Figure 3.

A cartoon [Fig. 6 from (1)] of a red blood cell and the reversible reaction of CO₂ and transmembrane exchanges taking place intra- and extracellularly during ¹⁸O exchange. The solid circles represent ¹⁸O and the open circles represent ¹⁶O. The fractions appended to the reaction arrows indicate the proportion of the total chemical reaction going to the designated product.