By what mechanisms can the kidney compensate for changes in pH?

An important function of the kidney is to regulate the pH of the extracellular fluid

1. Excretion of H⁺ ions with generation of HCO₃^–
2. Buffering of H⁺ to promote excretion:
   • Phosphate buffer system
   • Ammoniagenesis and ammonia buffer system
3. Reabsorption of filtered bicarbonate (usually >99%)