What will be the pO2 and pCO2 in the atmospheric air compared to those in the alveolar air?

Question

(i) pO2 lesser, pCO2 higher
(ii) pO2 higher, pCO2 lesser
(iii) pO2 higher, pCO2 higher
(iv) pO2 lesser, pCO2 lesser

Answer 1

(ii) pO2 higher, pCO2 lesser
The partial pressure of oxygen in atmospheric air is higher than that of oxygen in alveolar air. In atmospheric air, pO2 is about 159 mm Hg. In alveolar air, it is about 104 mm Hg.
The partial pressure of carbon dioxide in atmospheric air is lesser than that of carbon dioxide in alveolar air. In atmospheric air, pCO2 is about 0.3 mmHg. In alveolar air, it is about 40 mm Hg.