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Gastrointestinal physiology is the branch of human physiology that addresses the physical function of the gastrointestinal (GI) tract.The function of the GI tract is to process ingested food by mechanical and chemical means, extract nutrients and excrete waste products.
The gastrointestinal tract (GI tract, digestive tract, alimentary canal) is the tract or passageway of the digestive system that leads from the mouth to the anus.The GI tract contains all the major organs of the digestive system, in humans and other animals, including the esophagus, stomach, and intestines.
The digestive system is supplied by the celiac artery. The celiac artery is the first major branch from the abdominal aorta, and is the only major artery that nourishes the digestive organs. There are three main divisions – the left gastric artery, the common hepatic artery and the splenic artery.
In most vertebrates, digestion is a multistage process in the digestive system, starting from ingestion of raw materials, most often other organisms. Ingestion usually involves some type of mechanical and chemical processing. Digestion is separated into four steps: Ingestion: placing food into the mouth (entry of food in the digestive system),
Digestive enzymes take part in the chemical process of digestion, which follows the mechanical process of digestion. Food consists of macromolecules of proteins, carbohydrates, and fats that need to be broken down chemically by digestive enzymes in the mouth , stomach , pancreas , and duodenum , before being able to be absorbed into the ...
Although a few similar compounds can be absorbed in digestion bio assimilation, the bioavailability of many compounds is dictated by this second process since both the liver and cellular secretions can be very specific in their metabolic action (see chirality). This second process is where the absorbed food reaches the cells via the liver.
Humans can consume a variety of carbohydrates, digestion breaks down complex carbohydrates into simple monomers (monosaccharides): glucose, fructose, mannose and galactose. After resorption in the gut , the monosaccharides are transported, through the portal vein , to the liver, where all non-glucose monosacharids (fructose, galactose) are ...
Intracellular digestion can also refer to the process in which animals that lack a digestive tract bring food items into the cell for the purposes of digestion for nutritional needs. This kind of intracellular digestion occurs in many unicellular protozoans, in Pycnogonida , in some molluscs , Cnidaria and Porifera .
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