Which value is at the upper limit of the normal pH range?

Which value is at the upper limit of the normal pH range?

• A. 7.40
• B. 7.45
• C. 7.50
• D. 7.35

Answer: (B)

Normal arterial blood pH is kept within a narrow range, about 7.35 to 7.45. The highest value inside that range is 7.45, which represents the upper limit of normal. Values higher than this, such as 7.50, indicate alkalemia beyond normal balance. A value like 7.40 sits squarely in the middle of the normal range, and 7.35 marks the lower limit. The body maintains this balance through buffers, respiratory regulation of CO2, and renal regulation of bicarbonate, because even small shifts in hydrogen ion concentration can affect enzyme activity and cellular function.

Normal arterial blood pH is kept within a narrow range, about 7.35 to 7.45. The highest value inside that range is 7.45, which represents the upper limit of normal. Values higher than this, such as 7.50, indicate alkalemia beyond normal balance. A value like 7.40 sits squarely in the middle of the normal range, and 7.35 marks the lower limit. The body maintains this balance through buffers, respiratory regulation of CO2, and renal regulation of bicarbonate, because even small shifts in hydrogen ion concentration can affect enzyme activity and cellular function.