The body is very complex and at the same time surprisingly harmonious. Among the systems that ensure its vital functions, there is one that processes substances that enter the body through food, extracts the most useful of them and disposes of waste products, all of which practically without the conscious participation of the person himself. The large intestine, the structure and functions of which will be examined in more detail, is part of this mechanism. What do we know about him?
Gastrointestinal tract
Any organism needs energy to maintain its vital functions. It can be obtained in many ways. For example, in humans, like in many other animals, the gastrointestinal tract and the digestive system as a whole exist for this purpose.
This part of the body is quite complicated 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 oral cavity, because it is here that food initially enters. First, it is carefully crushed and mixed with saliva, with the help of which the primary cleavage immediately begins, and then it enters the stomach. Here, with the help of various substances, further processing of the incoming and absorption of carbohydrates, part of water, ethanol and some salts takes place.
The next step is the small intestine. This is where the main digestion of food occurs, 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 microgrowths - villi, which significantly increases the absorption area. Also, this department is an important part of the hormonal system, since there is a 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 the rest of the digestive system. And, of course, they are also very important.
Characteristics of the colon
This section of the digestive tract got its name due to the fact that its internal lumen is larger than that of the previous part. It is curious that this is noticeable only at the autopsy of the dead body, while in a living one, the diameter of the large intestine and small intestine are almost the same or differ very slightly. However, this gastrointestinal tract has a wider layer of muscle fibers and connective tissue. But still, the terms “small” and “large intestine” are absent in 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 muscle tissue, there are also submucous membranes and the mucous membrane, which is lined with an organ cavity from the inside. There are no villi in it, but there are a large number of crypts - epithelial depressions that contribute to better reabsorption.
Blood circulation of the colon is provided by the lower and upper mesenteric artery. 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 in general was described a little earlier, begins after the bauginium flap, which separates the ileum and the cecum. This structure does not allow the reverse movement of the chyme - a slurry obtained as a result of digestion of food.
Then the intestine passes up and to the left, encircling the previous section of the gastrointestinal tract, and then again goes down, ending with the anus. Through it, the feces are evacuated, that is, the body gets rid of unnecessary residues. However, sometimes the rectum is isolated separately from the colon. In this case, the last section becomes the part called sigmoid.
Functions
The large intestine does not belong to physiologically active organs. Usually, the main purpose of this body is the formation of feces and the disposal of the body. In fact, the functions of this body are wider.
Firstly, it is here that the extraction of useful substances from food ends. Everything that was impossible to digest earlier is processed. For example, only at this point can fiber be removed. Also, the remnants of water and salts are almost completely drained from the chyme.
Secondly, the human colon is an important part of the immune system. Colonies of bacteria of various types are located here, mostly anaerobic. Some of them help digestion, others prevent the spread of pathogenic microbes, while others produce enzymes that promote the proper functioning of the body, as well as vitamins K, E, B 6 and B 12 , which are necessary for 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 cope with single cancer cells, completely destroying them.
Thirdly, it is the structure of the large intestine, in particular its muscle layer, that ensures the constant movement of digested food. Moreover, a person cannot even control this. 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 cope with almost everything that a person eats as food, you should not thoughtlessly throw anything into yourself. It’s easy to disrupt the intestines, but you can’t notice this right away. And when the symptoms of its malfunction appear, it can be very difficult to restore balance, so it is better to adhere to a healthy diet with enough fiber, which perfectly stimulates the digestive tract.
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 rather complicated despite the fact that there are practically no differences in functions.
So, the appendix adjoins the cecum. The colonic is divided into ascending, transverse and descending, as well as sigmoid sections. Finally, even in a straight line, separation into an ampoule and anus with anus is observed. And each part has its own characteristics. Therefore, it is worth talking about the departments of the large intestine in more detail. All of them are interesting in their own way.
Cecum
This department is located in the right iliac fossa and has the appearance of an almost round sac measuring approximately 6 x 7-7.5 centimeters. It is here that the small and large intestines border. They are separated only by a small valve.
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 superior mesenteric artery approaches the intestine as closely as possible. Divided into a large number of branches, she is responsible for the blood supply to most of it.
Appendix
From the cavity of the cecum through the narrow passage you can get into its appendage, an important, although not a full-fledged department. We are talking about the appendix, or vermiform appendix. For a long time, it was believed that this was only a vestige, since humans are one of the few mammals, along with rabbits and monkeys, who have this part. Experiments were conducted in which the children underwent appendectomy, that is, this appendage was removed at an early age. As a result, many of them had serious immunity problems.
Today it is believed that the appendix is ​​a kind of farm for the beneficial bacteria that inhabit the intestines. Due to its special structure, food masses practically do not fall here. In addition, it is extremely difficult for people with a remote appendix to restore the microflora and establish intestinal function, for example, after taking antibiotics. Nevertheless, it still remains a rudiment, since before taking its present form, it was a full-fledged part of the digestive tract and took part in digestion.
Unfortunately, operations to get rid of this process are made quite often. Appendicitis firmly ranks first among acute surgical operations. Over the year, 4-5 cases of the disease per 1000 people are recorded. 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 a factor such as old age.
Colonic
Immediately after the cecum is 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 subdivision is the transverse colon. As its name implies, it passes from right to left through the peritoneum. It also ends with a bend 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 ileal fossa. She got her name for the S-shaped.
Like other parts of the large intestine, this part is mainly responsible for the absorption of water and electrolytes and the formation of harder contents from the chyme. After the formation of a mass colored in dark color by the enzymes of the gallbladder and consisting of substances unnecessary to the body, exfoliated epithelium, etc., it proceeds 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 pelvic cavity and ends with the anus. It is curious that defecation is a complex physiological process controlled by the cerebral cortex, while in young children it is purely reflex in nature.
Normally, feces make up about a third of everything that was eaten. The frequency and quantity may vary depending on the characteristics of the diet and lifestyle. However, usually the rectum is emptied 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, it is only a matter of increasing 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 a doctor, especially if problems appear often enough.
An important role in the diagnosis is the collection of anamnesis. The doctor may ask about the localization and characteristics of pain, the frequency and nature of the stool in recent years, the 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 establish the foci of pain in the first place.
A study of the stool of the patient is also often used. Analysis for chemical, macro- and microscopic, as well as bacterial composition can give an understanding of many processes in the large intestine. For example, problems with microflora are diagnosed this way.
To evaluate the absorption function, X-ray studies using contrast agents can be used.
Finally, colonoscopy is also used if it is necessary to get a complete picture of what is happening in the intestine. In this study, a probe with a camera and a lamp at the end is inserted inside. With its help, the doctor displays on the monitor an image showing the intestinal cavity from the inside, and can find, for example, neoplasms. With this method, you can examine all parts of the colon.
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 errors in nutrition. In this form, intolerance to lactose, gluten and some other substances may occur. Dysbacteriosis can also bother stool disorders or persistent exacerbations of allergies. In this case, you can not self-medicate and take advertised drugs without consulting a doctor, especially if intestinal disorders occur on an ongoing basis. This can only make matters worse.
Inflammation in any part of the intestine can be quite dangerous. If it is not treated, then the mucous membrane is 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 hemorrhoidal nodes, but both of them require medical attention. Fortunately, almost always the formations are located in the last section, which greatly facilitates access and diagnosis. And, as doctors are inclined to believe, diseases of the intestines, like the entire digestive tract, are almost always the result of malnutrition and lifestyle. Fortunately, modern medicine can, if not completely cure a person, then ease his condition as much as possible and maintain the quality of life with minimal intervention.
Be healthy!