What is the normal arterial pH range?

• A. 7.25
• B. 7.35-7.45
• C. 7.50
• D. 7.60

Answer: (B)

Maintaining a narrow pH range in arterial blood is essential because enzyme activity and cellular function are highly sensitive to hydrogen ion concentration. The normal arterial pH range is 7.35 to 7.45. This tight window is kept by buffering systems and by the balancing actions of the lungs (CO2) and kidneys (bicarbonate). If pH falls below 7.35, it’s acidemia; if it rises above 7.45, it’s alkalemia. The range 7.35–7.45 represents the healthy, balanced zone, so it is the correct choice.