Normal arterial blood pH range is approximately?

• A. 7.0–7.2
• B. 7.35–7.45
• C. 7.55–7.65
• D. 7.2–7.3

Answer: (B)

Normal arterial blood pH is kept within a narrow window to support enzyme activity and metabolic processes. The typical reference range is about 7.35 to 7.45. Values within this range reflect a balanced acid–base state maintained by buffers (especially bicarbonate), respiratory control of carbon dioxide, and renal control of bicarbonate and hydrogen ions. When pH falls below this range, the blood becomes acidic (acidemia), and when it rises above it, the blood becomes too basic (alkalemia). The other ranges are either too acidic or too alkaline to be compatible with normal physiology.