Oxygen makes up about 65% of the mass of the adult body—most of this is in the form of water.
Oxygen also makes up approximately 50% of the mass of the Earth’s crust and 21% of the atmosphere (air)—the rest of the atmosphere is mostly nitrogen (78%). The Earth is the only planet in the solar system with a high percentage of oxygen.
Oxygen Characteristics:
Oxygen is critical for chemical reactions that keep the body alive, including the reactions that produce adenosine triphosphate (ATP) —the molecule used for energy. Brain cells are sensitive to a lack of oxygen because of their demand for a high-and-steady production of ATP.
Brain damage is likely within five minutes without oxygen (cerebral hypoxia, and death is likely within ten minutes. A steady supply of oxygen is indispensable for cardiac function and viability.
According to the US National Library of Medicine Open Chemistry Database https://pubchem.ncbi.nlm.nih.gov/compound/977
An adult human, at rest, inhales 1.8 to 2.4 grams of oxygen per minute. This amounts to more than 6 billion tonnes of oxygen inhaled by humanity per year.
At a resting pulse rate, the heart consumes approximately 8-15 ml O2/min/100 g tissue. This is significantly more than that consumed by the brain (approximately 3 ml O2/min/100 g tissue) and can increase to more than 70 ml O2/min/100 g myocardial tissue during vigorous exercise.
The molecular formula for oxygen is O~2~, which represents the chemical bonding of two oxygen atoms.
Posted on 05/31/2018 at 02:05 PM
