ipH

• c)
• The range of [H⁺] compatible with life is approximately 16 - 160 nanomoles/L (pH: 6.77 - 7.80). It should be emphasized that the pH value per se is of limited significance unless seen in the context of the clinical condition of the patient.

We Learn by Understanding

An adult produces roughly 1 mmoles (10⁶ nanomoles) of fixed acid (H⁺) per Kg of body weight per day. The ECF H⁺ content is normally about 12 nanomoles. Therefore, the daily acid production is usually a million times larger than the ECF H⁺ content.

• Fixed acid load is diluted in body fluids which lessens its impact on cell function, then it is buffered by ECF (40%) and ICF buffer bases (60%). A major buffer base is bicarbonate (HCO₃^-):
• H⁺ + HCO₃^- <---> H₂CO₃ <---> H₂O + CO₂
• The carbon dioxide is quickly eliminated through the lungs, whereas the bicarbonate consumed is eventially replenished by the kidney in the course of net acid execretion. Two thirds of the acid load is ultimately execreted by the kidneys in the form of ammonium which derived from glutamine metabolism.