How much carbon dioxide is transported as carbaminohemoglobin (HbCO2)?

The transportation of carbon dioxide in the blood occurs through several mechanisms, and one significant pathway involves its binding to hemoglobin to form carbaminohemoglobin (HbCO2). Approximately 23% of the carbon dioxide in the blood is carried in this form. This occurs because carbon dioxide can bind directly to the amino groups of hemoglobin molecules, resulting in the formation of carbamino compounds.

When carbon dioxide enters the bloodstream, a part of it reacts with the amino acids in hemoglobin, facilitating its transport back to the lungs. This process is important for efficient gas exchange—allowing carbon dioxide to be removed from tissues and exhaled.

In contrast, the majority of carbon dioxide is transported either dissolved directly in plasma (around 7-10%) or as bicarbonate ions, which account for about 70% of carbon dioxide transport. Understanding these different forms of carbon dioxide transport is crucial in studying respiratory physiology and the mechanisms that keep our blood pH balanced during gas exchange.