buffer [ME, buffe, to cushion] , a substance or group of substances that tends to control the hydrogen ion concentration in a solution by reacting with hydrogen ions of an acid added to the system and releasing hydrogen ions to a base added to the system. Buffers minimize significant changes of pH in a chemical system. Among the functions carried out by buffer systems in the body is maintenance of the acid-base balance of the blood and of the proper pH in kidney tubules. See also blood buffers, pH.
