[Acid-base equilibrium control system--red cell function].

The physiological functions of the red cell are oxygen transport, facilitation of carbon dioxide transport and control of acid-base equilibrium in the blood. The last function is closely related to the first two, which are cooperative to each other. The oxygen transport by red cells is characterized by high efficiency and regulation, which depend on allosteric properties of hemoglobin. The CO2 transport in the form of bicarbonate is also facilitated by the buffer action and the Haldane effect of hemoglobin. Hemoglobin is the major buffer system in the red cell. Its buffer power is strengthen through the Haldane effect. Carbonic anhydrase in red cell, together with band 3 protein in the membrane which facilitates the Cl-/HCO3- exchange across membrane, allows the conversion between CO2 and HCO3- and the buffering of carbonic acid to occur in a time scale of blood circulation.