How does the urinary system maintain acid-base balance in the body?

The urinary system plays a crucial role in maintaining the acid-base balance in the body primarily by excreting hydrogen ions and reabsorbing bicarbonate. This process is essential for regulating the pH of the blood and other bodily fluids.

When the body needs to decrease acidity, the kidneys excrete hydrogen ions into the urine. This excretion reduces the amount of acid in the bloodstream, effectively raising the pH. Simultaneously, the kidneys reabsorb bicarbonate from the filtrate back into the bloodstream. Bicarbonate acts as a buffer, helping to neutralize excess acids in the body. By balancing the levels of hydrogen ions and bicarbonate, the kidneys contribute significantly to the overall pH homeostasis.

This regulatory mechanism allows the body to adapt to various metabolic processes and conditions that can alter acid-base balance, ensuring that it remains within the narrow range needed for optimal physiological function.