Exemplar Problems

Question:

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

(i) pO2 lesser, pCO2 higher

(ii) pO2 higher, pCO2 lesser

(iii) pO2 lower, pCO2 higher

(iv) pO2 lesser, pCO2 lesser

Answer:

(iii) pO2 lower, pCO2 lower In atmospheric air, the partial pressure of oxygen (pO2) is higher (around 159 mmHg at sea level), while the partial pressure of carbon dioxide (pCO2) is lower (around 0.3 mmHg). In alveolar air, after gas exchange, pO2 is lower (around 104 mmHg) because oxygen is taken up by the blood, and pCO2 is higher (around 40 mmHg) due to the release of carbon dioxide from the blood into the alveoli during exhalation.