ABSTRACT
The concentration of hydrogen (H) ions in body fluids is precisely regulated. Derangements of H
ion regulation can produce direct intracellular disturbances, including changes of enzyme activity, membrane excitability and energy production, and indirect systemic effects altering reflexes in the central nervous system and the release of hormones by the endocrine system. Although the body produces large quantities of volatile (carbonic acid) and fixed (non-carbonic) acids as a result of metabolism, the H ion concentration of body fluids is maintained at a low concentration (40 nmol/L). Acids are removed from the body by the lungs, kidneys and the gastrointestinal tract. When an imbalance between the production and removal of H ions occurs, the H ion concentration deviates over a narrow range of 20-160 nmol/L (pH 6.8-7.7).
