The air we breathe is a mixture of gases, mostly nitrogen (75 percent). The oxygen content, however, is only 21 percent. This amount is sufficient for humans to oxygenate the blood for energy production.
Oxygen is vital
The oxygen is absorbed into the lungs with the respiration and reaches the blood from there. It binds to the red blood cells (erythrocytes) and is transported by them through the entire body to all organs. Locally, the cells absorb the oxygen and burn it in their power plants, the so-called mitochondria. This creates the vital energy that the body needs for metabolism and muscle movement. What remains is carbon dioxide with the chemical symbol CO 2, which is released by the cells back into the blood and exhaled through the lungs.
The reserves are only short
An adult inhales at rest per minute with about 16 breaths one to one and a half liters of oxygen. If the body is stressed, it needs more energy. Respiratory rate, heart rate and blood pressure increase to allow the blood to provide more oxygen to the cells for energy. Untrained increase under load their maximum oxygen uptake to up to three liters per minute. Top athletes come to twice as high values.
But who now discovered the oxygen?
The chemical compound O 2, the oxygen, discovered the Swedish pharmacist Carl Wilhelm Scheele in 1772 by chance in his chemical experiments. Because it promoted the combustion, Scheele called the found gas for a long time fire air. Only years later, the scientist Antoine Laurent Lavoisier recognized the important role of oxygen in breathing and became one of the founders of modern chemistry.