TOPICS: Alpha-amylase, R protein, vitamin B12, bolus, peristalsis, lower esophageal sphincter (LES), oral cavity, esophagus, stomach, small intestine, large intestine, gastric cells, parietal cells, intrinsic factor, chief cells, pepsinogen, pepsin, protein metabolism, protein digestion, mucous cells, G cells, gastrin, D cells, somatostatin, stem cells, gastric pits, ileum, duodenum, primary active transport, cephalic phase of acid secretion, vagus nerve, gastric phase of acid secretion, histamine, intestinal phase of acid secretion, peptide YY, enterochromaffin-like cells (ECLs), prostaglandin E (PGE), mucus barrier, folate, vitamin K, diverticula