What are the major transport mechanisms for CO₂
? Explain.

Transportation of carbon dioxide : It is transported in three forms :

1. In solution form : About 7% CO₂ dissolves in plasma and is transported as such.

(2) Through RBCs: About 20 – 25% of CO₂ is transported by the red blood cells as  carbaminohaemoglobin. Carbon dioxide binds to the amino groups on the polypeptide chains of haemoglobin and forms a compound known as carbaminohaemoglobin.
(3) Through sodium bicarbonate: About 70% of carbon dioxide is transported as sodium bicarbonate. As CO₂ diffuses into the blood plasma, a large part of it combines with water to form carbonic acid in the presence of the enzyme carbonic anhydrase. Carbonic anhydrase is a zinc enzyme that speeds up the formation of carbonic acid. This carbonic acid dissociates into bicarbonate (HCO3^–) and hydrogen ions (H⁺).