Question

At the alveoli, the rate of diffusion of O₂ and CO₂ is dependent on the __________.

a) partial pressure gradients for O2 and CO2
b) surface area of alveolar membranes
c) thickness of the respiratory membrane
d) all of the above

Answer 1

At the alveoli, the rate of diffusion of O₂ and CO₂ depends on the partial pressure gradients, surface area of alveolar membranes, and thickness of the respiratory membrane, making the answer d) all of the above.

Step-by-step explanation:

At the alveoli, the rate of diffusion of O₂ and CO₂ is dependent on the partial pressure gradients for O₂ and CO₂, surface area of alveolar membranes, and thickness of the respiratory membrane. This means the correct answer is d) all of the above. Diffusion of gases such as oxygen and carbon dioxide across the respiratory membrane occurs due to Dalton's law, where each gas exerts pressure independently, and Henry's law, indicating that the amount of gas that dissolves in a liquid is a function of its partial pressure. Oxygen diffuses from the high partial pressure in the alveoli to the lower pressure in the blood, and carbon dioxide moves from the higher pressure in the pulmonary capillaries to the lower pressure in the alveoli.

Additionally, the solubility of gases plays a role, with carbon dioxide being far more soluble than oxygen, which aids its diffusion despite the smaller partial pressure gradient. The large surface area available for gas exchange and the thinness of the alveolar-capillary membranes also facilitate the efficient diffusion of gases.