Gastrointestinal tract of man

The digestive system in humans performs a difficult job. It is sometimes completely unrelated to the processing and assimilation of food. One of the components is the gastrointestinal tract( GIT).It can be represented in the form of a path that passes food after eating. The structure of the gastrointestinal tract determines in many ways the propensity of the organism to a certain pathology.

Disease is not always organic( anatomical) disorders. Dysfunction of different parts of the human intestinal tract plays an important role in the occurrence of diseases. To find out the cause of the disease, it is necessary to take into account the anatomical and physiological features and connections of organs, the role of the nervous and hormonal systems in controlling the digestive process.

Why do I need a digestive system?

The digestive system performs the following main functions:

• motor - disintegration, mixing and movement of food masses along the path, excretion of toxins from the body;
• secretory - the synthesis of enzymes for processing the food lump to substances that allow it to absorb through the intestinal wall;
• suction - of all substances formed as a result of the cleavage, only the beneficial to the body are selected, water is absorbed.

Scientists have proved another, equally important role of the digestive tract - the development of antibodies for local immunity and active biological substances involved in systemic protection of humans. Gastrointestinal tract, as an important part of the structure of the digestive system is involved in each of these processes. Determine that the body is more important than the liver, pancreas or intestine is impossible. Because changes in any part entail a failure of the work of all components of the digestive tract.

Which experts study the work of the tract?

The structure of the human gastrointestinal tract is studied by the science of "Human Anatomy".From it, histology( studying the structure of tissues under a microscope), cytology( the main subject - the structure of the cell), physiology( reveals the mechanisms of work and functional connections of organs), and others "budged off".

The emergence and course of pathological processes refers to the field of patanatomy and pathophysiology. It was these previously unknown scientific disciplines that served as the basis for all clinical clinical specialties, and became the founders of many research directions in medicine. What is the gastrointestinal tract and how does it work?

The gastrointestinal tract can be represented schematically in the form of a "tube" that begins in the oral cavity and ends in the area of ​​the anal opening. In this structure there are departments of the digestive tract, each of which is responsible for certain tasks. In order to understand, because of which disorders there are diseases, we "walk along with food" along the tract and check which functions of the digestive tract are assigned to each department.

The better the food is chewed, the more readily it gets into the stomach, the saliva disinfects the food, protecting the underlying parts of the

system. The oral cavity of the

. In the mouth, the food is met with teeth that crush it to small pieces, saliva( the secret of large and small glands)language. Saliva enzymes break down the starchy substances in products, as a liquid, it moistens and facilitates swallowing. Long chewing can deceive the center of hunger and cause a sense of satiety, so it is recommended that the patient be obese to fight excessive weight.

The absence of teeth in the elderly, the problems of prosthetics significantly complicate the process. In a hurry, a person swallows unprepared to digest food pieces, which threatens a functional failure of the next stage in the stomach. Language receptors determine and transmit information about the amount and composition of enzymes that will be required for digestion.

Esophagus

Actually provides delivery of the food mass to the stomach due to longitudinal and transverse contractions of the muscular layer. The further process is localized below the diaphragm, in the cavity of the abdomen. Violation of the act of ingestion in case of structural anomalies or inflammation( achalasia, esophagitis) leads to a delay and stagnation of the lump. Delayed intake of food in the stomach affects the activity of the glands of its inner shell.

Stomach

Stomach has an elastic folded structure, it allows it to expand considerably. If necessary, the body can contain up to 4 liters of liquid and food. Not all products are processed equally quickly: glucose, alcohol, salt, water are first absorbed into the bloodstream. The gastric juice acts on the food residue. Active substances in it are mucus, hydrochloric acid, enzymes( pepsin, gastrin).

The lining of cells is between the epithelial cells. It is produced by the type of food, the smell. The maximum expenditure is spent on the processing of meat and spicy dishes. Changes in the form of atrophy disrupt the functioning of the organ.

Acidity decreases as it approaches the passageway to the duodenum

Duodenum

The duodenum is the initial part of the intestinal tract of a person. Its task is to obtain from the pylorus the stomach of the edible mass, the conversion of the acidic reaction into an alkaline reaction( more suitable for the intestine), and the continuation of the breakdown of proteins and carbohydrates. From the duodenum absorbed into the blood mineral substances, vitamins, excess fluid.

At this stage, the synthesized secret of the pancreas and bile are connected to digestion by attaching ducts through the common sphincter of Oddi.

Bile is produced by hepatocytes( hepatic cells), collected in a bladder, contains, in addition to water, fatty acids, cholesterol and inorganic substances.

The composition allows emulsifying fatty components of food, splitting them to amino acids, fatty acids, vitamins, and prevents decay processes. Through the pancreatic duct, pancreatic juice enters, containing more than 20 enzymes that affect all components of the food. The final digestion process occurs in the loops of the small and large intestine.

Intake of the pancreatic and bile duct

Intestine

The length of the small intestine is up to 6 m. In addition to the duodenum, it includes the jejunum and ileum. The wall must ensure absorption of the necessary substances into the blood vessels. For this, it is covered from the inside by folds and tiny villi. Large molecules do not pass through a dense shell.

There are about 200 species of bacteria in the intestine. The maximum amount is useful bifido- and lactobacilli. The remaining conditionally pathogenic in norm are 1-2% of the structure. Maintaining the right composition of the intestinal flora is very important for digestion. It is these smallest microorganisms, together with intestinal juice, that ensure the cleavage of food residues to molecules to be absorbed( amino acids, polysaccharides, fatty acids).

Infringement of the balance of microflora is sensitive to the effects of various factors, of which special attention is paid to medicinal substances( antibiotics).Therefore, after treatment of the gastrointestinal tract with antibacterial drugs, it is necessary to restore the necessary ratio of bacteria.

All substances from the intestine do not enter the general bloodstream, but into the portal vein of the liver. The fact is that in the form in which they are present in the intestine, chemicals can cause a fatal outcome, since they form poisons, toxins. The liver disinfects poisons to nontoxic compounds. The ileum "transfers" the remains of food to the large intestine.

It has a length of up to 2 m, anatomically divided into a cecum with appendicular process, ascending, transversal, descending, sigmoid, straight. The task of this department is the formation of stools, the completion of water absorption, the release of all accumulated slags from the body. Cells secrete mucus. Living bacteria help to destroy an alien infection, maintain immunity.

Cleansing function of the intestine depends on the work of the muscles. Their peristaltic movements allow transportation of feces to the area of ​​sphincters of the anus and are responsible for the act of defecation. The contractions depend on the interaction with the branches of the parasympathetic nervous system, the sufficient production of the mediator of acetylcholine.

The intestinal atony is a serious problem of postoperative and senile disorders. Stagnant slag causes an intoxication of the body, an allergic mood. These important departments are interconnected by a single process of digestion. Pathological changes in one of the levels lead to dysfunction of the entire gastrointestinal tract.

Blood is collected through the mesenteric vessels into the portal system of the liver

What do "functional diseases" mean?

Gastrointestinal departments do not work in isolation "on their own".They are associated with the management of the nervous system and the endocrine organs that release hormones. In addition, substances synthesized by the cells of the stomach( gastrin, secretin), the pancreas, have hormonal activity. In the oral cavity there are endings of nerve fibers, which convey to the center information about the quantity and quality of food that has arrived.

Therefore, on the back signals, the stomach and intestines are prepared in advance. For example, "an order is formed" for the amount of bile and pancreatic juice needed for digestion in the duodenum. The contractile function that pushes the food lump to the next level is regulated by innervation, wandering and sympathetic nerves are most often involved. They "take care" of the sufficient strength of the wave of peristalsis, alternating or simultaneous contraction of the longitudinal and circular muscles.

An important role belongs to the proper functioning of sphincters. These are muscular pulpit located on the border of the esophagus and stomach, stomach and duodenum. Inside the duodenum, the role of the perforator is performed by the sphincter of Oddi. He lets in the small intestine pancreatic juice and bile from the supply ducts. When going into the blind intestine, the folding of the mucosa plays the role of the valve.

It only works if the gut is located at a certain angle to the end portion of the small intestine. Powerful sphincters of the sigmoid colon allow you to accumulate fecal masses, remove them to the rectal ampoule for the act of defecation. Functional are the diseases that arose due to the discrepancy between the signal information and orders from the brain centers.

Due to impaired contractile activity, stagnation occurs in the stomach, esophagus, intestine. Or, on the contrary, excessive reductions remove undigested residues, do not allow to absorb useful substances and vitamins. Such disorders are called dyskinesias. Failure of compression and relaxation of sphincters causes spasmodic contractions of muscles, expansion of the overlying part of the gastrointestinal tract, insufficient production of enzymes, stagnation with the risk of infection.

Diagnostics is performed by the gastroenterologist

. Most often, functional diseases occur under the influence of stressful situations, hard work, alternation of hungry gaps and overload of digestion, alcohol intake, and narcotic substances. If you do not take action at this stage, pathology becomes organic, accompanied by anatomical changes in the structure of organs, and at the cellular level - by gross deviations in composition and structure. Example, metaplasia of the epithelium - transformation of the stomach cells into intestinal cells with gastritis.

How does the anatomy of the human gastrointestinal tract change in diseases?

Anatomical abnormalities can be identified in vivo with the help of modern diagnostic methods. The use of X-ray studies, ultrasound and endoscopic techniques made it possible to determine not only the type of changes, but also the stage of the process, the degree of damage.

X-ray diagnostics is based on the laws and norms of roentgenotomy. To determine the position, the boundaries of the digestive system, the radiologist can by comparison with the bone skeleton of a person, large muscles. This part of the body is always well contrasted on the screen. Therefore, the localization is considered in relation to the vertebrae, diaphragm, and ribs.

For example, for the stomach, the normal projection of the upper point to the left of the vertebrae is 0.5-2.5 cm below the dome of the diaphragm, the pyloric section is in the zone of the first-second lumbar vertebra, and here the transition to the duodenum is located. At children he lies above. In the esophagus there are 9 segments. The most illustrative picture is when contrasting with a barium solution.

It allows you to judge:

• about the lumen of the internal cavity( changes are detected with tumors, diverticula);
• bias relative to normal localization( gastroptosis, diaphragmatic hernia, compression of the tumor-like formation of neighboring organs);
• violation of the direction and number of folds( smoothing is likely for atrophic gastritis);
• change contours( a symptom of a "niche" in peptic ulcer disease).

X-ray sign of filling defect is typical for tumor, stomach polyp

In X-ray diagnostics, pictures are taken at different angles, the patient is examined in a vertical, horizontal, knee-elbow position. Air in the intestine interferes with the procedure, so a person needs to be prepared in advance( diet, cleansing enemas).To contrast the intestine, irrigoscopy is used - filling with barium through an enema followed by a series of shots.

ultrasound is a technique based on the property of reflecting a sound wave from different tissues. Since the stomach and intestines are hollow organs, the diagnosis is not applied. Various endoscopic techniques( fibrogastroscopy, esophagogastroduodenoscopy, colonoscopy) allow you to visually inspect suspicious areas of the gastrointestinal tract. The most modern apparatus displays a picture on the monitor and makes it possible to record the procedure, take pictures.

The method is indispensable in identifying early stages of cancer, determining the form of inflammation, and finding the source of bleeding. In recent years, the improvement has allowed using some endoscopy to perform some surgical operations, to take biomaterial for histological examination.

Anatomy of the gastrointestinal tract includes mandatory sections for blood supply and innervation. Surgeons need to know how to pass the most important vessels and nerves in order to develop the correct surgical technique and to prevent complications during the operation. The work of the stomach and intestines is provided by glandular organs( liver, pancreas), gall bladder. Together they form an integral system of digestion.