Normal Blood pH range is

• A. 7.0-7.3
• B. 7.5-7.8
• C. 7.35-7.45
• D. 6.8-7.2

Answer: (C)

Blood pH must be tightly regulated because even small changes alter enzyme activity, protein structure, and the excitability of nerves and muscles. The body keeps arterial pH in a narrow window, about 7.35 to 7.45, through buffering systems (like the bicarbonate buffer), respiratory control of CO2, and renal handling of H+ and bicarbonate. If pH drops below this range (acidemia), the central nervous system and heart can be suppressed, leading to confusion, lethargy, or worse. If pH rises above this range (alkalemia), neurons become more excitable, which can cause tingling, muscle spasms or arrhythmias. The normal range 7.35–7.45 reflects this delicate balance; values outside indicate clinically significant disorders.