Consider the physiology of digestion, or what happens to food in the gastrointestinal tract during digestion, as our body of pizza, soup or compote takes those substances which are necessary for his work.
Understanding the physiology of digestion
The main purpose of the gastrointestinal tract - the transformation of food into such a molecule that can be absorbed into the bloodstream and transported to other organs. These processes begin with a mechanical food processing and secretion of digestive juices. They contain the enzymes break down proteins, fats and carbohydrates into smaller fragments that can be absorbed (digestion). Along with water, mineral salts and vitamins, the end products of digestion enter the blood and lymph through the cells of the intestinal mucosa (absorption).
The gastrointestinal tract is a solid receiver and a member of the oral cavity, pharynx, esophagus, stomach, small and large intestines. There comes secreta several organs: salivary glands, pancreas and liver. The walls of the digestive tube in its entirety are based on a single plan, although its different departments have different functions. Some sections of the gastrointestinal tract (oral cavity and esophagus) are used primarily for transportation of food, while others (the stomach and small intestine) - to store it, and some (small intestine) - for the digestion and absorption.
The complex regulation of these functions is carried out in several ways: 1) through a variety of hormones and bioactive peptides (specific proteins), 2) due to contraction of muscle cells (please note that visceral muscle cell specific - the so-called smooth muscle), 3) the autonomic nervous system (this is a special nervous system, which are under the control of internal organs and is not amenable to control our minds.) Violation of the normal function of the digestive tract can lead to various diseases and manifestations (diarrhea, constipation, vomiting, heartburn, colic, etc.).
Regulation. In addition to the regulation from the outside (the autonomic nervous system: the vagus nerve and sympathetic nerve fibers) in the gastrointestinal tract has its own, internal nervous system - "intestinal brain" that operates independently and regulates motor (motor) and secretory (isolation of biologically active substances) function of the stomach and intestines.
Hormones. The gastrointestinal tract refers to the organs most susceptible to hormonal influences. To date (1996) in the mucosa of the gastrointestinal tract and pancreas revealed 18 types of cells that produce hormones (gastrin, secretin, cholecystokinin, etc.) and peptides. Moreover, production of these hormones depends not only on external regulation, but also on the direct effect of food components with themselves produce hormones and peptides by cells of digestive tract.
Motility. Digestion and absorption in the gastrointestinal tract is largely dependent on changes in the configuration of its walls, associated with the contraction and relaxation of muscles. These changes contribute to the promotion of food (and in a certain direction - from oral to anal opening), mixing it with digestive juices. When the stomach and small intestine dry out leftover food in the digestive tract is a characteristic phenomenon - the rhythmic "hungry" to reduce (we clearly feel them when hungry). Digestive juices are actively produced in the special (secretory) cells of various organs: both the stomach and intestines, and salivary glands and pancreas. Secreted by these cells is the secret of a solution containing mineral salts, enzymes and other proteins.
Immune system. Together with the components of food in the digestive tract gets a lot of bacteria, viruses, and food allergens (substances that can cause allergic reactions). To protect against gastro-intestinal tract has its own immune system is composed of specialized cells (lymphocytes, plasma cells) and their entire clusters (Peyer's patches). Normally, this barrier provides sufficient protection, but with infectious diseases of the intestine or due to other harmful factors can deteriorate.
Flatulence. Normally, the gastrointestinal tract contains at least 200 ml of gases. But when using a large amount of cellulose (foods rich in fiber) amount of gas can be considerably increased, since cellulose is split by bacteria in the colon, which normally live in the digestive tract. By eating beans, the number of gases can be increased by 10 times! This man feels "bloating" - a sense of fullness in the abdomen