Exchange Of Gases

During transport of CO by RBCs, carbonic acid is formed by the action of enzyme carbonic anhydrase. The carbonic acid of RBCs dissociates into hydrogen (H) and bicarbonate ions (HCO). Most of bicarbonate ions(HCO) formed within RBCs diffuse out into the blood plasma along the concentration gradient. Exit of bicarbonate ions, considerably change ionic balance between the plasma and the erythrocytes (RBCs). To restore this ionic balance, the chloride ions diffuse from the plasma into the erythrocytes. This movement of chloride ions is called chloride shift (Hamburger's phenomenon).