What do the kidneys regulate to maintain pH balance?

The kidneys play a critical role in maintaining the body's pH balance through various mechanisms, primarily by regulating the concentration of key ions, including sodium, potassium, and calcium.

In the context of acid-base physiology, the kidneys help to excrete hydrogen ions (H+) and reabsorb bicarbonate (HCO3-), which is essential for maintaining a stable blood pH. By managing the levels of sodium and potassium, the kidneys influence other electrolytes and acid-base balance. Sodium is crucial for various physiological processes, including fluid balance and nerve function, while potassium is vital for muscle function and cardiac rhythm. Calcium is essential for many cellular functions, and its regulation also helps influence pH balance indirectly by affecting muscle and nerve activity.

By regulating these key ions together, the kidneys not only maintain electrolyte balance but also ensure that the extracellular environment remains within the normal pH range, which is typically around 7.35 to 7.45. Therefore, the kidneys’ regulation of these specific ions directly impacts overall acid-base homeostasis in the body.