Describe the carriage of carbon dioxide (CO2) in the blood.

[Click here to toggle visibility of the answers]

College Answer

A definition of arterial and venous CO2 content (mls and partial pressure) and an outline of the 3 forms of CO2 in the blood and their contribution to the AV difference, followed by a detailed explanation of each form of carriage was required for this question. A good answer included a table of the contribution of each form of carriage to arterial and venous content and the AV difference; explained the concepts of chloride shift when describing carriage as HCO3 - ; detailed the Haldane effect and its contribution to carbamino carriage and referenced Henry’s law when describing dissolved CO2.

West’s Chapter 6 on gas transport details the key information to score well on this question.

Discussion