Question

The pCO\textsubscript{2 of alveolar blood is ___________} mmHg.

• A. 30
• B. 104
• C. 45
• D. 90

Hint:

Remember: Normal alveolar values — pO\textsubscript{2} ≈ 104 mmHg and pCO\textsubscript{2} ≈ 45 mmHg.

Answer 1

The Correct Option is C

Step 1: Understanding alveolar gas values.
Alveolar blood gas values are maintained by efficient exchange of gases between alveoli and pulmonary capillaries.
Step 2: Normal pCO\textsubscript{2 value. Under normal physiological conditions, the partial pressure of carbon dioxide (pCO\textsubscript{2}) in alveolar blood is approximately 45 mmHg.
Step 3: Analysis of options.
(A) 30: Incorrect — too low for alveolar blood.
(B) 104: Incorrect — corresponds to pO\textsubscript{2}, not pCO\textsubscript{2}.
(C) 45: Correct — normal alveolar pCO\textsubscript{2}.
(D) 90: Incorrect — abnormally high.
Step 4: Conclusion.
The pCO\textsubscript{2} of alveolar blood is 45 mmHg.