. N2 has a triple bond between the nitrogen atoms, and it’s very happy like that and has little desire to share electrons with anybody. Since it doesn’t react under the ‘biological conditions’ of the blood, it’s not generally helpful or harmful. It’s just kind of… there…
(Side note – it’s a totally different story if you are a nitrogen fixing bacteria, though. They love N2 and do lots of cool stuff with it. This comment, however, is not about them.)
Compare that to O2, which is a hella reactive molecule. If it wasn’t for plants and algae pumping it out, the oxygen in the atmosphere would eventually disappear.
That said, nitrogen gas in your blood can be a problem if you are scuba diving and surface too quickly. It’s what causes the bends. But it’s not actually doing any chemical reaction in this case – it’s just bubbling out of blood like the bubbles from a freshly opened Coke.
Just to be clear, nitrogen in other forms is really important to us living things. Nitrates, nitrites, ammonia, etc. are all over our metabolic pathways. But note how all of these are a single nitrogen atom bound to other elements. They don’t have more than one nitrogen in a row. Two nitrogens in a row is an inert gas, three in a row makes an azide (these are super toxic, and some cause BIG booms if you poke too hard).
Fun little add on – if you breathe something in that doesn’t diffuse back out of the lungs, you eventually will pee it out. Thanks, kidneys!
A nitrogen atom “wants” nothing more in its existence than to find another nitrogen atom with which to form a nice, stable triple bond that precludes anything else from bonding with it. You probably know that compounds with “nitro” in their names are frequently explosive, and this is why: those nitrogens are incredibly eager to dump the losers they’re bonded with and find their nitrogen soulmates for an eternity of beautiful monogamy.
Nitrogen in air is already dinitrogen – two nitrogen atoms connected by a stable triple bond that takes a ton of effort to break. So most organisms, including humans, don’t bother, and get it from food. That ends up being way more efficient even though nitrogen that isn’t N2 already is much rarer.
There are a few microorganisms called diazotrophs (“di” two “azo” nitrogen “troph” eater) that occupy that niche that most organisms don’t bother with – they perform “nitrogen fixation” usually by turning N2 into NH3 (ammonia). These are crucial to the “nitrogen cycle” by which every other living thing gets the nitrogen it needs. Most nitrogen-fixing organisms use nitrogenase enzymes that don’t work very well when exposed to oxygen, and so live in low-oxygen environments. A lot of them have symbiotic relationships with plants, where they live in or around the roots and trade fixed nitrogen for the safety those roots provide.
You inhale nitrogen with the O2 (etc). The oxygen dissolves in your lungs and goes to do oxygen things. Your lungs also release CO2. The nitrogen barely dissolves/gets absorbed, so you just exhale it back out (with most of the O2 you inhaled, BTW).
Breathe it in
Sits in lungs
Breathe it out.
A small amount exists as a dissolved gas in your bloodstream (as does oxygen, and other gasses), but relatively minute with little transfer in or out at the alveolar level.