Begin 840 ml/min 590 ml/min 200 ml/min Alveoli Alveolar ventilation 4 U/min 200 ml co2 250mO2 750mo2→1000mO2 2800mCo2→2600mCo ung capillaries Lung capillaries Right Left Cardiac output/Right heart heart heart Tissue capillaries Tissue capillaries 750mO2 1000mO2 2800mCo2+2600mCo2 250mO2 200 ml cO2 Cells Cells In the lungs, the concentration gradients favor the diffusion of oXygen toward the blood and the diffusion of carbon dioxide toward the alveolar air; owing to the metabolic activities of cells these gradients are reversed at the interface of the blood and the active cellsIn the lungs, the concentration gradients favor the diffusion of oxygen toward the blood and the diffusion of carbon dioxide toward the alveolar air; owing to the metabolic activities of cells, these gradients are reversed at the interface of the blood and the active cells