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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.
Digestion is a form of catabolism that is often divided into two processes based on how food is broken down: mechanical and chemical digestion. The term mechanical digestion refers to the physical breakdown of large pieces of food into smaller pieces which can subsequently be accessed by digestive enzymes.
The cephalic phase of digestion is the stage in which the stomach responds to the mere sight, smell, taste, or thought of food. About 20% of total acid secretion occurs before food enters the stomach.
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.
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 ...
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.
However, the net energy derived from the macronutrients depends on such factors as absorption and digestive effort, which vary substantially from instance to instance. Vitamins, minerals, fiber, [9] and water do not provide energy, but are required for other reasons. A third class of dietary material, fiber (i.e., nondigestible material such as ...
Microvilli are present on the epithelium of a villus and further increase the surface area over which absorption can take place. Numerous intestinal glands as pocket-like invaginations are present in the underlying tissue. In the large intestines, villi are absent and a flat surface with thousands of glands is observed.