Hydrogen Ion Concentration Is Precisely Regulated
Precise H+ regulation is essential because the activities of almost all enzyme systems in the body are influenced by H+ concentration. Therefore, changes in hydrogen concentration alter virtually all cell and body functions.
Compared with other ions, the H+ concentration of the body fluids normally is kept at a low level. For example, the concentration of sodium in extracellu-lar fluid (142 mEq/L) is about 3.5 million times as great as the normal concen-tration of H+, which averages only 0.00004 mEq/L. Equally important, the normal variation in H+ concentration in extracellular fluid is only about one mil-lionth as great as the normal variation in sodium ion (Na+) concentration. Thus, the precision with which H+ is regulated emphasizes its importance to the various cell functions.