Renal Compensation for pH Regulation
Start with the big picture
Filtered bicarbonate is reclaimed mainly in the proximal tubule through coordinated activity involving NHE3, carbonic anhydrase, and basolateral NBCe1. Further reclamation occurs along other nephron segments. In α-intercalated cells, secreted hydrogen ions are buffered in urine, while bicarbonate generated within the cells returns to plasma. Ammoniagenesis from glutamine provides another route for acid excretion and new bicarbonate formation. Net acid excretion reflects titratable acid and ammonium excretion minus urinary bicarbonate. Renal responses adapt to changes in pH and carbon dioxide, and hormones and potassium status influence distal hydrogen-ion secretion. These mechanisms help explain why particular tubular defects can alter urine pH and contribute to metabolic acidosis.
What you'll learn
- Describe how the proximal tubule reclaims filtered bicarbonate.
- Explain how α-intercalated cells generate bicarbonate while secreting hydrogen ions.
- Identify the roles of titratable acid and ammonium in renal acid excretion.
- Relate changes in pH, carbon dioxide, hormones, and potassium to renal acid-base handling.
- Distinguish renal tubular acidosis patterns described in the lesson.
Continue your study
Work through the complete notes and reinforce the topic with the study tools available in the full lesson.
