Digestive system of gastropods the food forward in a steady stream from the mouth. Usually, the food is embedded in a string of mucus produced in the mouth, creating a coiled conical mass in the style sac. This action, rather than muscular peristalsis, is responsible for the movement of food through the gastropod digestive tract. Two diverticular glands open into the stomach, and secrete enzymes that help to break down the food. In the more primitive species, these glands may also absorb the food particles directly and digest them intracellularly. The hepatopancreas is the largest organ in stylommatophoran gastropods. It produces enzymes, and absorbs
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