Acid-base balance is one of the most important of the body’s homeostatic mechanisms.  It represents:  equilibrium, balance, a steady state.  This balance is important if the body is to effectively and continually perform its functions; without it cells cannot function properly.  While the body can tolerate slight deviations in its balance for short periods of time, over time, even slight imbalances can result in pronounced, potentially fatal changes in metabolic activity and essential body functions.

            Acids and bases continually enter the blood stream from absorbed foods and from the metabolism of nutrients at the cellular level.  Extremely high protein diets—those high in meats, fish, poultry, and eggs—produce a surplus of acid mineral residue taxing the body’s ability to remain in acid-base balance.  On the other hand, strictly vegetarian diets—those high in fruits and vegetables—produce a surplus of basic mineral residue also taxing the body’s ability to remain in acid-base balance.  If our body is to perform effectively and we are to survive a balance between acids and bases must be achieved.  Most acids and bases concerned with regulation of acid-base balance exist in the body as either a weak acid or a weak base.  The most influential acids are:  carbonic acid (H₂CO₃) and dissolved carbon dioxide gas (CO₂).  The most influential base is:  the bicarbonate (HCO₃^-) ion.

The infant, term or premature, is in a unique situation when it comes to acid-base balance.  First, the infant’s rate of metabolism is twice as great as that of the adult in relation to its body mass.  This translates into the production of twice as much acid as the adult.  Second, the functional development of the infant’s kidneys is not complete until about the end of the 1^st month of life.  As a result, the infant concentrates his urine to only 1½ times the osmolality of plasma as compared to the adult’s ability to concentrate his urine to 3-4 times the osmolality of plasma.  Consequently the infant has a natural tendency toward acidosis.

Although both acids and bases are important components of balance, it is the concentration and management of the hydrogen ions (H⁺) in extracellular body fluids that we are talking about when we discuss acid-base balance.  Hydrogen ions are continually entering the body fluids from carbonic, lactic, sulfuric, and phosphoric acids and from acidic ketone bodies.  Carbonic and lactic acids are formed as a result of the aerobic and anaerobic metabolism of glucose.  Sulfuric acid is created when sulfur-containing amino acids are oxidized and finally, phosphoric acid accumulates when certain phosphoproteins and ribonucleotides are metabolized as an energy source.  Acidic ketone bodies (acetone, acetoacetic acid, and beta-hydroxybutyric acid) accumulate during the incomplete breakdown of fats.  Even slight variations from normal in the H⁺ concentration can cause marked alterations in the rate of chemical reactions—some being slowed, others being accelerated.  As such, control of the H⁺ concentration is one of the most important facets of homeostasis.