Human digestive system Human digestive system The human digestive system consists of the gastrointestinal tract plus the accessory organs of digestion (the tongue, salivary glands, pancreas, liver, and gallbladder). Digestion involves the breakdown of food into smaller and smaller components, until they can be absorbed and assimilated into the body. The process of digestion has many stages. The first stage is the cephalic phase of digestion which begins with gastric secretions in response to the sight and smell of food. The next stage starts in the mouth. Chewing, in which food is mixed with saliva, begins the mechanical process of digestion. This produces
Digestive system of gastropods Digestive system of gastropods The digestive system of gastropods (slugs and snails of every kind) has evolved to suit almost every kind of diet and feeding behavior. Gastropods as the largest taxonomic class of the mollusca are very diverse indeed: the group includes carnivores, herbivores, scavengers, filter feeders, and even parasites. In particular, the radula is often highly adapted to the specific diet of the various group of gastropods. Another distinctive feature of the digestive tract is that, along with the rest of the visceral mass, it has undergone torsion, twisting around through 180 degrees during the larval stage, so