Why does carbon dioxide exchange from pulmonary capillaries to alveoli increase during exercise, rather than oxygen uptake increasing by the same ratio?

💡 Explanation

During exercise, carbon dioxide production increases in muscles, leading to a higher concentration gradient between blood and alveoli; because carbon dioxide diffuses more readily down this increased gradient, its exchange increases. Therefore, CO2 exchange rises disproportionately, rather than oxygen uptake increasing similarly, because oxygen diffusion depends more on alveolar ventilation.

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