ABSTRACT
An acid–base buffer solution resists a change of pH when an acid or base is added to it. A good buffer solution must maintain a nearly constant pH when either acid or base is added. Plasma and proteins are effective buffers because both their carboxyl and free amino groups dissociate. At the physiological blood pH of 7.4, small changes in the relative compositions cause a large pH change. The buffer functions most effectively when its pKa is within one unit of the desired pH of the solution. Deoxygenated haemoglobin dissociates more readily than oxygenated haemoglobin, making it a better buffer and weaker acid. Buffering by bicarbonate results in bicarbonate reabsorption, whereas buffering with phosphate and ammonia results in bicarbonate regeneration. Excess acid is buffered by calcium carbonate in bone and it contributes to renal osteodystrophy. Haemoglobin levels are reduced due to depressed production of new red blood cells from a diminished erythropoietin secretion.
