The main function of the gastrointestinal tract is preparing food for living cells, the secretion of bile from the liver restriction and expenditure leftover food that is not digested. This function requires a variety of diverse physiological processes of digestion, the digestive activity can be either: (Sommers, 1994; Noerasid, 1999 cit Sinthamurniwaty 2006)
The process of entry of food from the mouth into the intestine.
The process of chewing (mastication): smoothing the food chewing and mixing with enzymes in the oral cavity.
The process of swallowing food (diglution): the movement of food from the mouth to the stomach.
Digestion: mechanical destruction of food, food ingredients mixing and hydrolysis by enzymes.
Food absorption (absorption): food molecules traveling through the mucous membranes of the intestines into the blood and lymph circulation.
Peristalsis: rhythmic movements of the intestinal wall in the form of a wave of contraction that moves food from the stomach to the distal.
Bowel movements (defecation): disposal of food waste in the form of feces.
Under normal circumstances where the effective functioning digestive tract will produce as much fecal residues 50-100 grams a day and water containing as much as 60-80%. In the gastrointestinal tract, fluid passively following movement of bidirectional transmucosal or longitudinal intraluminal with solid electrolytes and other substances that have active osmotic properties. The fluid that was in the gastrointestinal tract consists of the incoming fluid by mouth, saliva, gastric secretions, bile, pancreatic secretions and intestinal secretions smooth. The liquid is absorbed by the small intestine, and large intestine reabsorbs subsequent intestinal fluid, so that the remaining approximately 50-100 g as a stool.
Motility of the small intestine has the function to:
- Regularly move the bolus of food from the stomach to the cecum.
- Mix chyme with pancreatic enzymes and bile.
- Prevent bacteria to breed.