Overview Pancreatic secretions overview exocrine pancreas releases secretions into duodenum of small intestine secretions contain aqueous and enzymatic components aqueous component contains HCO3- neutralizes H+ delivered to duodenum from stomach enzymatic component contains pancreatic enzymes digest carbohydrates, proteins, and lipids into absorbable molecules lipid digestion begins in the duodenum; however, lipid absoprtion occurs primarily in the jejunum formation of pancreatic secretions exocrine pancreas organization resembles that of salivary glands acinar cells secrete enzymatic components of pancreatic secretions see Pancreatic Enzymes centroacinar cells and ductal cells secrete initial isotonic aqueous components of pancreatic secretions ductal cells modify initial isotonic aqueous components by transport processes in ductal epithelial cells modification results in HCO3- release into pancreatic secretions and net absorption of H+ causes acidification of pancreatic blood pancreatic secretions remain isotonic flow rate and composition of pancreatic secretions flow rate changes HCO3- and Cl- concentrations in pancreatic secretions reciprocal relationship at highest flow rates high HCO3- and low Cl- at lowest flow rates low HCO3- and high Cl-