The body is very complex and at the same time surprisingly harmonious. Among the systems that ensure its vital activity, there is one that processes the substances ingested with food, extracts the most useful of them and gets rid of waste, and all this with little or no conscious participation of the person himself. The large intestine, the structure and functions of which will be discussed in more detail, is part of this mechanism. What do we know about him?
human gastrointestinal tract
Every organism needs energy to maintain its vital functions. It can be obtained in various ways. For example, in humans, as in many other animals, there is a gastrointestinal tract and a digestive system in general for this purpose.
This part of the body is quite complex and is responsible for the complete processing of all incoming substances, the maximum extraction of useful and disposal of residues. It all starts in the mouth, because it is here that food initially enters. First, it is carefully crushed and mixed with saliva, with the help of which the primary splitting immediately begins, and then enters the stomach. Here usingvarious substances, further processing of the incoming and absorption of carbohydrates, part of the water, ethanol and some s alts occurs.
The next step is the small intestine. This is where the main digestion of food takes place, the breakdown of carbohydrates, proteins and fats into simpler components and their absorption for transportation and delivery to cells. This is possible due to the special structure of the mucous membrane of this organ. The fact is that the inner surface of the intestine is covered with microoutgrowths - villi, which significantly increases the absorption area. Also, this section is an important part of the hormonal system, since here is the synthesis of some peptide hormones that regulate the activity of the entire gastrointestinal tract and immune processes.
And finally, the last stage of the gastrointestinal tract is the large intestine. The structure and functions of this organ should be considered separately and in more detail, because they are no less interesting than those of other parts of the digestive system. And, of course, they are also very important.
Characteristics of the large intestine
This section of the digestive tract got its name due to the fact that its inner lumen is larger than that of the previous part. It is curious that this is noticeable only when a dead body is opened, while in a living one the diameters of the large intestine and small intestine are almost the same or differ only slightly. However, this section of the gastrointestinal tract has a wider layer of muscle fibers and connective tissue. But still, the terms "small" and "large intestine"missing from the anatomical nomenclature and are considered incorrect.
The length of this organ is usually from 1 to 1.6 meters, the average diameter is about 6.5 centimeters, the exact numbers depend on the specific part. Well, if we talk about the structure of the large intestine, then its walls consist of serous and muscular tissue, there is also a submucosa and the mucous membrane itself, which is lined from the inside of the organ cavity. There are no villi in it, but there are a large number of crypts - epithelial depressions that contribute to better reabsorption.
The blood circulation of the large intestine is provided by the inferior and superior mesenteric arteries. The fibers of the vagus and spinal nerves are responsible for innervation. The outflow of blood is provided by the mesenteric veins.
Location
The large intestine, the anatomy of which was described in general terms a little earlier, begins after the Bauhinian valve, which separates the ileum and the caecum. This structure does not allow the reverse movement of chyme - the slurry obtained as a result of the digestion of food.
Further, the intestine goes up and to the left, encircling the previous section of the gastrointestinal tract, and then goes down again, ending with the anus. Through it, feces are evacuated, that is, the body gets rid of unnecessary residues. However, sometimes the rectum is separated from the large intestine. In this case, its last section becomes the part called the sigmoid.
Functions
The large intestine is not physiologically activeauthorities. Usually, the main purpose of this organ is the formation of feces and getting rid of them by the body. In fact, the functions of this body are wider.
Firstly, this is where the extraction of useful substances from food is completed. Everything useful that was impossible to digest before is processed. For example, only at this stage can fiber be extracted. Also, the remains of water and s alts are almost completely sucked out of the chyme.
Secondly, the human large intestine is an important part of the immune system. There are colonies of bacteria of various types, mostly anaerobic. Some of them help digestion, others prevent the spread of pathogenic microbes, others produce enzymes that contribute to the proper functioning of the body, as well as vitamins K, E, B6 and B12needed by the whole body. In a word, the microflora of the large intestine is an important part of the protective barrier of the human body. And it is so powerful that it can even deal with single cancer cells, completely destroying them.
Thirdly, it is the structure of the large intestine, in particular its muscular layer, that ensures the constant movement of digested food. At the same time, a person cannot even control it. The rate of peristalsis is usually constant and increases after a new portion of food enters the stomach. Thus, the muscles of the colon are responsible for maintaining a more or less constant speed of the food "conveyor".
Despite the fact that the gastrointestinal tract can copewith almost everything that a person uses as food, you should not thoughtlessly throw anything into yourself. It is not difficult to disrupt the work of the intestine, but it may not be noticed immediately. And when the symptoms of a malfunction appear, it can be very difficult to restore balance, so it is better to eat a he althy diet with enough fiber, which is great for stimulating the digestive tract.
Departments of the large intestine: an overview
Traditionally, there are 3 main parts: the cecum, colon and rectum. Each of them also has its own subdivisions, which makes the structure of the organ quite complex, while there are practically no differences in function.
So, the appendix adjoins the caecum. The colon is divided into ascending, transverse and descending, as well as sigmoid sections. Finally, even in the straight line, there is a division into the ampulla and the anal canal with the anus. And each part has its own characteristics. Therefore, it is worth talking about the sections of the large intestine in more detail. All of them are interesting in their own way.
Cecum
This section is located in the right iliac fossa and looks like an almost round bag measuring approximately 6 x 7-7.5 centimeters. This is where the small and large intestines border. Only a small valve separates them.
The main function that this part of the large intestine performs is the absorption of water from the incoming food mass. In general, the structure of this department does not differ from the rest. By the way, it is here that the uppermesenteric artery. Dividing into a large number of branches, it is responsible for the blood supply to most of it.
Appendix
From the cavity of the caecum through a narrow passage you can get into its appendage, an important, though not a full-fledged department. We are talking about the appendix, or appendix. For a long time it was believed that this is only a rudiment, since man is one of the few mammals, along with rabbits and monkeys, who have this part. Experiments were conducted during which children underwent an appendectomy, that is, this appendage was removed, at an early age. As a result, many of them had serious immune problems.
Today it is believed that the appendix is a kind of farm for beneficial bacteria that inhabit the intestines. Due to its special structure, food masses practically do not get here. In addition, it can be extremely difficult for people with a remote appendix to restore the microflora and improve bowel function, for example, after taking antibiotics. However, it still remains a rudiment, because before taking on its current form, it was a full part of the digestive tract and took part in digestion.
Unfortunately, operations to get rid of this process are performed quite often. Appendicitis firmly occupies the first place among acute surgical operations. During the year, 4-5 cases of the disease are recorded per 1000 people. With early access to medical care, the prognosis is favorable. The risk of death is extremely small, but increases when it comes to perforation, as well as in the presence of such a factor asold age.
Colon
Immediately after the caecum comes the next section, which is conditionally divided into 4 parts. The first of them - ascending - goes up the right side to the liver and ends in a smooth bend. The next subsection is the transverse colon. As its name implies, it passes from right to left through the peritoneum. It also ends with a curve, turning into a descending part, going from top to bottom along the left side. The sigmoid colon (the last part of this section) is located in the left iliac fossa. She got her name for the S-shape.
Like other parts of the large intestine, this part is mainly responsible for the absorption of water and electrolytes and the formation of more solid contents from chyme. After the formation of a mass, stained dark by gallbladder enzymes and consisting of substances unnecessary for the body, exfoliated epithelium, etc., it goes further.
Straight
This is the last part of the intestine, the main task of which is to accumulate solid masses and remove them from the body. It is completely located in the cavity of the small pelvis and ends with the anus. It is curious that defecation is a complex physiological process controlled by the cerebral cortex, while in children at an early age it is purely reflex in nature.
Normal stool is about a third of what was eaten. The frequency and amount may vary depending on the characteristics of the diet and lifestyle. Howeverusually emptying the rectum occurs every day, and at the same time a person gets rid of waste weighing from 200 to 500 grams.
Research methods
One of the most common complaints at any age is abdominal pain. Quite often, the matter is only an increase in pressure inside the intestines, for example, due to the accumulation of gases or simply spasms. Nevertheless, this body requires careful attention to itself, and therefore, if you suspect that it is not working properly, you should contact the doctors, especially if problems appear quite often.
Anamnesis plays an important role in making a diagnosis. The doctor may ask about the localization and characteristics of pain, the frequency and nature of the stool in recent years, diet.
The second method of research is palpation. The doctor probes the organs through the anterior abdominal wall, fixing the patient's complaints, paying attention to muscle tension, etc. This helps to first of all identify foci of pain.
Also often used is the study of the patient's stool. An analysis of the chemical, macro- and microscopic, as well as bacterial composition can give an understanding of many processes occurring in the large intestine. For example, this is how microflora problems are diagnosed.
X-ray studies using contrast agents can be used to assess suction function.
Finally, a colonoscopy is also used if it is necessary to get a complete picture of what is happening in the intestines. In this studya probe with a camera and a lamp at the end is inserted inside. With its help, the doctor displays an image on the monitor showing the intestinal cavity from the inside, and can find, for example, neoplasms. This method can be used to examine all parts of the large intestine.
Diseases
In the vast majority of cases of bowel problems, we are talking about disorders of the stool. Diarrhea, constipation, flatulence - most often the cause of these unpleasant phenomena are dietary errors. In this form, intolerance to lactose, gluten and some other substances can occur. Dysbacteriosis can also disturb stool disorders or constant exacerbations of allergies. At the same time, one should not self-medicate and take advertised drugs without consulting a doctor, especially if intestinal disorders occur on an ongoing basis. This can only exacerbate the problems.
Inflammation in any part of the intestine can be quite dangerous. If it is not treated, then the mucous membrane becomes covered with ulcers, and then the processes of decay begin. Even more dangerous is the appearance of formations in the intestinal lumen. It can be malignant tumors or hemorrhoids, but both require medical attention. Fortunately, almost always formations are located in the last section, which greatly facilitates access and diagnosis. And, as doctors tend to believe, almost always diseases of the intestines, like the entire gastrointestinal tract, are the result of malnutrition and lifestyle. Fortunately, modern medicine is capable of, if not completely curing a person, thenalleviate his condition as much as possible and maintain the quality of life with minimal intervention.
Be he althy!
