What is the primary form of carbon dioxide in the blood?

The primary form of carbon dioxide in the blood is bicarbonate. In the bloodstream, carbon dioxide is produced as a byproduct of metabolism and is primarily transported in the form of bicarbonate ions (HCO3-). This transformation occurs primarily in red blood cells, where carbon dioxide reacts with water to form carbonic acid, which then dissociates to produce bicarbonate and hydrogen ions.

Bicarbonate serves an important role in maintaining the pH balance of the blood through the bicarbonate buffer system. It is the most significant form of carbon dioxide transport, accounting for about 70% of the carbon dioxide carried in the blood.

While carbamino compounds are formed when carbon dioxide binds with proteins, and dissolved gas refers to the small amount of carbon dioxide that remains as a gas in the plasma, neither constitutes the primary method of transport for carbon dioxide in the body. Carboxyhemoglobin, which occurs when carbon monoxide binds to hemoglobin, is not relevant in this context, as it does not pertain to the transportation of carbon dioxide.