Breathing during Exercise

Abstract

THE main source of energy for the life process is the oxidation of dietary substrate in the mitochondria of cells, and the major catabolic end product is carbon dioxide. In a complex organism such as man, the ultimate source of oxygen and the "dump" for carbon dioxide, the atmosphere, is far removed from the cellular site of oxygen utilization and carbon dioxide production. Therefore, an interaction of physiologic mechanisms is required to allow gas exchange between the external environment and the cell (Fig. 1). These mechanisms link gas exchange at the cellular level with that at the lungs, while the . . .