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The response to mild acidosis is actually a very complex process involving neural control of blood pressure and respiration rate. However, the most effective component of this response, the one that really rectifies the situation, is the expulsion of CO₂ in the lung. The bicarbonate buffering system is best suited to deal with acidosis, in part because respiration expels CO₂ and thereby diminishes H⁺.

In metabolically active tissues, such as muscle during intense exercise, production of CO₂ (and acid, in the form of lactic acid) can lead to a transient fall in local pH.

The bicarbonate buffering system of blood can respond quickly to mild acidosis (between pH 7.15 and 7.35) by adjusting the CO₂ release rate in the lungs. This adjustment can be made very rapidly--as anyone knows who has just climbed a steep flight of stairs!