HOW TO BREATHE WELL? Why is oxygen needed and CO2?

When life began to develop on Earth, the composition of its atmosphere was completely different than today. Based on estimates by scientists, it is believed that at that time the atmosphere contained about 20 percent carbon dioxide (CO2). Does that mean that today's human being would also be able to breathe well in such a world? It turns out that absolutely... why I will explain further. Over thousands of years, as a result of many complicated physical, chemical, and biological processes, as well as catastrophes related to the impacts of large asteroids and volcanic activity, the amount of CO2 significantly decreased and currently stands at only 0.03 percent. The change is huge. Such a small content of carbon dioxide is not good for our bodies. In order to breathe well, a human being needs oxygen of course, but for this oxygen to reach all the appropriate places in our bodies (organs and cells), carbon dioxide is also necessary. Because this gas plays a very important role in the process of breathing, our bodies had to somehow adapt to this situation. This was achieved by creating a small internal, "good" atmosphere in the lung alveoli. At this moment, biology confirms that the optimal concentration of CO2 in the alveoli should be 5 - 6.5% (or expressed differently by partial pressure - about 40 mg Hg), which is almost 200 times more than in the inhaled atmospheric air. In this way, the human body was able to ensure that the change in the composition of the atmosphere did not significantly affect its functioning. However, another serious problem arose - most of our population breathes improperly, we take in too much air and exhale too much. As a result of this excessive breathing (hyperventilation), we deprive our lungs of valuable CO2, and therefore the inhaled oxygen is simply not utilized by our bodies. This would not be a problem if the atmosphere in which we live contained about 6% CO2. However, the minimal content of carbon dioxide in the atmosphere causes that by breathing improperly, we unnecessarily deprive our lung alveoli of it, and thus simply disrupt the mechanisms of our body (our cells function at a suboptimal level of oxygen supply). Many processes in our body begin to work differently.Why does nitrogen oxide improve the oxygenation of the body?Interestingly, it has been recently found that breathing too much air not only reduces the amount of oxygen reaching the tissues and organs, but also adversely affects another gas that is crucial in the process of oxygenating the body, nitrogen oxide. It wasn't until the end of the 20th century that the presence of this gas in exhaled air was discovered. While it was known earlier that it is produced in blood vessels causing their dilation, the fact of its formation in the nasal sinuses was surprising. During breathing through the nose, a large amount of nitrogen oxide is produced in the nasal sinuses. This means that further along with the air, it is transferred to the lungs. Being there, it supports the process of dilating blood vessels, increasing the uptake of oxygen into the blood. Thus, by breathing through the nose, we use the existing source of nitrogen oxide in us (in the nasal sinuses), the natural ability of our body to improve the process of oxygen absorption. Breathing through the mouth, on the other hand, does not reach the nasal sinuses, so nitrogen oxide simply remains "unused" there.