Digestive system of gastropods jaw structure can be ribbed or smooth: Some species have no jaw. Salivary glands plays primary role in the anatomical and physiological adaptations of the digestive system of predatory gastropods. Ducts from large salivary glands lead into the buccal cavity, and the oesophagus also supplies the digestive enzymes that help to break down the food. Salivary secretions lubricate the food and they also contain bioactive compounds. The mouth of gastropods opens into an oesophagus, which connects to the stomach. Because of torsion, the oesophagus usually passes around the stomach, and opens into its posterior portion, furthest from the mouth. In
Human digestive system the duodenum. (The enzymes that digest polysaccharides, by contrast, are primarily produced by the walls of the intestines.) The cells are filled with secretory granules containing the precursor digestive enzymes. The major proteases, the pancreatic enzymes which work on proteins, are trypsinogen and chymotrypsinogen. Elastase is also produced. Smaller amounts of lipase and amylase are secreted. The pancreas also secretes phospholipase A2, lysophospholipase, and cholesterol esterase. The precursor zymogens, are inactive variants of the enzymes; which avoids the onset of pancreatitis caused by autodegradation. Once released in the intestine, the enzyme enteropeptidase present in the intestinal mucosa activates trypsinogen by