Acid-Base Balance is defined as which of the following?

• A. Regulation of pH
• B. Measure of acidity or alkalinity
• C. Energy used at rest
• D. Normal Blood pH

Answer: (A)

Regulation of pH in body fluids is what acid-base balance refers to. It’s not merely the current acidity or alkalinity (that would be a pH reading); it’s the body's system of controls that keeps hydrogen ion concentration within a very narrow range. The body achieves this through buffers in the blood, plus adjustments by the respiratory system (which alters CO2 and carbonic acid) and the kidneys (which reabsorb or excrete bicarbonate and hydrogen ions). In arterial blood, pH is kept roughly from about 7.35 to 7.45, despite ongoing metabolism and feeding. The other options describe a measurement, energy use at rest, or the normal pH value itself, none of which capture the ongoing regulation that maintains a stable pH.