Acid Production
Start with the big picture
Acid production includes volatile acid, chiefly carbon dioxide formed during aerobic metabolism, and non-volatile or fixed acids arising from protein and lipid metabolism. The lungs remove carbon dioxide by exhalation. Fixed acids—including sulfuric, phosphoric, lactic acids and ketones—require renal handling. The kidneys reabsorb nearly all filtered bicarbonate, secrete hydrogen ions, and excrete acid in buffered forms: titratable acid, mainly associated with phosphate, and ammonium. Ammonium excretion is an important adaptive mechanism. As hydrogen ions are excreted, new bicarbonate is generated and returned to plasma. Together, these processes explain how metabolic acid loads are managed and why renal function is central to maintaining acid-base balance.
What you'll learn
- Distinguish volatile acid from fixed acid by source and route of elimination.
- Identify major metabolic sources of fixed acids.
- Describe the kidneys’ roles in bicarbonate reabsorption and hydrogen-ion secretion.
- Compare titratable acid and ammonium excretion.
- Explain how renal hydrogen-ion excretion contributes to plasma bicarbonate.
Continue your study
Work through the complete notes and reinforce the topic with the study tools available in the full lesson.
