The process that causes the imbalance is classified based on the cause of the disturbance (respiratory or metabolic) and the direction of change in pH (acidosis or alkalosis).

[2] Mixed disorders may feature an acidosis and alkosis at the same time that partially counteract each other, or there can be two different conditions affecting the pH in the same direction.

Several buffering agents exist which reversibly bind hydrogen ions and impede any change in pH.

Acid–base imbalances that overcome the buffer system can be compensated in the short term by changing the rate of ventilation.

The kidneys are slower to compensate, but renal physiology has several powerful mechanisms to control pH by the excretion of excess acid or base.