Which organ plays a key role in acid-base balance by regulating HCO3- and H+?

Which organ plays a key role in acid-base balance by regulating HCO3- and H+?

• A. The lungs.
• B. The kidneys.
• C. The liver.
• D. The heart.

Answer: (B)

Kidneys regulate bicarbonate (HCO3-) and hydrogen ions (H+), making them the primary long-term regulator of acid-base balance. They reclaim nearly all filtered HCO3- in the kidney tubules, excrete H+ into urine, and generate new bicarbonate through metabolic processes (such as glutamine metabolism to ammonium and bicarbonate). This combination directly adjusts the body's base and acid load, helping maintain blood pH over hours to days. The lungs influence pH more quickly by changing CO2 levels but don’t regulate HCO3- and H+ directly; the liver and heart are not the main players in this specific regulation.

Kidneys regulate bicarbonate (HCO3-) and hydrogen ions (H+), making them the primary long-term regulator of acid-base balance. They reclaim nearly all filtered HCO3- in the kidney tubules, excrete H+ into urine, and generate new bicarbonate through metabolic processes (such as glutamine metabolism to ammonium and bicarbonate). This combination directly adjusts the body's base and acid load, helping maintain blood pH over hours to days. The lungs influence pH more quickly by changing CO2 levels but don’t regulate HCO3- and H+ directly; the liver and heart are not the main players in this specific regulation.