The partial pressures (in mm Hg) of oxygen (O2) and carbon dioxide (CO2) at alveoli (the site of diffusion) are :
- pO2 = 159 and pCO2 = 0.3
- pO2 = 104 and pCO2 = 40
- pO2 = 40 and pCO2 = 45
- pO2 = 95 and pCO2 = 40
Answer
(2) pO2 = 104 and pCO2 = 40
Solution
As per NCERT (Table: partial pressures in mm Hg):
Atmospheric air: pO2 = 159, pCO2 = 0.3
Alveoli: pO2 = 104, pCO2 = 40
Deoxygenated blood: pO2 = 40, pCO2 = 45
Oxygenated blood: pO2 = 95, pCO2 = 40
∴ At the alveoli, pO2 = 104 and pCO2 = 40 mm Hg.
Answer: (2)