1. A mixture of an acid and its conjugate base (salt), such as H2C03/HC03-; H2P04-/ HP042-, that, when present in asolution, reduces any changes in pH that would otherwise occur in the solution when acid or alkali is added to it; thus, thepH of the blood and body fluids is maintained virtually constant (pH 7.45) although acid metabolites are continually beingformed in the tissues and C02 (H2C03) is lost in the lungs. See: buffers in whole blood.

2. To add a buffer to a solution and thus give it the property of resisting a change in pH when it receives a limited amount tacid or alkali.