PATHOLOGY

Detailed explanation-1: -During exercise, the extraction of oxygen from blood coursing through exchange vessels lowers venous oxygen content compared to quiescent muscle. As a consequence, the arterio-venous oxygen content difference increases with activity.

Detailed explanation-2: -The lungs bring oxygen into the body, to provide energy, and remove carbon dioxide, the waste product created when you produce energy. The heart pumps the oxygen to the muscles that are doing the exercise. When you exercise and your muscles work harder, your body uses more oxygen and produces more carbon dioxide.