And so the CO2 molecules are expelled from the cell and they enter the blood plasma of the capillary, the nearby capillary. Now, because carbon dioxide is nonpolar, only a very small portion, about 5%, will actually remain dissolved in the blood plasma. The majority of it, the rest of it will enter the cytoplasm of the red blood cell. Now, once inside the red blood cell, what we have to do is we have to convert the carbon dioxide, a non polar molecule, into a polar form, namely the bicarbonate. And that's because we want to be able to dissolve the carbon dioxide in the blood. So the majority of the carbon dioxide in the red blood cell will follow this reaction pathway.