What role does bicarbonate play in the blood?

Bicarbonate plays a crucial role in the regulation of acid-base balance in the blood, and one of its primary functions is to facilitate the transport of carbon dioxide (CO2) from tissues to the lungs. In the body, CO2 is produced as a byproduct of metabolism, and it is converted into bicarbonate ions (HCO3-) in red blood cells. This conversion is vital for maintaining pH balance in the blood.

When CO2 enters the bloodstream, it reacts with water to form carbonic acid (H2CO3), which quickly dissociates into bicarbonate and hydrogen ions. Most of the CO2 in the blood is transported in this bicarbonate form. When the blood reaches the lungs, the process is reversed; bicarbonate ions can combine with hydrogen ions to form carbonic acid, which then dissociates back to CO2 and water for exhalation.

This bicarbonate buffering system is essential to prevent acidosis or alkalosis, thus ensuring proper physiological function and maintaining homeostasis. The other options do not accurately represent the primary role of bicarbonate in the blood.