What mechanisms does the body have to maintain a normal pH and how quickly do they act?

Defence
Mechanism
Constituent Altered
Timeframe
1st Line
Buffer Systems
  • Extracellular buffer systems (primarily bicarbonate system)
[H+]
Seconds
1st Line
Buffer Systems
  • Intracellular buffer systems (primarily phosphate system)
[H+]
Hours
2nd Line
Respiratory Regulation
  • Alteration in alveolar ventilation
[CO2]
Minutes - Hours
3rd Line
Renal & Hepatic Regulation
  • Tubular secretion of acid
  • Tubular resorption of bicarbonate
[HCO3-]
Hours - Days