Question

Gases diffuse over the respiratory surface because of ______.

• A. $p{O}_2$ is more in alveoli than in blood
• B. $p{O}_2$ is more in blood than in tissues
• C. $pC{O}_2$ is more in alveoli than in blood
• D. $pC{O}_2$ is more in blood than in tissues

Answer 1

The correct option is A $p{O}_2$ is more in alveoli than in blood

The partial pressure of oxygen is high in the alveoli and low in the blood of the pulmonary capillaries. oxygen diffuses across the respiratory membrane from the alveoli into the blood. The partial pressure of carbon dioxide is high in the pulmonary capillaries and low in the alveoli.

So, the correct answer is option A.