Zoology - Breathing and Exchange of Gases Question with Solution | TestHub

Partial pressure of O₂ in the atmospheric air is 158 mm of Hg and that of CO₂is 0.3 mm of Hg. Partial pressure of oxygen PO₂in alveolar air is 100 mm Hg and it is only 40 mm Hg in the arterial capillaries of the lungs. Therefore, oxygen from the alveolar air rapidly diffuses due to its higher PO₂into the blood capillaries. Hence, Partial pressure of CO₂(PCO₂) is lower in the air inside the lungs.