Which ion is primarily responsible for buffering metabolic acids in the blood?

Which ion is primarily responsible for buffering metabolic acids in the blood?

• A. Calcium
• B. Phosphate
• C. Potassium
• D. Bicarbonate

Answer: (D)

Bicarbonate acts as the main extracellular buffer against metabolic acids. When metabolism produces acids, hydrogen ions rise in the blood and bicarbonate ions quickly neutralize them, forming carbonic acid. Carbonic acid then converts to CO2 and water, and the CO2 is expelled by the lungs. This dynamic between bicarbonate and CO2 helps keep blood pH stable, with the kidneys supporting the system by reabsorbing or producing bicarbonate and by excreting hydrogen ions as needed. Phosphate can provide buffering, especially inside cells and in the urine, but it is not the primary buffer in the blood. Potassium and calcium help with overall electrolyte balance and cellular function, but they do not serve as the principal buffering system for metabolic acids.

Bicarbonate acts as the main extracellular buffer against metabolic acids. When metabolism produces acids, hydrogen ions rise in the blood and bicarbonate ions quickly neutralize them, forming carbonic acid. Carbonic acid then converts to CO2 and water, and the CO2 is expelled by the lungs. This dynamic between bicarbonate and CO2 helps keep blood pH stable, with the kidneys supporting the system by reabsorbing or producing bicarbonate and by excreting hydrogen ions as needed. Phosphate can provide buffering, especially inside cells and in the urine, but it is not the primary buffer in the blood. Potassium and calcium help with overall electrolyte balance and cellular function, but they do not serve as the principal buffering system for metabolic acids.