Pancreatic secretions contain aqueous component (HCO3) and enzymatic component (to digest carbohydrates, proteins, and lipids). Formation of the pancreatic secretions takes place in the exocrine portion, acinar cells secrete the enzymatic component, while centroacinar and ductal cells secrete and modifies the aqueous component to finalize it as an isotonic secretion. The most important physiological factor to determine the pancreatic secretion is the flow rate. High flow rate results in high HCO3- and low Cl-, while Low flow rate results in Low HCO3- and high Cl- composition.