One of the most important parts of the human body is its digestive system. This set is thought out and organized by nature in such a way that its owner can extract from the food consumed everything that is necessary for the implementation of normal life. And at the same time, such "magic" mechanisms work in the digestive system that protect us from infections, neutralize poisons and even allow us to synthesize important vitamins on our own. Considering the importance of this complex of organs, it is necessary to protect it.
Let's consider what the digestive system is, let's not disregard the functions of the digestive organs. You will also learn about what must be done in order not to have gastrointestinal diseases.
What organs are in the digestive system?
The digestive system consists of the following organs and departments:
- oral cavity with salivary glands included in it;
- throat;
- esophagus area;
- stomach;
- small and large intestine;
- liver;
- pancreas.
Next, we will consider the structure and functions of the organs of the digestive system. The table below gives a general idea of the constituent parts of the gastrointestinal tract.
| Name of authority | Anatomical features | Performed functions |
| oral cavity | has teeth and a tongue for grinding food | analysis of incoming food, its grinding, softening and wetting with saliva |
| esophagus | shells: serous, muscular, epithelium | motor, secretory, protective |
|
stomach |
abundant shunting of arteries and capillaries of blood vessels | digesting food |
| 12 duodenum | has pancreatic and liver ducts | food promotion |
| liver | has blood supplying veins and arteries | nutrient distribution; synthesis of glycogen, hormones, vitamins; neutralization of toxins; bile production |
| pancreas | located under the stomach | secretion with enzymes that break down proteins, fats and sugars |
| small intestine | stacked in loops, walls can shrink, there are villi on the inner surface | implementation of cavitary and parietal digestion, absorption of cleavage products of substances |
| thickintestine with straight section and anus | the walls have muscle fibers | completion of digestion by bacteria, absorption of water, formation of feces, bowel movements |
If you look at the structure of this organ system, it can be noted that the digestive tract is a tube 7-9 m long. Some large glands are located outside the walls of the system and communicate with it.
The peculiarity of this set of organs is that they are stacked very compactly. The length of the tract from the mouth to the anus is up to 900 cm, however, the ability of the muscles of the digestive tract to form loops and bends helped to fit them in the human body. However, our task is not only to list the organs of the digestive system. We will carefully study all the processes occurring in each of the gastrointestinal tract.
General scheme of the digestive tract
The mouth, pharynx and esophagus have a virtually straight direction.
Now let's take a quick look at the sequence of passage of food through the organs of the digestive system. Nutrient components enter the human body through the mouth.
Further, the mass goes into the throat, where the digestive tract and respiratory organs intersect. After this section, the food bolus is sent down the esophagus. The chewed and saliva-moistened food enters the stomach. In the abdominal region are the organs of the final segment of the esophagus: stomach, thin, blind, colonsections of the intestines, as well as glands: liver and pancreas.
In the pelvis is the rectum. Food in the cavity of the stomach is different time depending on the type of food, but this period does not exceed a few hours. At this time, the so-called gastric juice is released into the cavity of the organ. Food becomes liquid, it is mixed and digested. Moving further, the mass enters the small intestine. Here, the activity of enzymes ensures the further dissolution of nutrients to simple compounds that are easily absorbed into the bloodstream and lymph.
Further, the residual masses move into the large intestine, where water is absorbed and feces are formed. In fact, these are substances that are not digested and cannot be absorbed into the blood and lymph. They are removed to the external environment through the anus.
Why does a person saliva?
On the oral mucosa, which begins the sequence of passage of food through the organs of the digestive system, there are large and small salivary glands. Large are those that are located near the auricles, under the jaws and under the tongue. The last two types of salivary glands produce a mixed secret: they secrete both saliva and water. The glands near the ears are capable of producing only mucus. Salivation can be quite intense. For example, drinking lemon juice can release up to 7.5 ml per minute.
Saliva is mostly water, but it contains enzymes: m altase and amylase. These enzymes start the process of digestion already inoral cavity: starch is converted by amylase to m altose, which is further broken down by m altase to glucose. Food is in the mouth for a short time - no more than 20 seconds, and during this time the starch simply does not have time to dissolve completely. Saliva is usually either neutral or slightly alkaline. This liquid medium also contains a special protein, lysozyme, which has a bactericidal property.
Following the esophagus
Anatomy of the digestive system organs calls the esophagus the organ of the gastrointestinal tract following the mouth and pharynx. If we consider its wall in section, we can clearly distinguish three layers. The median is muscular and is able to contract. This quality allows food to move from the pharynx to the stomach. The muscles of the esophagus produce undulating contractions that spread from the top of the organ throughout its duration. When the food bolus passes along this tube, the inlet sphincter opens into the stomach.
This muscle holds food in the stomach and prevents it from moving in the opposite direction. In some cases, the locking sphincter weakens, and digested masses can be thrown into the esophagus. Reflux occurs, the person feels heartburn.
The stomach and the secrets of digestion
We continue to study the order of the organs of the digestive system. The esophagus is followed by the stomach. Its localization is the left hypochondrium in the epigastric region. This organ is nothing more than an extension of the digestive tract with pronounced wall musculature.
Shape andThe size of the stomach is directly related to its contents. An empty organ has a length of up to 20 cm, the distance between the walls is 7-8 cm. If the stomach is moderately filled, then its length will become about 25 cm, and its width will be up to 12 cm. The capacity of the organ can also vary depending on the degree of its fullness and varies from 1.5 liters to 4 liters. When a person swallows, the muscles of the stomach relax, and this effect lasts until the end of the meal. But even when the meal is over, the muscles of the stomach are in a state of activity. Food is ground, it is mechanically and chemically processed through muscle movement. Digested food moves to the small intestine.
The inside of the stomach is lined with a mucous membrane with many folds in which the glands are located. Their task is to secrete as many digestive juices as possible. Cells of the stomach produce enzymes, hydrochloric acid and mucoid secretion. The food lump is impregnated with all these substances, crushed and mixed. Muscles contract to aid digestion.
What is gastric juice?
Gastric juice is a colorless liquid with an acidic reaction due to the presence of hydrochloric acid. It contains three main groups of enzymes:
- proteases (mainly pepsin) break down proteins into polypeptide molecules;
- lipases that act on fat molecules, turning them into fatty acids and glycerol (only emulsified cow's milk fat is broken down in the stomach);
- saliva amylase continue to work onbreakdown of complex carbohydrates into simple sugars (as the food bolus is completely saturated with acidic gastric juice, amylolytic enzymes are inactivated).
Hydrochloric acid is a very important element of the digestive secretion, as it activates the enzyme pepsin, prepares protein molecules for breakdown, curdles milk and neutralizes all microorganisms. The secretion of gastric juice occurs mainly when eating and continues for 4-6 hours. In total, up to 2.5 liters of this liquid is released per day.
An interesting fact is that the amount and composition of gastric juice depend on the quality of the incoming food. The largest amount of secretion is released for the digestion of protein substances, the smallest - when a person absorbs fatty foods. In a he althy body, gastric juice contains a fairly large amount of hydrochloric acid, its pH ranges from 1.5-1.8.
Small intestine
When studying the question of which organs are included in the digestive system, the further object of study is the small intestine. This section of the digestive system originates from the gastric pylorus and has a total length of up to 6 meters. It is divided into several sections:
- The duodenum 12 is the shortest and widest section, its length is about 30 cm;
- skinny intestine is characterized by a decrease in lumen and a length of up to 2.5 m;
- the ileum is the narrowest part of the thin section, its lengthis up to 3.5 m.
The small intestine is located in the abdominal cavity in the form of loops. From the front, it is covered with an omentum, and on the sides it is limited to a thick digestive tract. The function of the small intestine is the continuation of the chemical transformations of food components, its mixing and further direction to the large intestine.
The wall of this organ has a typical structure for all components of the gastrointestinal tract and consists of the following elements:
- mucosal layer;
- submucosal tissue with accumulations of nerves, glands, lymphatics and blood vessels;
- muscle tissue, which consists of outer longitudinal and inner circular layers, and between them is a layer of connective tissue with nerves and blood vessels (the muscle layer is responsible for mixing and moving digested food along the system);
- The serosa is smooth and hydrated, preventing the organs from rubbing against each other.
Features of digestion in the small intestine
The glands that make up the structure of the intestinal tissue secrete a secret. It protects the mucosa from injury and from the activity of digestive enzymes. Mucous tissue forms many circular folds, and this increases the suction area. The number of these formations decreases towards the large intestine. From the inside, the lining of the small intestine is replete with villi and depressions that help digestion.
The duodenal region is slightly alkaline, but with the ingestion of stomach contents, the pH decreases. The pancreas has a ductthis zone, and its secret is alkalized by a food lump, the environment of which becomes neutral. Thus, the enzymes of the gastric juice are inactivated here.
A few words about the digestive glands
The digestive system of organs has ducts of endocrine glands. The pancreas secretes its juice as a person eats, and its amount depends on the composition of the food. A protein diet provokes the greatest secretion, and fats cause the opposite effect. In just a day, the pancreas produces up to 2.5 liters of juice.
Also, the gallbladder secretes its secret into the small intestine. Already 5 minutes after the start of the meal, bile begins to be actively produced, which activates all the enzymes of the intestinal juice. This secret also enhances the motor functions of the gastrointestinal tract, intensifies the mixing and movement of food. In the 12-duodenal section, about half of the proteins and sugars that come with food, as well as a small part of the fats, are digested. In the small intestine, the enzymatic decomposition of organic compounds continues, but less intensively, and parietal absorption predominates. This process occurs most intensively after 1-2 hours from the moment of eating. It is more effective than the same stage in the stomach.
The large intestine is the end station of digestion
This section of the gastrointestinal tract is final, its length is about 2 m. The names of the organs of the digestive system take into account their anatomical features, and it is logically clear that this section has the largest clearance. The width of the large intestine decreases from 7 to 4 cm at the descending colon. In this section of the digestive tract, the following zones are distinguished:
- caecum with appendix or appendix;
- ascending colon;
- transverse colon;
- descending colon;
- sigmoid colon;
- straight section ending in anus.
The digested food passes from the small intestine into the large intestine through a small hole in the form of a slot located horizontally. There is a kind of valve with a sphincter in the form of lips, which prevents the contents of the blind section from entering in the opposite direction.
What processes occur in the large intestine?
If the whole process of digestion of food lasts from one to three hours, then most of it is given to the lump in the large intestine. It accumulates contents, absorbs necessary substances and water, moves along the tract, forms and removes feces. The physiological norm is the intake of digested food in the large intestine 3-3.5 hours after the meal. This section is filled during the day, followed by its complete emptying in 48-72 hours.
The large intestine absorbs glucose, amino acids, vitamins and other substances produced by bacteria living in this section, as well as the vast majority (95%) of water and various electrolytes.
Inhabitants of the digestive tract
Practically all organs and parts of the digestive system are inhabited by microorganisms. Only the stomach is relatively sterile (on an empty stomach) due to its acidic environment. The largest number of bacteria is in the large intestine - up to 10 billion / 1 g of feces. The normal microflora of the large gastrointestinal tract is called eubiosis and plays a huge role in human life:
- prevents the development of pathogenic microorganisms;
- synthesis of B and K vitamins, enzymes, hormones and other substances useful for humans;
- breakdown of cellulose, hemicellulose and pectins.
The quality and quantity of microflora in each person is unique and is regulated by both external and internal factors.
Take care of your he alth
Like any part of the human body, the digestive system of organs can be prone to various diseases. Often they are associated with the ingress of pathogenic microorganisms from outside. However, if a person is he althy and his stomach works without failures, then all harmful bacteria are doomed to death in an acidic environment. If for a number of reasons this organ functions abnormally, then almost any infection can develop and lead to serious consequences, such as cancer of the digestive system. It all starts small: irrational nutrition, lack of rough fibrous foods in the diet, alcohol and fatty foods, smoking, stress, unbalanced diets, poor ecology and other adverse factors gradually destroy our body and provoke the development of diseases.
The digestive system of the organs is especially susceptible to destructive external influences. Therefore, do not forget to undergo medical examinations in a timely manner and consult a doctor in case of malfunctions in the normal functioning of the body.
