In the systemic arteries, the partial pressure of carbon dioxide is 40 mm Hg. Partial pressure of a gas is the contribution of one gas to the total pressure exerted by all gases. Partial pressure of carbon dioxide in arterial blood is the portion of total blood gas pressure that is exerted by carbon dioxide. It decreases during heavy exercise, during rapid breathing, or in association with severe diarrhea, uncontrolled diabetes or the diseases of the kidney. It increases with chest injuries and respiratory disorders. In the systemic arteries, the partial pressure of oxygen is 100 mm Hg.
