What is digestive system?

What Does digestive system Mean

The ordered set of interrelated elements that develop interactions with each other is called a system . Digestive , on the other hand, is that linked to digestion (the process of digesting: transforming food into substances that the body can assimilate).

The digestive system , in this way, is the group of organs that intervenes in the digestion of food . These organs act from the entry of food into the body until its expulsion, taking care of the necessary treatment to complete the process that includes the absorption of nutrients .
The functioning and components of the human digestive system are described below, since in other species it presents certain differences, which can be slight or considerable.

It can be said that the digestive system is responsible for transporting food ; segregate juices that allow it to be broken down into simpler units; absorb nutrients; and excrete waste .
Food enters through the mouth , passes through the pharynx and esophagus , reaches the stomach , passes into the small intestine and finally up to the large intestine . In this journey through the digestive system, various substances act.
It all starts in the mouth, when we put a piece of food inside. The teeth allow the food to be crushed, while the saliva begins the process of formation of the food bolus, which passes through the pharynx and esophagus until it reaches the stomach, where muscle movements and gastric juice contribute to its transformation into the chyme . The process continues in the small intestine, with the action of pancreatic juices and bile . Finally, digestion is completed in the large intestine, whose final section is known as the rectum : the anus is located in it , where the remains are expelled of foods that cannot be digested.
From a histological point of view, that is, taking into account the structure, composition and characteristics of its organic tissues, the digestive system is made up of the following four layers , in this case ordered from the center outwards:
* mucous layer : it is also known as the inner layer , and in it it is possible to find glands that secrete hydrogen chloride and mucus, certain lymphoid nodules and lymphatic vessels. It also has an internal muscular layer (whose scientific name is muscularis mucosae ), which in turn is made up of two others, an internal circular and an external longitudinal smooth muscle layer ;

* Submucosa layer : it is composed of connective tissue of a dense irregular fibroelastic type. It is the so - called submucosal plexus of Meissner , which is part of the enteric nervous system and is responsible for controlling the submucosa, secretion of the glands and to a greater extent, motility (the ability to move so coordinated and complex) of the mucosa;
* External muscular layer : in the same way as the muscularis mucosae , it is composed of a circular inner layer and a longitudinal outer layer of smooth muscle, with the exception of the esophagus, in which we find striated muscle. Its main function is to perform peristaltic movements for the displacement of the lumen content throughout the digestive tract. For its regulation it relies on Auerbach's myenteric plexus , which is part of the enteric nervous system;
* adventitial or serous layer : in this case, each name is applied according to the part of the digestive tract that is in charge of covering. If it is intraperitoneal , it is called serous, while if it is retroperitoneal it is called adventitia. The former is seen in the part of the digestive tract that enters the abdomen , while the latter presents a loose tissue and at the end of its journey it is replaced by the peritoneum.

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