ABSTRACT
The major metabolic use of O2 is in the oxidation of fuels in the mitochondrion for the generation of energy either in the form of chemical bond energy in adenosine triphosphate (ATP) or as heat. This results in the production of CO2 and water. CO2 is eliminated from the body in expired air from the lungs, and reaches the lungs from mitochondria by a reversal of the oxygen cascade route.
