The mildly alkaline plasma pH of about 7.4 is maintained despite an acid load normally produced in the body. O About 13,000 to 20,000 mmol of CO2 are produced by aerobic metabolism each day. Nonvolatile acids cannot be converted to gases under physiological circumstances. The most important nonvolatile acid is sulfuric acid. Phosphoric acid is produced from the metabolism of nucleic acids and phospholipids.
Lactic acid accumulates during exercise.
Finally, during pathological states, other nonvolatile acids can be produced to a significant extent. Although most people have a net production of nonvolatile acid, they also produce alkali from the ingestion of milk, fruit, and vegetables. Remember, these are the salts of the weak organic acids, not the acids themselves, that are ingested. A buffer solution is one that has the capacity to minimize deviations in pH when a strong acid or base is added to it. A buffer solution contains a weak acid or weak base and a salt of the acid or base.