Numerous hormones secreted by the digestive tract control smooth muscle activity and secretions in the digestive tract. For example, the hormone gastrin is secreted by the stomach when peptides and amino acids are present in the chyme. This results in in-creased gastric secretion and motility. Similarly, the arrival of lipids and carbohydrates in the duodenum stimulates secretion of the hormone cholecys-tokinin (CCK) and gastric inhibitory peptide (GIP).Both hormones slow the motility of the stomach and gastric secretion to allow more time for lipids to be digested and absorbed in the intestines. Many such hormones have been identified in the digestive tract. Please refer to more advanced textbooks for details.