The pressure gradient for the diffusion of CO in the lung is: A) Equivalent to the partial pressure of inspired CO B) The difference between inspired and expired CO C) Equal to the alveolar minus capillary partial pressure of CO D) Equal to the alveolar-arterial O₂ gradient

Question

Quizplus · Accepted Answer

The pressure gradient for diffusion of CO in the lungs is the difference in partial pressure between the alveolar and capillary compartments. This is because diffusion of gases occurs from higher to lower partial pressures, and the alveolar partial pressure of CO is always higher than the capillary partial pressure. The partial pressure of inspired CO (option A) is not relevant in this context, as inspired air has very low levels of CO. Option B is incorrect, as expired air contains CO even in healthy individuals. Option D refers to a different concept (the difference between arterial and alveolar partial pressures of oxygen), and is therefore incorrect.

The Pressure Gradient for the Diffusion of CO in the Lung