ABSTRACT
Carbon dioxide (CO2) is normally present in the atmosphere in a concentration of 0.03-0.04 per cent volume of dry air. This represents a partial pressure of 0.23-0.30 mmHg. CO2 is one of the products of metabolism of protein, carbohydrates and fats produced in the mitochondria of cells in approximately the same volume as oxygen is consumed:
The resultant CO2 has to be transported from the tissues by the circulation and eliminated by exhalation from the lungs.
