One of the most important components 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. Given the importance of this complex of organs, it is necessary to protect it.
Consider what the
digestive system is, the functions
of the digestive system are also not disregarded. You will also learn about what must be done in order not to have gastrointestinal diseases.
What organs enter the digestive system?
The digestive system consists of the following organs and departments:
- the oral cavity with the salivary glands entering it;
- pharynx;
- esophagus area;
- stomach;
- small and large intestines;
- liver;
- pancreas.
Next, we will consider the structure and functions of the digestive system. The table below provides an overview of the components of the digestive tract.
| Body name | Anatomical features | Functions Performed |
| oral cavity | there are teeth and tongue for chopping food | analysis of incoming food, its grinding, softening and wetting with saliva |
| esophagus | membranes: serous, muscular, epithelium | motor, secretory, protective |
stomach | profuse artery and capillary artery bypass grafting | digestion of food |
| Duodenal ulcer | has ducts of the pancreas and liver | food promotion |
| liver | has blood supplying veins and arteries | distribution of nutrients; 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 | hinged, the walls may contract, there are villi on the inner surface | the implementation of abdominal and parietal digestion, absorption of degradation products |
| large intestine with a straight section and anus | walls have muscle fibers | digestion due to bacteria, absorption of water, stool, bowel movement |
If you look at the structure of this system of organs, it can be noted that the digestive tract is a tube with a length of 7-9 m. Some large glands are located outside the walls of the system and have a message 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, but 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 taking place in each of the digestive tract.
The general scheme of the digestive tract
The oral cavity, pharynx and esophagus are in fact in a direct direction.
Now let's briefly review the sequence of food passage through the digestive system. Nutrient components enter the human body through the mouth opening.
Next, the mass follows into the pharynx, in which the digestive tract and respiratory organs intersect. After this section, a food lump is sent down the esophagus. Chewed and moistened with saliva food enters the stomach. In the abdominal region are the organs of the final segment of the esophagus: the stomach, thin, blind, colon sections of the intestine, as well as the glands: liver and pancreas.
The rectum is located in the pelvic area. Food in the stomach cavity is at different times depending on the type of food, but this period does not exceed several hours. At this time, the so-called gastric juice is secreted into the cavity of the organ . Food becomes liquid, it mixes and digests. Moving further, the mass enters the small intestine. Here, the activity of enzymes ensures the further dissolution of nutrient substances to simple compounds, which are absorbed without difficulty into the bloodstream and lymph.
Further, the residual masses advance 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 into the environment through the anus.
Why does a person need saliva?
There are large and small salivary glands on the oral mucosa, with which the sequence of passage of food through the digestive system begins . Large are those located near the ears, 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 can only produce mucus. Salivation can be quite intense. For example, when drinking lemon juice, up to 7.5 ml per minute can stand out.
For the most part, saliva consists of water, but it contains enzymes: maltase and amylase. These enzymes start the digestion process already in the oral cavity: starch is converted by amylase to maltose, which is further cleaved by maltase 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 completely dissolve. Saliva usually has either a neutral or slightly alkaline reaction. Also in this liquid medium contains a special protein lysozyme, which has a bactericidal property.
Follow the esophagus
The anatomy of the digestive system calls the esophagus the next organ after the mouth and throat of the digestive tract. If we consider its wall in a section, then we can clearly distinguish three layers. The median is muscular and able to contract. This quality allows food to move from the throat to the stomach. The muscles of the esophagus produce wave-like contractions that spread from the upper part of the organ over its entire duration. When the food lump passes along this tube, the input sphincter opens into the stomach.
The specified muscle holds food in the stomach and prevents it from moving in the opposite direction. In some cases, the locking sphincter weakens, and the digested masses can be thrown into the esophagus. Reflux occurs, a person feels heartburn.
Stomach and Digestion Secrets
We continue to study the order 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 musculature of the wall.
The shape and size of the stomach directly depend on 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 already be 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, its mechanical and chemical processing occurs through the movement of muscles. Digested food advances to the small intestine.
From the inside, the stomach is lined with a mucous membrane with many folds in which the glands are located. Their task is to isolate as many digestive juices as possible. Gastric cells produce enzymes, hydrochloric acid and mucoid secretion. The food lump is impregnated with all these substances, crushed and mixed. The muscles, contracting, promote digestion.
What is gastric juice?
Gastric juice is a colorless liquid with an acid reaction, which is explained by the presence of hydrochloric acid. Three main groups of enzymes work in it:
- proteases (mainly pepsin) break down proteins into polypeptide molecules;
- lipases acting on fat molecules, turning them into fatty acids and glycerin (only emulsified fat of cow's milk is broken down in the stomach);
- salivary amylases continue to break down complex carbohydrates into simple sugars (as the lump is completely saturated with acidic gastric juice, amylolytic enzymes are inactivated).
Hydrochloric acid is a very important element of digestive secretion, since it activates the enzyme pepsin, prepares protein molecules for cleavage, curdls milk and neutralizes all microorganisms. The allocation of gastric juice occurs mainly when eating and lasts for 4-6 hours. In total, up to 2.5 liters are released per day.
An interesting fact is that the amount and composition of gastric juice depends on the quality of the incoming food. The greatest amount of secretion is allocated for the digestion of protein substances, the smallest - when a person absorbs fatty foods. In a healthy 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 enter 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 is the shortest and widest section, its length is about 30 cm;
- the skinny intestine is characterized by a decrease in clearance and a length of up to 2.5 m;
- The ileum is the narrowest part of the thin section, its length is up to 3.5 m.
The small intestine is located in the abdominal cavity in the form of loops. From the frontal part it is covered with an omentum, and on the sides it is limited by 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 thick section.
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, lymphatic and blood vessels;
- muscle tissue, which consists of the outer longitudinal and inner circular layers, and between them is a layer of connective tissue with nerves and vessels (the muscle layer is responsible for mixing and moving the digested food along the system);
- the serous membrane is smooth and moisturized, it prevents the friction of organs between themselves.
Features of digestion in the small intestine
The glands that make up the structure of intestinal tissue secrete a secret. It protects the mucosa from injury and from the activity of digestive enzymes. The mucous tissue forms many folds of circular orientation, and this increases the absorption area. The amount of these formations decreases towards the large intestine. From the inside, the mucosa of the small intestine is replete with villi and indentations that aid digestion.
In the 12-finger compartment, a slightly alkaline medium, however, with the contents of the stomach getting into it, the pH decreases. The pancreas has a duct in this zone, and its secret alkalizes the food lump, the environment of which becomes neutral at the same time. Thus, gastric juice enzymes are inactivated here.
A few words about the digestive glands
The digestive system of the organs has ducts of the endocrine glands. The pancreas secretes its juice as a person takes food, and its amount depends on the composition of the food. 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. 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 12th finger section, about half of the proteins and sugars that come with food are digested, as well as a small portion of the fat. In the small intestine, the enzymatic breakdown of organic compounds continues, but less intensively, and parietal absorption predominates. Most intensively, this process occurs after 1-2 hours from the moment of eating. It exceeds the effectiveness of a similar stage in the stomach.
Large intestine - the final digestive station
This section of the gastrointestinal tract is finite, its length is about 2 m. The names 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 in the descending colon. In this section of the digestive tract, the following zones are distinguished:
- cecum having a vermiform appendix, or appendix;
- ascending colon;
- transverse colon;
- descending colon;
- sigmoid colon;
- straight section ending with anus.
Overcooked food enters from the small intestine into the colon through a small hole in the form of a slit located horizontally. Here 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 digesting food lasts from one to three hours, then most of it is allocated to the lump in the large intestine. It contains the accumulation of contents, the implementation of the absorption of necessary substances and water, movement along the tract, the formation and removal of feces. The physiological norm is the intake of digested food in the colon 3-3.5 hours after the meal. This department is filled during the day, then it should be completely emptied in 48-72 hours.
In the large intestine, glucose, amino acids, vitamins and other substances are produced by bacteria living in this section, as well as the vast majority (95%) of water and various electrolytes.
Gastrointestinal inhabitants
Almost all organs and parts of the digestive system are inhabited by microorganisms. Only the stomach has relative sterility (on an empty stomach) due to the 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 thick 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 to humans;
- the 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 health!
Like any part of the human body, the digestive system of organs can be susceptible to various diseases. Often they are associated with the ingestion of pathogenic microorganisms from the outside. However, if a person is healthy 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 with a small one: poor nutrition, lack of rough fiber 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 organs is particularly susceptible to destructive influences from the outside. Therefore, do not forget to undergo a medical examination in a timely manner and consult a doctor in case of malfunctions in the normal functioning of the body.