Transport of Carbon Dioxide in Blood

As the bicarbonate ion diffuses out of the red cell, chloride ions diffuse in. Apart from driving the dissociation of the bicarbonate ion, the chloride shift is also responsible for the diffusion of water into the cell. This results in slight swelling of the cell in the venous blood with a resultant increase in the mean corpuscular volume of the red cells.

Thus, in summary it can be seen that hemoglobin has at least three important functions:

1.

As a carrier of oxygen

2.

As a carrier of carbon dioxide

3.

As a buffer of hydrogen ion.

This last effect is enhanced when oxyhemoglobin becomes dexygenated. This is due to conformational change in the protein exposing a larger number of sites (imidazole groups) that are capable of binding with hydrogen. This effect is called the Haldane Effect