HCO3, or bicarbonate, is a chemical compound that plays a crucial role in maintaining the body's pH balance. It acts as a buffer, helping to neutralize acids in the bloodstream and keep the blood slightly alkaline. Bicarbonate is produced in the body, primarily by the pancreas, and is also obtained from dietary sources. In addition to its role in pH regulation, bicarbonate is important for various physiological processes, including respiration and digestion. It helps transport carbon dioxide from tissues to the lungs for exhalation. Abnormal levels of bicarbonate can indicate health issues, such as metabolic acidosis or alkalosis.