Which plays an essential role in maintaining acid-base homeostasis?

• A. Liver
• B. Lungs
• C. Kidneys
• D. Pancreas

Answer: (C)

Acid-base balance is governed by how the body handles bicarbonate and carbon dioxide, with the lungs providing rapid control of CO2 and the kidneys providing long-term regulation of bicarbonate and hydrogen ion excretion. The kidneys are essential because they adjust the acid-base status by reclaiming filtered bicarbonate, secreting hydrogen ions into urine, and generating new bicarbonate through processes like ammoniagenesis and titratable acidity. This renal work allows the body to correct metabolic disturbances over hours to days, maintaining pH despite ongoing acid or base loads. While the lungs rapidly modify pCO2 to influence pH, their effects are immediate but transient; other organs like the liver or pancreas don’t regulate systemic acid-base balance as the kidneys do.