The digestive system provides human life through the delivery of necessary nutrients used as an energy source and building material. These substances enter the body through the digestive tract, the total length of which is about 10 meters and having throughout the expansion, cavity and narrowing.
The structure of the human digestive system includes: the oral cavity, pharynx, esophagus, stomach, pancreas, liver, gall bladder, large and small intestines.
Oral cavity. In this part of the digestive system, food is directly tested, subjecting it to chemical and physical effects. Chewing food refers to the second type of exposure, and the quality of nutrient intake and assimilation depends on this initial stage of the system . Not without reason, many experts advise chewing food as thoroughly as possible, which then forms under the influence of saliva into a food lump.
Saliva has a rather important role in the process of digesting food. It consists almost entirely of water (about 99%). The mucin protein contained in it promotes stickiness, the presence of lysozyme provides disinfection of food, and enzymes such as amylase and maltase break down nutrients.
The anatomy of the digestive system shows that the next organ behind the oral cavity is the pharynx, which is a muscular organ with certain openings (the oral opening, nasal entries, the entrances to the esophagus and larynx, and two tubes from the middle ear). To avoid food ingestion in the respiratory tract, the entrance to the larynx is covered by the epiglottis.
The process of swallowing food itself occurs due to contraction of the muscles of the pharynx, due to which it enters the esophagus and then through the diaphragm to the stomach. Since the esophagus is a muscle tube, food is pushed further by contracting these muscles.
The digestive system includes the stomach, which is located under the diaphragm in the upper abdominal cavity. By nature, it has two openings - an entrance and an exit. The second is closed by a sufficiently strong obstructive muscle (sphincter). Food lingers in the stomach for a long time (up to 11 hours), where it is chemically exposed to gastric juice, which is a colorless liquid containing hydrochloric acid. It is with the help of this component that the digestive function is directly performed. Acid also has a detrimental effect on bacteria entering the human body. Therefore, when diseases of the gastrointestinal tract occur, there is a risk of infection with infectious diseases that are transmitted through the digestive system.
The resulting food gruel from the stomach in portions through the sphincter gradually enters the intestine. The small intestine begins with the duodenum, into which the common bile duct and ducts of the pancreas open. Here, the digestion of food is completed under the action of pancreatic juice and bile.
From the small intestine, processed food gradually passes into the colon, which has a length of up to 2 meters. Here, water is intensively absorbed, and the remnants of unnecessary food are already excreted from the body. Due to the large number of different bacteria in the intestine, the absorption of food is improved. However, there are also negative points. So, under the influence of these microorganisms, the destruction of already unnecessary food products occurs, and poisonous compounds are formed, the elimination of which the liver is responsible for.
The digestive system gives the liver one of the leading roles. After all, this is the largest digestive gland through which all venous blood passes and cleanses from the stomach, spleen and intestines.
Thus, the digestive system is a rather complex system of food processing in the human body, each organ of which has a specific role, and if at least one component of this mechanism fails, diseases of the gastrointestinal tract can develop.