Topic overview

Start with the big picture

Renal acid–base regulation centers on reclaiming filtered bicarbonate and excreting acid. The proximal tubule performs much of the bicarbonate reabsorption and uses glutamine metabolism to generate ammonium and new bicarbonate. Further along the nephron, intercalated cells can secrete hydrogen ions or export bicarbonate, while urinary buffers help carry acid out of the body. The kidneys also fine-tune sodium, potassium, calcium, magnesium, and phosphate handling through segment-specific transport and hormonal signals. These systems intersect: for example, aldosterone affects hydrogen-ion secretion and potassium excretion, while parathyroid hormone influences calcium and phosphate transport. Understanding the segment and direction of each transport process helps organize this integrated role.