Researchers are studying pulmonary gas exchange in various physiological and pathological states using animal models. In one experiment, the partial pressure of oxygen (PO₂) in the upper airways is determined to be 150 mm Hg while breathing ambient air at rest. Analysis of the respiratory gases in a particular lung segment reveals the following: Which of the following best explains these respiratory gas findings?

Question

Quizplus · Accepted Answer

Eductional Objective: Gas exchange between the alveoli and pulmonary capillary blood depends on both perfusion and diffusion. The exchange of O₂ and CO₂ in a normal individual at rest is perfusion-limited, so alveolar and capillary partial pressures are equal. Situations in which O₂ exchange becomes diffusion-limited (eg, emphysema, pulmonary fibrosis) cause a large gradient between alveolar and capillary PO₂; PCO₂ is less affected due to the greater diffusing capacity of CO₂.

Researchers Are Studying Pulmonary Gas Exchange in Various Physiological and Pathological