The digestive systemís primary function is to convert food into energy and convert waste into excretable material. The digestive tract and its accompanying digestive organs are responsible for the absorption and digestion of all digestible products. The digestive system sustains life via its ability to relieve the body of its inability to provide nutrients for its systems, tissue, and bodily fluids. Without the digestive system, all other systems would eventually fail to operate, fluids would either stop production or dry up, and tissue would deteriorate.
Digestible product is utilized at the cellular level, which the digestive system readily prepares for cellular use. Nutrients from food or other nutritious edible product are broken down and the remaining nutrients are used for chemical reactions which allow cells throughout the body to reproduce, repair, cellular division, cellular growth, heat production, energy production, and the synthesis of enzymes which allow these functions to occur.
Food which is consumed by a human can not be used for cellular health until after it has been broken down both mechanically and chemically for the use of meeting cellular needs. The broken down and digested foods turn into nutrients which are then absorbed through the intestinal wall. The nutrients are then transferred to the cells via the blood stream and delivered to the site of cells which are in need of the nutrients. Food is not considered to be digested until after absorption, which applies to a small percentage of food as most of the food eaten is never absorbed and is passed through the excretory system. Only usable nutrients and chemicals are absorbed and brought to the appropriate cellular group for nutritional function.
Ingestion is the process of eating. In reference to the digestive system, this typically means food however it may include vitamin supplements, medications, and liquids.
Mastication is the process of mixing edible elements with saliva for the purposes of breaking the edible elements down. This process typically involves chewing.
Deglutition refers to the process of moving edible elements from the mouth down through the esophagus and into the stomach. Digestion is the process of breaking down the edible elements and preparing them for absorption through the intestinal wall and use by the cells.
Absorption refers to the process of passing the broken down edible elements through the intestinal wall into the blood stream where either blood cells or lymph cells retrieve the nutrients and carry them off toward their destination.
Peristalsis is the action of processing waste, referring in particularly to the motion made by the intestinal tract which resembles wave-like motions to help pass the solid waste through the intestines.
Defecation is the final process in the digestive system which removes solid waste product in the form of fecal matter from the body.
The digestive system is generally divided into specific functional and anatomical groups that consist of the digestive tract, the tubular gastrointestinal tract, and the accessory digestive organs. The tubular gastrointestinal tract is one continuous tract, shaped for the most part in a cylinder that runs from the mouth to the anus creating a pathway for food, nutrients, and waste. At 30 feet long, it traverses the thoracic cavity and enters the abdominal cavity along the diaphragm and includes the oral cavity, thorax, esophagus, stomach, small intestines, and large intestines. The accessory digestive organs, those which are vital to the process but can not otherwise be classified, include the teeth, tongue, liver, salivary glands, pancreas, and gallbladder.
Visceral organs were once meant to include the internal organs of the digestive tract which were related to digestion. However over time visceral organs became known as any internal organ that is relative to the thoracic cavity or the abdominal cavity.
Anywhere from 24 to 48 hours are likely to pass before food travels through the entire digestive tract. The breakdown of edible material and therefore the breakdown of molecules with vital value to the bodyís cells, is done in the bodyís own version of an assembly line. Nutritional value is removed from the food on a molecular level and brought to the bodyís cells for nutritional absorption.