The addition of CO2 to the blood generates _________ ions in the RBCs, which in turn stimulates RBCs to unload more oxygen.

A. A decrease in membrane thickness:Thinner respiratory membranes allow gases to diffuse more rapidly between alveolar air and blood. A decrease in thickness enhances gas exchange rather than slowing it.

B. An increase in alveolar surface area:A larger surface area provides more sites for diffusion, improving the efficiency of gas exchange. This change accelerates, rather than impedes, oxygen and carbon dioxide transfer.

C. An increase in membrane thickness:Thickening of the alveolar-capillary membrane, as occurs in conditions like pulmonary fibrosis or edema, increases the diffusion distance. This slows down the movement of oxygen and carbon dioxide between alveoli and blood, reducing gas exchange efficiency.

D. A decrease in nitrogen solubility:Nitrogen is largely inert and not actively exchanged in the lungs. Changes in its solubility have minimal effect on oxygen or carbon dioxide diffusion, so it does not significantly slow gas exchange.

E. An increase in respiratory rate:A higher respiratory rate enhances the ventilation of alveoli and maintains the concentration gradient for diffusion. This actually promotes faster gas exchange rather than slowing it.

A. 5%:This percentage is far too low to represent the volume of fluid returned by the lymphatic system. Only a small portion of capillary filtrate would be recovered at this rate, which would lead to significant interstitial fluid accumulation.

B. 85%:Approximately 85% of filtered fluid is reabsorbed directly at the venous end of capillaries, while the remaining 15% enters lymphatic vessels. The lymphatic system consistently retrieves this portion to prevent edema and maintain fluid balance.

C. 25%:A recovery of 25% would greatly overestimate the lymphatic contribution compared with the actual capillary reabsorption dynamics. This value does not match known physiological distribution of fluid return pathways.

D. 50%:If lymphatics recovered half of the capillary filtrate, the role of venous reabsorption would be significantly reduced, which does not reflect actual fluid handling. This percentage does not align with established cardiovascular–lymphatic physiology.