In external respiration,the partial pressures are: A)alveoli: high PO₂,low PCO₂; pulmonary capillaries: low PO₂,high PCO₂ B)alveoli: high PO₂,high PCO₂; pulmonary capillaries: low PO₂,low PCO₂ C)alveoli: low PO₂,high PCO₂; pulmonary capillaries: high PO₂,low PCO₂ D)alveoli: low PO₂,low PCO₂; pulmonary capillaries: high PO₂,high PCO₂

Question

Quizplus · Accepted Answer

During external respiration, gases diffuse between the alveoli and pulmonary capillaries. The alveoli have a high partial pressure of oxygen (PO2) and a low partial pressure of carbon dioxide (PCO2) due to the oxygen-rich air that has just been inhaled. In contrast, the pulmonary capillaries have a low PO2 and a high PCO2 as they are carrying oxygen-poor blood from the body's tissues to the lungs to be oxygenated. Therefore, option A is the correct choice.

In External Respiration,the Partial Pressures Are