As blood passes through the tissues, all of the following actions occur EXCEPT that

CO2 is formed in the tissues and diffuses into the blood. A small fraction dissolves in plasma, where it exes a paial pressure. The remainder diffuses into the red blood cell, where it can either bind directly to the free NH2 groups on hemoglobin (a carbamino compound) or become hydrated in the presence of the enzyme, carbonic anhydrase, to form carbonic acid. This acid is in equilibrium with its dissociated form of H+- and HCO3- .