The intestines are the most important part of the digestive system. It is located in the abdominal cavity. Various processes related to food digestion and absorption occur in it. nutrients. This structure begins with the duodenum and ends with the anus.

The mucous membrane of the intestinal tract produces a number of biologically active substances that are simply necessary for the physiological breakdown of products. Knowledge of the location and structure of this the most important body, as well as an understanding of how it works, helps to navigate when providing first aid.

Intestinal anatomy

How many meters is the intestine of an adult? The organ is structurally divided into two main parts - the small and large intestine. The length of the first section can reach four meters. The small intestine is shorter in women than in men. It consists of three main departments:

• duodenum;
• skinny;
• iliac.

This department is responsible for digesting food. It has a small diameter and thin walls. Moreover, this structure covers almost the entire lower space of the abdominal cavity and even partially the pelvis. The thin section is also responsible for moving feces further along the intestinal tract, hormonal secretion and strengthening the immune system. The overall work of the enzymes of the small intestine, gall bladder and pancreas ensures the breakdown of the food bolus into monocomponents.

Attention! The average length of the human intestine is four meters. The thin section is longer than the thick section.

The thick section can reach one and a half meters. Anatomically it consists of the following parts:

• blind;
• ascending;
• descending;
• transverse;
• straight;
• sigmoid.

After death, the length of the human intestine can reach eight meters. This is due to muscle relaxation. There are no villi on the mucous membrane of the large intestine. There is no active absorption of nutrients here.

This section of the intestine is necessary for the proper formation of feces. Here the absorption of water and the formation of feces from chyme occurs. Along the intestinal wall there is an accumulation of lymphoid tissue. She takes an active part in the processes of the immune system.

The photo shows the structural features of the gastrointestinal tract

Departments

Let's talk about the two main sections of the intestinal tract: the small and large intestine.

Thin

The small intestine is a multifunctional organ, the activity of which determines the coordinated functioning of the entire digestive system. It performs a secretory function, that is, it secretes juice necessary for the breakdown of food. Digestive secretions include mucus, which prevents the intestines from self-digesting.

In addition, the organ performs an absorptive function. Nutrient compounds are absorbed through the mucous membrane. The structure of the mucous layer of the intestinal wall ensures the absorption of exclusively beneficial elements. Endocrine function is ensured by the ability of cells to secrete peptide hormones. They affect the functioning of not only the intestinal tract, but also the entire body.

The muscle structures of the organ are responsible for motor function. The contraction of these muscles ensures digestion, separation of the food bolus and its further pushing. Diseases of the small intestine can have an inflammatory, functional or tumor nature. Some pathologies are congenital, while others are acquired.

Thick

The thick section has larger dimensions and a wider diameter. Three muscle bands are responsible for peristalsis and the movement of feces. Muscle structures are unevenly distributed. Upon examination, it looks like a cluster of bulges and constrictions.

Attention! Most of the beneficial bacteria live in the large intestine.

The main function of this department is the formation of feces. After entering the thick sections, chyme loses liquid, so its structure changes, it becomes denser and takes on the appearance of feces. A common disease of the large intestine is ulcerative colitis. Chronic inflammation of the mucous membrane causes destructive changes and the formation of ulcers.

The reasons are still not fully understood, but scientists note a connection between UC and genetic factors. The influence of smoking and oral contraceptives on the development of chronic intestinal inflammation was also recorded. Patients develop diarrhea with the release of scarlet blood. There is pain in the abdominal area.

Another common pathology is Crohn's disease, which causes granulomatous inflammation. The disease can affect any part of the gastrointestinal tract and causes intestinal upset. The number of bowel movements per day can reach up to twenty times a day.

According to statistics, in developed countries, older people are at risk of developing diverticulosis. The pathology is characterized by the appearance of protrusions on the intestinal wall. The main role in the formation of the disease is played by poor nutrition, in particular, an addiction to flour and meat dishes, along with a lack of plant foods.

The intestinal tract consists of two main sections: the small intestine and the large intestine.

Physiology

Digestion of food begins in the mouth. Chewing thoroughly helps make this process easier. Next, the food bolus enters the esophagus, stomach and duodenum. In the initial part of the organ, food combines with bile secretions and pancreatic enzymes. Under the influence of these excreta, the food bolus is broken down.

The muscle layer ensures uniform distribution of nutrients along the inner wall. In addition to digestive function, the human intestine is responsible for endocrine and immune processes. Special microflora improves digestion processes and is responsible for the secretion of vitamins.

The intestines are responsible for the flow of hydrochloric acid into the stomach, due to which the primary processing of food occurs. Next, the eaten foods are broken down into individual components. From these the body takes for itself essential microelements and water. Then the formation of feces and their further evacuation occurs.

Important! The structure of the human intestine begins with the pylorus of the stomach and ends with the anus.

The job of the intestines is to absorb nutrients from food digested by the stomach. All these processes are supported by bacteria that form microflora. In addition, the intestine is an organ of the immune system. It serves as a barrier to pathogens trying to attack the human body.

Microflora

The intestinal tract is inhabited by the following bacteria:

• lactobacilli;
• bifidobacteria;
• bacteroides;
• enterococci;
• coli;
• Proteus;
• staphylococci;
• fungi.

The first three names refer to the main group of microorganisms present in the intestines. In addition to beneficial bacteria, the microflora also consists of opportunistic microorganisms. Under the condition of strong immunity, these bacteria do not cause any disturbances in the body, but when the immune forces are weakened, these same microorganisms get out of control, begin to actively multiply and can cause serious abnormalities in the body.

Interesting! The human intestine is inhabited by microorganisms that are seventy times more numerous than the number of inhabitants of the globe.

Bacteria present in the intestines are divided into two main groups: anaerobes (do not require oxygen) and aerobes (live on oxygen). The overwhelming number of microorganisms in the intestinal tract are anaerobes: lactobacilli, bifidobacteria, bacteroides. And, for example, E. coli and enterococci are aerobes.

Violations

Bad job the digestive organ can be associated with several factors at once. The more factors that affect the intestines at the same time, the more severe the pathology and the more difficult it is to treat. The following reasons play a role in the development of intestinal tract diseases:

• genetic predisposition;
• weakened immunity;
• poor nutrition;
• bad habits;
• passive lifestyle;
• some medicines;
• intestinal infections.

The following symptoms unite intestinal diseases:

• Abdominal pain. The pain syndrome can be intense aching or even sharp paroxysmal. In some cases, it appears in episodes or is associated with food intake. In some diseases, patients can name a clear localization of pain, while in other disorders, the pain outbreak is diffuse. For example, when the small intestine is damaged, discomfort occurs in the umbilical region. Diffuse pain is more characteristic of intestinal bloating due to stretching of the walls by gases.
• Flatulence. This symptom occurs due to excess accumulation of gases. The cause of this condition may be fermentation processes, intestinal atony or decreased motor function.
• Decreased appetite. In fact, patients develop a fear of eating. This is explained by the fact that after a meal the intestines begin to actively contract and secrete digestive juices, which provokes painful attacks.
• Constipation or diarrhea.

Intestinal diseases usually develop against a background of weakened immunity

Heart attack

A heart attack is the death of the intestinal wall. Impaired blood flow can occur due to blockage or spasm. The insidiousness of this pathology lies in the difficulty of diagnosis. Without an angiographic study, it is almost impossible to make a diagnosis.

The pathology manifests itself in the form of sudden cramping pain in the abdomen, nausea, vomiting, and diarrhea. Given the fact that most often the disease is detected in late stages, treatment is mainly surgical. Conservative therapy It is advisable to use before the development of signs of peritonitis.

Dyskinesia

The pathology is based on deterioration of intestinal tone and motility. Organic damage are not detected during examination, but functional activity is significantly reduced. Dyskinesia causes indigestion. Pathology often develops against the background of neurological disorders. This is why dyskinesia is most often diagnosed in women.

Dyskinesia is divided into hypertonic and hypotonic types. In the first case, persistent spastic contractions of the intestine are observed. They may cause chronic constipation and painful colic. The pathology causes acute cramping pain lower abdomen and iliac regions.

The painful outbreak subsides for some time after defecation, and after eating it returns again. Chronic intoxication the body leads to mental and physical decline in performance. At hypertensive dyskinesia There may be no bowel movements for several days, and then a large amount of feces is passed.

With hypotension, on the contrary, peristalsis is weakened. Patients are bothered by dull painful cramps in the abdomen, a feeling of fullness, and bloating. Feces pass with great difficulty and in small quantities. This causes poisoning of the body.

Endometriosis

Benign neoplasm occurs due to the entry of endometrial cells of the uterus into other organs. Play a major role in the formation of the disease hormonal changes, hereditary predisposition, weakened immunity. When the external intestinal muscles are affected, nausea and abdominal pain occur during menstruation. If the sigmoid colon is involved in the process, the pain attack is localized in the left lower abdomen.

The following symptoms are typical for endometriosis:

• pain in the depths of the pelvis and anal passage during critical days;
• constipation or diarrhea;
• painful bowel movements;
• the appearance of blood and mucus in the stool;
• increased bowel movements during menstruation.

In women, intestinal endometriosis can cause pain during intercourse, as well as prolonged and heavy menstruation. Drug treatment is aimed at normalizing hormonal levels, since intestinal endometriosis is only a secondary process.

Normalization of work

It is not customary to talk about intestinal problems out loud. Many are even embarrassed to ask a doctor about how to improve the functional activity of the intestines. In this subtitle we will talk about effective tips that will help restore the functioning of the intestinal tract and get rid of unpleasant symptoms.

The main role in improving the functioning of the gastrointestinal tract is, of course, nutrition. Not only the diet is important, but also the diet. Get rid of the habit of eating on the go or in a hurry. Try to eat slowly, chewing each bite thoroughly. The food should be swallowed in the form of a liquid paste.

Important! Experts advise not to talk while eating. Otherwise, air may get in with the food, which will cause bloating.

Replace tea and coffee with plain water. Our favorite drinks slow down the functioning of the intestines, but water, on the contrary, normalizes it. Give up the habit of eating in front of the TV screen. So, you can eat more and swallow unchewed pieces of food. Try to eat more fiber. It is present in vegetables and fruits.

You can also buy fiber at the pharmacy in powder form. Set a goal to drink a glass of natural water on an empty stomach after waking up. This will help launch the gastrointestinal tract. If possible, eat your meals at the same time every day. Try not to overeat, especially in the evening hours.

Do not drink water with food, keep at least a half-hour interval

Don't forget about exercise. Moderate physical activity improves intestinal motility. Sport helps us develop resistance to stress, but emotional shocks can also cause disturbances in the gastrointestinal tract. Remember to set aside time for sleep and relaxation.

Medications will help normalize bowel function. Let's consider the rating of the most effective means that normalize motor skills:

• Lactulose. Has a mild laxative effect. The drug is even prescribed for the treatment of children and pregnant women. Lactulose normalizes microflora and motility, but does not have a quick effect;
• Mucofalk. This is a herbal medicine that contains plantain seeds. Also approved for use during pregnancy;
• Itopride. This is a new generation prokinetic agent. Has a dual mechanism of action. It is recommended to use it already in the initial stages of illness;
• Prucaloprid. An enterokinetic agent is used in the treatment of chronic constipation. The drug stimulates intestinal motility. Prucalopride is prescribed during pregnancy and lactation.

To summarize, it can be noted that the intestines play a vital role in the functioning of our body. It consists of two main sections - small intestine and large intestine. The intestinal tract begins with the gastric sphincter and ends with the anus.

Malfunctions in the functioning of this structure affect the functioning of the entire organism as a whole. A healthy lifestyle, including a moderate diet physical exercise, stress resistance, will help prevent intestinal dysfunction.

90% of people are susceptible to gastrointestinal diseases based in the large intestine. The intestine is divided into two areas: thin and thick. The large intestine is the lower section of the gastrointestinal tract. The length is two meters. Its wall is covered with a serous membrane.

Structure of the digestive organ:

A common disease that subsequently causes abdominal pain that radiates to the leg is appendicitis. In this case, the intestine on the right hurts.

Different parts of the intestine perform their assigned functions. In order for the intestines and digestive system to work efficiently, it is necessary that the remaining parts work smoothly.

Performs a number of important functions in the human body:

• Digestive. Final treatment of final products with molecules that accelerate chemical reactions, as well as the release of residual nutrients from it.
• Suction. Nutrients are absorbed.
• Muscular. Promotes the movement of colon contents. Responsible for removing harmful substances from the body.

The health of the body directly depends on the proper functioning of the large intestine. Most people develop slagging. It doesn't always depend on a person's constitution. Cleansing is considered the most important among other cleanses of the body.

Colon diseases

Typically, with pathology, pain is localized on the side of the abdomen. A lot of complaints from patients are about pain in the intestine on the left, this is due to infectious inflammation, which intensify with movement.

Ulcerative colitis

Pathological disease. With this disease, the mucous membrane of the colon suffers. A sign of the disease is a long course with worsening symptoms. Painful symptoms are localized at the bottom left.

The etiology of the disease is still unknown. Suggestions have been made about the involvement of hereditary pathology of the immune system. Patient complaints of weakness, weight loss, and general malaise are typical. Disease management continues for a long time. It is recommended to eliminate dairy products due to increased sensitivity to milk proteins.

Proctitis

Inflammatory process due to constipation, injury, infection. Cancer often progresses in the rectal area and benign formations tissues above the mucous membrane. The anus is prone to pain that increases when walking.

Causes of proctitis:

• Nonspecific ulcerative colitis.
• Diseases that are not pathological in nature.
• Infectious etiology.
• Venereal infectious diseases.
• Frequent use of certain groups medicines.
• Food allergic reactions.
• Various pathologies.

Ischemic colitis

The main symptom is stenosis, which provokes inflammation. At the initial stage of the disease, there is short-term pain in the left side of the abdomen. Subsequently, an ulcer may develop. Mainly progresses in the sigmoid and transverse colon.

Colon tumors

There are two types of tumors: benign and malignant. Most common malignant appearance. Today, colorectal cancer is the most common malignant tumor.

There are extremely few specific indicators by which cancer can be detected at the initial stage. If you have intestinal disorders, it is important to seek help from a doctor in order to identify a tumor in the intestines at an early stage.

Irritated colon

A group of intestinal disorders expressed by pathologies of motor function in the absence of organic changes. Patients begin to experience stomach pain, stool disturbances, and bloating. The nature of the pain is uncertain - sharp, stabbing, cutting.

Treatment depends on the doctor's ability to identify the etiology that is at the root of the disease. Doctors recommend following a loyal diet. At chronic course disease, dysbacteriosis or a disorder of a group of microorganisms found in natural conditions intestines.

Diverticulosis

As a result of the disease, local pouch-like protrusions appear in the intestinal wall. They often form in older people. The reason is an insufficient amount of plant-based food in the diet. In addition to constipation, the formation of diverticula is promoted by:

• Excessive body weight.
• Excessive use of laxatives.
• Increased gas formation.

The main method in treating the disease is to regulate bowel movements.

Dolichosigma

Extended. It can be either congenital or acquired. The course of the disease occurs without obvious symptoms. Usually treatment is conservative and aimed at normalizing stool. Surgical intervention required for resection of the accessory sigmoid loop.

Megacolon

Enlargement of part or all of the colon. The need for surgical intervention depends on the form of the disease. If surgery is required, the enlarged part is removed.

Treatment of diseases

Timely assistance from an experienced expert is considered an important step. Under no circumstances should you engage in treatment on your own; this is harmful to your health. Only a doctor has the right to prescribe a working treatment regimen. There are known ways to combat the disease.

Drug treatment

Depends on the type of disease. The pathological process is caused by a number of factors:

• Infection.
• Poisoning.
• Poor nutrition.
• Dysbacteriosis.

Therefore, the method of therapy is prescribed after establishing the etiology of the disease and the dominant symptoms. When treating inflammation, drugs are prescribed that normalize the composition of the microflora. Surgery is required when diagnosing autoimmune inflammation.

Traditional methods of treatment

Traditional methods of treatment give favorable results. For several types of colon diseases, original methods are allowed. The method is selected according to the type of disease. In folk medicine there is an abundance of homeopathic treatment methods based on the natural qualities of medicines. Use along with medications shows the best results.

Diet

Drug treatment should be accompanied by diet. The food is prepared from organic products. Steaming is recommended. Unhealthy fried and smoked foods should be completely excluded from the diet. You need to eat often, in small portions.

Surgery

Surgery is indicated only for several types of diseases: the acute form of Crohn's disease, which affects the entire digestive tract, ulcerative colitis, and also when deterioration occurs. The damaged area of ​​the intestine is removed, restoring continuity and patency. I am glad that surgical intervention is required only as a last resort.

Disease Prevention

Prevention includes:

• Maintaining a healthy lifestyle.
• Avoidance of stressful conditions.
• Elimination of constipation.
• Diseases eliminated in time.
• Systematic visits to the doctor for the purpose of preventive examination.
• Sleep for at least 8 hours.
• Regular exercise as much as possible.
• Monitoring the state of intestinal microflora.
• Compliance with hygiene standards.

The pathology of the large intestine affects the patient's condition. The described diseases often exhibit a long-term course and are subject to seasonal deterioration. Required A complex approach to get rid of the disease.

It is necessary to take into account that diseases are easy to prevent in order to avoid worsening the condition in the future. Remember, even with the slightest changes in normal operation: painful sensations, unusual manifestations - a visit to the doctor is equivalent to a mandatory action.

The human body is a reasonable and fairly balanced mechanism.

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Sections of the intestine in order

The structure of the small and large intestines for dummies

I was going to write a review about the new kind surgical operations on the intestines, but I thought that first I should tell you about the structure of this very intestine. When I was in school, I sometimes got confused which intestine goes with which. Therefore, today we are closing this gap. You will even find out which gut was called hungry and why.

There will be a short course in anatomy, get ready. I threw out the unnecessary, here - only the most interesting.

The human intestine consists of two sections - thin and thick. Why was it called that? The diameter of the small intestine at the beginning is 4-6 cm and gradually decreases to 2.5-3 cm. The large intestine has an average diameter of 4-10 cm. Even a poor student can distinguish them by their appearance, but more on that below.

DIVISIONS OF THE INTESTINE (the names are English, although they are similar to Latin) Esophagus - esophagus. Liver - liver.

Small intestine - small intestine.

Colon - colon(part of the large intestine). Rectum - rectum.

When I was preparing this material, I almost got confused: the textbooks give different figures about the length of the small intestine. The answer is simple: in a living person the length of the small intestine is 3.5 - 4 meters, and in a dead person it is about 6-8 m due to the loss of intestinal tone, that is, 2 times more. The length of the large intestine is much smaller - 1.5 - 2 meters.

Small intestine

The small intestine has 3 sections:

1. Duodenum (lat. duodenum, read “duodenum”, emphasis everywhere on the penultimate syllable, unless I have emphasized otherwise): the initial section of the small intestine, has the shape of the letter “C” and a length of 25-30 cm (21 cm in a living person ), goes around the head of the pancreas, the common bile duct and the main pancreatic duct flow into it (sometimes there is an accessory pancreatic duct). The name is given according to the length of this intestine, which ancient anatomists measured on their fingers (they did not use rulers). In ancient times in Rus' the finger was called a finger (“index finger”).
2. jejunum (jejunum - empty, hungry): represents the upper half of the small intestine. Have you ever wondered why the intestine was called “hungry”? It’s just that at autopsy it often turned out to be empty.
3. ileum (ileum, Ileum - from the Greek ileos to twist): is the lower half of the small intestine. There is no clear boundary between the jejunum and ileum, and they themselves are very similar in appearance. Therefore, anatomists agreed that the upper 2/5 of the small intestine is the jejunum, and the lower 3/5 is the ileum. Calculate the length in meters yourself.

DIVISIONS OF THE SMALL INTESTINE in Latin. Duodenum - duodenum. Jejunum - jejunum. Ileum - ileum.

Inflammation of the duodenum is called duodenitis (have you heard the term gastroduodenitis?). In practice, inflammation of the jejunum and ileum is not isolated separately, but is called general term enteritis (inflammation of the small intestine) from the Greek enteron - intestines.

The typical microscopic structure of the intestinal wall is (from inside to outside):

• mucous membrane,
• submucosa,
• muscle layer:
• internal circular (circular),
• external longitudinal (only three ribbons remain in the large intestine, more about them below),
• serous (outer) layer.

LAYERS OF THE INTESTINAL WALL (see the pronunciation of Latin words in parentheses, the rest - in the English-Russian dictionary) Tunics - membranes,

mucosa (mucosis) - mucous membrane,

submucosa (submucosa) - submucosa,muscularis (muscularis) - muscle layer (inner - internal, outer - external), serosa (serosa) - serous membrane (here the peritoneum), mesentery - mesentery.

The mesentery (mesenterium, mesenterium) is a fold of the peritoneum that attaches the intestines to the posterior wall of the abdominal cavity; vessels and nerves pass through it. You can compare the structure of the intestinal wall with the structure of the esophagus wall, which I wrote about earlier in the article about poisoning vinegar essence.

Colon

Let's move on to the large intestine. One of my favorite questions in anatomy is to name external differences large intestine from the small intestine. There are 5 of them, if I haven't forgotten:

1. grayish color,
2. large diameter,
3. the presence of three longitudinal muscle bands (this is what remains of the longitudinal muscle layer of the wall),
4. the presence of swellings (protrusions of the wall) - haustrum,
5. presence of omental processes (fat pads).

FEATURES OF THE LARGE INTESTINE (clockwise from its beginning) Ileum - ileum, Vermiform appendix - vermiform appendix (appendix), Cecum - cecum, Ileocecal valve - ileocecal valve, Superior mesenteric artery - superior mesenteric artery,

Haustrum - haustra,

Right colic flexure - right colic flexure, Transverse mesocolon - mesentery of the transverse colon, Left colic flexure - left colic flexure,

Epiploic appendages - fatty appendages,

Tenia coli - muscle band, Inferior mesenteric artery - inferior mesenteric artery, Sigmoid mesocolon - mesentery of the sigmoid colon, Rectum - rectum,

Anal canal - anal canal.

The large intestine has several sections:

1. cecum (cecum or caecum, tsekum): length 1 - 13 cm; This is the area of ​​the large intestine below the confluence of the ileum, that is, below the ileocecal valve. From the place where the three ribbons converge, a vermiform appendix (appendix) extends, which can be directed not only downwards, but also in any other direction.
2. ascending colon (colon ascendens, colon ascendens)
3. transverse colon (colon transversum, colon transversum)
4. descending colon (colon descendens, colon descent)
5. sigmoid colon (colon sigmoideum, colon sigmoideum): length is very variable, up to 80-90 cm.
6. rectum (rectum, rectum): length 12-15 cm. Diseases of this intestine are dealt with by doctors of a separate specialty - proctologists (from the Greek proktos - anus). I will not describe the structure of the rectum here; this is a complex topic.

DIVISIONS OF THE LARGE INTESTINE (in order) cecum - cecum, ascending colon - ascending colon, transverse colon - transverse colon, descending colon - descending colon, sigmoid colon - sigmoid colon, rectum - rectum.

I explained the structure of the intestines in a simplified form. Students learn in more detail: how they are covered with peritoneum, whether they have a mesentery, how they are supplied with blood, what they border on, etc.

Inflammation of the large intestine is called colitis. Inflammation of the rectum should be called proctitis, but this term is rarely used. More often used is paraproctitis - inflammation of the tissue around the rectum (para - about).

Addition dated February 29, 2008. Inflammation of the cecum is called typhlitis (from the Greek typhlon - cecum). You are unlikely to need the name, but I added it here to make the presentation encyclopedic.

What’s interesting: the small and large intestines differ not only in structure and function. They get sick differently. Diarrhea (diarrhea) with enteritis is very different in appearance from diarrhea with colitis. But more about this some other time. If anyone wants to read it. 🙂

• What types of diarrhea are there?
• Treatment of diarrhea

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The structure and length of the human intestine

The intestine is located in the abdominal cavity and is the longest part of the gastrointestinal tract. It starts immediately from the stomach and ends at the anus. Like the pancreas, it is part of the immune and digestive systems. In this organ, food is absorbed and digested, some hormones are synthesized, immune processes occur, harmful toxins are eliminated and hazardous substances.

Intestinal sizes

The intestine consists of the small and large intestines. They received this name because of the difference in diameter. The diameter of the large intestine is 4-10 centimeters, and the small intestine gradually narrows from 4-6 centimeters to 2.5-3 centimeters.

The large intestine reaches a length of 1.5-2 meters. During life, the length of the human small intestine is approximately four meters; after death, its muscles relax, and it stretches to 7-8 meters. Men have a longer small intestine than women.

At birth, the length of the human intestine is about three meters, it is 6 times greater than the height of a newborn!

Structure of the small intestine

Small intestine starts from the stomach and ends in the large intestine. It is where food is mainly digested. It is covered with peritoneum and has the so-called mesentery, consisting of two sheets of peritoneum, passing from the intestine to the posterior wall of the abdominal cavity.

The mesentery attaches the posterior wall of the abdominal cavity to the intestines. It is permeated with nerves, blood vessels and lymphatic vessels. Thanks to it, the intestine forms loops.

The small intestine bends many times and in turn consists of the duodenum, jejunum and ileum.

The shape of the duodenum resembles the letter “C”. Its length is 21 centimeters, previously measured in fingers. Because of this, it received such a name. The jejunum is often called hungry because it is almost always empty when opened. There is no clear boundary between the ileum and jejunum.

In the place where the small intestine passes into the large intestine, the bauginian valve is located, allowing the contents of the small intestine to move only in one direction - to the large intestine.

Structure of the large intestine

The large intestine is bottom intestines. It is located closer to the side walls of the abdominal cavity and has a bend similar to a rim. Its length is approximately 1.5 meters, its diameter exceeds that of the thin one. It absorbs water and forms feces.

The large intestine consists of:

• cecum - its length is 1-13 centimeters;
• ascending colon;
• transverse colon;
• descending colon;
• sigmoid colon, shaped like the letter S - its length is 80-90 centimeters;
• rectum - 12-15 centimeters long.

A vermiform appendage called the appendix extends from the cecum. Previously, it was considered a vestige. But in Lately found that it delays and destroys pathogenic microflora, and also ensures normal intestinal motility.

The structure of the intestinal wall

The intestinal wall consists of 4 layers:

• mucous membrane;
• submucosa;
• muscle layer;
• outer serous layer.

Villi extend from the mucous membrane of the small intestine, providing an increase in the absorption surface of the intestine. There are no villi in the mucous membrane of the large intestine, but there are crypts and folds.

The muscle layer has 2 layers.

It consists of:

• internal circular or circular layer;
• external longitudinal

Differences between the small and large intestines

The large intestine differs from the small intestine:

• grayish in color (small intestine is pink);
• large diameter;
• thinner wall;
• the presence of 3 longitudinal muscle bands instead of the longitudinal muscle layer of the wall;
• the presence of protrusions of the wall, which are called haustra;
• the presence of omental processes.

Bowel functions

IN small intestine Most of the digestive processes take place. The ducts of the pancreas and liver open here, releasing digestive enzymes. Here, proteins, fats and carbohydrates are residually broken down, and the resulting monosaccharides, amino acids, fatty acids and monoglycerides are absorbed into the blood.

Water is absorbed in the large intestine, and feces are formed from chyme - undigested food mass.

Thanks to various contractions (rhythmic segmentation, pendular, peristaltic and antiperistaltic contractions), the contents of the intestine are mixed, ground and moved.

Also in the intestine, the synthesis of hormones and immunoglobulins occurs, due to which cellular immunity is realized.

Intestinal microflora

The “indigenous inhabitants” of the intestines are lactobacilli, bifidobacteria and E. coli. Sometimes staphylococci penetrate into it. If the human body has a strong immune system, then bacteria do not cause any problems. In addition, they synthesize useful enzymes and vitamins and protect the body from constipation. If the immune system weakens, bacteria can cause dysbiosis or other complications.

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Sections of the large intestine: developmental features and possible diseases

Content:

1. Anatomy
2. In newborns
3. Diseases

Knowledge of the anatomy of the gastrointestinal tract allows us to more accurately establish the localization and nature of the pathological process. The intestines are one of the most important parts of the digestive system. It is divided into several departments that are responsible for various functions and contribute to bolus processing. End part digestive tract- This is the large intestine. The sections of the large intestine have a complex structure, which it is advisable to know in order to be able to adequately describe your complaints and symptoms to the doctor in case of illness.

IMPORTANT! Natural remedy Nutricomplex restores correct exchange substances for 1 month. Read the article> >...

Colon Anatomy

Anatomy

The anatomy of the large intestine is quite complex and unique. Upon visual inspection, the sections of the intestine are very easy to distinguish from each other. The large intestine is larger and has a wider lumen compared to the thin intestine.

There are 3 muscle bands running longitudinally along the colon. They are necessary for performing peristaltic movements and pushing feces. The muscle layer is located unevenly on the intestine, which upon visual inspection resembles a cluster of constrictions and bulges.

Most of the microflora ( good bacteria) lives precisely in the large intestine. The main function of the human large intestine is the formation of feces. Since absorption of nutrients in the colon, as a rule, does not occur, the mucous membrane draws water onto itself. Food digested in the stomach and small intestine is called chyme. Once in the thick sections, chyme begins to actively lose water, its structure changes, it becomes denser and turns into ordinary feces at the exit. Up to 4 liters of chyme pass through the colon per day, and up to 200 g of feces are released.

The length of all sections of the intestine is approximately 11 meters. This indicator may vary depending on the constitution, height and gender of the person. The small intestine consists of the duodenum, jejunum and ileum. In these departments, digestion of the food bolus and absorption of nutrients mainly occur. The total length of the small intestine is about 7-8 meters. The length of the large intestine of an adult will be 3-4 meters.

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Bowel course

The cecum is a kind of appendage that occupies an intermediate position between the small intestine and the transverse intestine. Located in the iliac region on the right. The posterior side touches the iliacus and psoas major muscles. The anterior surface of the intestine is in contact with the anterior abdominal wall. There is no mesentery of its own, but it is completely covered by the peritoneum. on her inner surface 3 muscle bands converge. In this location there is a vermiform appendix, better known as the appendix. Its length is up to 20 cm. The process can be located almost anywhere.

The ascending colon then arises from the cecum. It runs along the right side of the abdomen to the hypochondrium. Having reached the liver, it turns sharply to the left and passes into the transverse colon. It goes in the direction of the splenic angle, where it successfully passes into its descending section. Descending department The colon runs parallel to the ascending colon, but only in the left half of the abdomen. In the left iliac region it passes into the sigmoid colon. The descending colon is covered by peritoneum only on three sides, unlike the sigmoid colon. At the level of the junction of the sacrum with the ilium, the sigmoid colon passes into the rectum, which ends at the anus.

The mucous membrane of the colon does not have villi. With the exception of the semilunar folds, which are arranged in three rows, the surface of the mucosa is smooth. The submucosal layer is well developed, and the muscle wall is represented by longitudinal and circular fibers. Longitudinal are the same 3 ribbons located along the entire colon. The circular layer is developed evenly throughout. TREAT THE CAUSE, NOT THE EFFECT! Nutricomplex, a product made from natural ingredients, restores proper metabolism in 1 month. Read the article>>...

Rectum

Located in the pelvic cavity. It has an upper wide and lower narrow part. The upper section is represented by the rectal ampulla, and the narrow one passes through the perineum and is called the anal canal.

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In newborns

Since at birth the digestive tract has not yet completed its development, in infants the large intestine has a number of characteristic features. Its functions are similar to those in adults, however, upon visual examination one can detect the absence of typical bulges and constrictions. Omental formations begin to appear only by the third year of life, and the total length at birth reaches no more than 65 cm. By the second year, the length should increase by 20 cm. The colon will be fully formed only by the fifth year. Since the sections of the intestine develop unevenly, some sections may not be located where they are in adults. For example, the cecum in infants is located under the liver. As the child grows, the blind angle begins to descend into the right iliac region.

In infancy, the cecum merges so smoothly into the appendix that sometimes it is not possible to distinguish them from each other. The shortest department in at a young age this is the ascending part of the colon, only 2 cm. For some time it maintains this size, but in the second year it begins to actively grow.

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In adults, the sigmoid colon is localized in the pelvis. In children, this area is poorly developed, so the intestine has to move into the abdominal cavity for some time. By the age of 5, when pelvic bones are already reaching required size, the intestine takes its usual place.

The information given in the text is not a guide to action. To obtain more detailed information about your disease, you should consult a specialist.

Diseases

There are a number of pathologies that can affect the function and integrity of the colon. As a rule, the main complaints in such patients are stool disturbances, pain in the left or right iliac region, prolonged constipation or bleeding from the rectum. With diarrheal syndrome, the patient's appearance will be cachectic, emaciated, or even dried out. To clarify the diagnosis and find out the cause of the disease, it is necessary to use all available research methods, including both laboratory tests and instrumental manipulations.

Nonspecific ulcerative colitis

This disease is characterized by chronic inflammation of the intestinal mucosa, leading to destruction and ulceration. The causes of the disease have not yet been established, however, researchers have identified several theories. It was noted that if a patient's immediate family suffers from UC, then there is a high risk of developing this disease. The influence of oral contraceptives and tobacco smoking on the development of chronic intestinal inflammation was also recorded. The course of the disease is characterized by alternating stages of relapses and remissions.

Upon initial admission, patients complain of frequent loose stool with admixtures of scarlet blood. There is pain in the abdominal area, and sometimes there is a false urge to defecate (tenesmus). With prolonged diarrhea, dehydration develops. Treatment is carried out with the help of hormonal drugs (prednisolone, dexamethasone). IN severe cases accompanied by dehydration and blood loss, blood transfusion and rehydration therapy are prescribed. If carcinoma is suspected, the leading treatment tactic is surgery.

Crohn's disease

Ulcerative colitis and Crohn's disease are diseases included in the clinical group of nonspecific inflammatory bowel diseases. Crohn's disease is a pathology in which granulomatous inflammation of the mucous layer of the digestive tract occurs. Unlike ulcerative colitis, it can affect not only the large intestine, but also any other part of the gastrointestinal tract. Clinically, the disease is manifested by constant or nocturnal diarrhea, abdominal pain, exhaustion and night sweats. The number of bowel movements per day can range from 6 to 20 or more times. When examining the stool, impurities of mucus and blood will be found in it. With this pathology, all functions of the large intestine are significantly affected.

Comparison of affected areas between Crohn's disease and ulcerative colitis

Megacolon

A disease caused by hypertrophy of the entire colon or certain sections. The pathology is congenital and is associated with underdevelopment of the innervation apparatus. Clinically manifested by early constipation, pain, flatulence, increased abdominal size, and intoxication. Bowel emptying is carried out only with the help of cleansing enemas. The feces of such patients have an unpleasant putrid smell, contain mucus, blood and particles of undigested food. In addition, megacolon can develop in a person during life as a result of various organic diseases of the large intestine.

Diverticulosis

Pathology of the large intestine, accompanied by the formation of thin-walled pouch-like protrusions from the intestinal wall. Statistically, the highest incidence is observed in developed countries, in older people. Among the leading reasons are the decrease in the share of plant foods in the diet and the predominance of meat and flour dishes. Such a diet leads to constipation, which contributes to the development of changes in the intestinal wall. Clinically, such patients experience pain in the left iliac region of the abdomen, stool disturbances such as alternating constipation and diarrhea, as well as bloating and flatulence.

Diagram of diverticulosis of the sigmoid colon

Dolichosigma

This is a pathological condition caused by abnormal elongation of the sigmoid colon. When examining the intestine, you can notice that only the length of the intestine changes, but the diameter remains normal. Clinically, the disease is manifested by periodic constipation, bloating and abdominal pain. In confirming the diagnosis, irrigography and X-ray contrast examination of the intestine occupy a special position. Physiotherapy, massage, cleansing enemas and laxatives play an important role in treatment. Etiologically, dolichosigma is divided into congenital and acquired. Congenital dolichosigma may have a hereditary predisposition. In addition, with the development of this pathology, scientists note the importance of the influence of poor ecology and infectious diseases of the mother during pregnancy.

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Encyclopedia - Intestines

The length of the intestine in a living person is about 5–6 m, of which 3.5–4 m is in the initial section immediately after the stomach, the small intestine, and 1.5–2 m in the final section, the large intestine, which opens anus into the external environment (Fig. 1).

Small intestine: structure and functions

Rice. 1. The alimentary canal and the duration of the process of individual stages of digestion: mouth (1 minute); esophagus (2–3 seconds); stomach (2–4 hours); small intestine (1–4 hours); colon (10 hours to several days)

The human small intestine is divided into 3 parts - duodenum, jejunum and ileum - and occupies the middle section of the abdominal cavity, forming a large number of loops. In the small intestine after the stomach, the digestion process continues and intensive absorption of digested substances occurs.

The duodenum (about 30 cm long) originates from the stomach and goes around the head of the pancreas in the form of a horseshoe. The ducts of the liver (see No. 5 of the magazine for 2005) and the pancreas open into its lumen. In the duodenum, acidic food gruel (chyme) coming from the stomach is mixed with alkaline juices of the pancreas, liver (bile) and intestinal glands. The flow of food gruel from the stomach reflexively stops as soon as the alkaline reaction in the duodenum changes to acidic. Under the influence of enzymes of intestinal, pancreatic juices and bile in the duodenum, nutrients are broken down into simpler components and their absorption begins. In the jejunum and ileum (there is no clear boundary between them), chemical processing of food and absorption of digestion products continue, as well as mechanical mixing and movement of food gruel towards the large intestine.

The diameter of the small intestine does not exceed 5 cm, and its wall is formed by 3 membranes. The inner (mucous) membrane has a large number of circular folds, especially well developed in the duodenum. Numerous intestinal villi (about 2500 per 1 cm2) increase the absorption surface of the mucous membrane. In the center of the villus there is a lymphatic capillary, and along the periphery there is a network of blood capillaries (Fig. 2). Digested proteins enter the blood capillaries, and fats enter the lymphatic capillaries, which are absorbed through the epithelium of the mucous membrane of the small intestine. The huge number of microvilli on the surface of the villi facing the intestinal lumen increases the surface area of ​​the small intestine by another 30–40 times. Due to the presence of folds of the mucous membrane, villi and microvilli, the absorption surface of the small intestine in humans reaches 200 m2.

Rice. 2. Intestinal villi: serosa, muscularis, submucosa, mucosa, epithelial cells, villi, blood capillaries, lymphatic capillary

In the thickness of the mucous membrane of the small intestine there are numerous small tubular glands that secrete intestinal juice. The mouths of these glands open into the gaps between the villi. During the day, a person secretes up to 2.5 liters of intestinal juice; its numerous enzymes break down proteins, fats and carbohydrates in food. In this case, directly in the cavity of the small intestine, under the influence of enzymes of intestinal, pancreatic juices and bile, the breakdown of nutrients occurs only into individual fragments. The final cleavage occurs on the surface of the microvilli of the intestinal epithelium. This is the so-called parietal, or membrane, digestion, which occurs due to its own digestive enzymes produced by microvilli. When digested, food substances lose many properties, including harmful ones. From absorbed substances in organs and tissues, complex compounds specific to the human body are synthesized again.

Along the course of the small intestine, special protective formations in the form of single and group lymphoid nodules are also scattered in its mucous membrane. Groups of nodules (called Peyer's patches) are found only in the ileum. Lymphoid nodules provide protection to the body from harmful foreign substances found in food. The number of lymphoid nodules is greatest in children and decreases with age.

The epithelial cells lining the lining of the small intestine quickly wear out and die. The average lifespan of intestinal epithelial cells is 3–5 days. Replacement of dead cells occurs due to the proliferation of new ones. The process of regeneration of the intestinal epithelium occurs continuously at a rate of 1 million cells per minute.

The muscular layer of the small intestine consists of an inner circular and outer longitudinal layer involuntary muscles. Due to their contractions, wave-like peristaltic movements of the small intestine are carried out, promoting the movement of its contents towards the large intestine. Pendulum-like movements of the muscular membrane ensure mixing of the food gruel. Sometimes, when poor quality food is ingested, antiperistaltic movements of the muscle membrane may occur. In this case, the contents of the initial sections of the small intestine are returned to the stomach and, together with its contents, are expelled through the esophagus into the oral cavity. Vomiting occurs, which begins as a result of stimulation of the gag reflex center in the medulla oblongata and is accompanied by a strong contraction of the abdominal muscles and diaphragm.

Nota Bene!

Intestinal peristalsis and its secretory activity are enhanced by mechanical action on the mucous membrane, for example, rough food, under the influence of certain salts, acids and alkalis, as well as the products of the breakdown of fats and individual hormones absorbed into the blood. They give a similar effect spicy seasonings and special nutritional supplements.

The jejunum and ileum, outward from the muscular coat, are covered with a special, very smooth serous membrane - the peritoneum, which allows them to easily slide against the walls of the abdominal cavity. When the peritoneum passes from the small intestine to the posterior wall of the abdominal cavity, a two-layer mesentery is formed, which does not interfere with peristalsis, but maintains the position of the intestine. In this case, the loops of the jejunum are located in the abdominal cavity mainly on the left (in the projection from the navel), and the loops of the ileum are located on the right and below. In the thickness of the mesentery, vessels and nerves approach the intestine. During meals, blood flow in the vessels of the small intestine increases several times, which promotes the digestion process.

At the junction of the small intestine and the large intestine, there is a special valve that allows the contents of the small intestine to flow into the large intestine in small portions, but prevents the contents of the large intestine from returning back.

Large intestine: structure and functions

Rice. 3. Large intestine: Haustra, Ascending colon, Caecum, Vermiform appendix, Transverse colon, Rectum, Sigmoid colon, Descending colon, Longitudinal muscle band,

The large intestine is the section of the digestive canal in which the digestive processes are completed and feces are formed. Here, water is absorbed (up to 4 liters per day) and the processes of fermentation and decay of undigested food substances take place.

In the large intestine, there is a cecum with a vermiform appendix, a colon, consisting of the ascending, transverse, descending, sigmoid colon, and the rectum (Fig. 3). The large intestine differs from the small intestine in its larger diameter (4–7 cm), the presence of three longitudinal muscle bands on the surface, between which swellings and haustra are formed, as well as peculiar “suspensions” located along the muscle bands, filled with fat - omental processes. The mucous membrane of the colon is devoid of villi, but it has many crescent-shaped folds, a large number of intestinal glands that produce mucus, and only single lymphoid nodules.

The cecum is located in the right iliac fossa, has a saccular shape and a width of 7–8 cm. A vermiform appendix (appendix) extends from the posterior wall of the cecum, in the mucous membrane of which there is large cluster lymphoid nodules, which is one of the reasons for its frequent inflammation. Next, after the cecum, comes the colon, which is located in the form of a “frame” around the loops of the small intestine. In the left iliac fossa it forms a loop - the sigmoid colon. The large intestine ends with the rectum, which lies in the pelvic cavity. The bladder is located in front of the rectum in men. seminal vesicles And prostate, in women - the uterus and vagina. The condition of the rectum can affect the condition of nearby organs. Regular emptying of the rectum contributes to their normal functioning.

Rice. 4. Rectum: Ampulla, External anal sphincter, Anal canal, Internal anal sphincter,

middle part the rectum is expanded in the form of an ampoule in which feces accumulate (Fig. 4). When filled, the diameter of the ampoule can increase to 30–40 cm. The lower part of the rectum is called the anal canal; it passes through the pelvic floor and ends at the anus. The mucous membrane of the anal canal has a number of longitudinal folds, between which mucus accumulates, facilitating the act of defecation. In the thickness of the mucous membrane of the anus there are a large number of veins that form the hemorrhoidal plexus. A number of medicinal substances introduced into the rectum are well absorbed into the veins of this plexus, then they enter the general bloodstream, bypassing the liver. This circumstance is important when taking medications that are destroyed in the liver. Inflammation of the veins of the hemorrhoidal plexus leads to a painful disease - hemorrhoids.

In the area of ​​the anus, the fibers of the circular layer of the muscular layer form a thickening - the internal sphincter of the anus; it opens involuntarily. Directly under the skin lies the external sphincter, formed by skeletal muscles pelvic floor; its activities are consciously controlled by man. Both sphincters open during the act of defecation, the reflex center of which is located in sacral region spinal cord. Control over the center of defecation from the cerebral cortex is established in a child from about two years of age.

During digestion, 0.5–1 liters of food gruel passes from the small intestine to the large intestine, which is exposed to bacteria inhabiting the large intestine. Among them, bifidobacteria, lactobacilli, and Escherichia coli predominate. These microorganisms play an important role: some of them cause the fermentation of fiber, others cause the rotting of protein and the breakdown of bile pigments. A number of bacteria synthesize vitamins (K, E, B6, B12). Fiber hydrolysis products, minerals and vitamins, together with water, are absorbed into the blood and used by the body. During the breakdown of proteins, toxic substances indole, skatole, phenol, etc. are released; some of them are absorbed into the blood, enter the liver and are neutralized there, most of excreted from the body with feces. It is very important to maintain a balance between the processes of fermentation and decay, because as a result of fermentation in the large intestine, acidic environment, preventing excessive rotting. Normal intestinal microflora suppresses the activity of pathogenic microbes and promotes the body's production of natural protective factors.

Microflora appears in the intestines of a newborn from the first hours of life due to feeding breast milk. By the end of the first week of life, a baby has up to 1010 microbes in 1 g of feces, mainly bifidobacteria and lactobacilli. When artificially feeding newborns, the formation intestinal microflora progresses more slowly and dysbacteriosis may develop. It should be remembered that acute intestinal infections and the use of certain medications (primarily antibiotics) also lead to the death of the natural microflora of the colon. When the normal bacterial composition is disrupted, active proliferation of fungi occurs. In this case, an increase in the number of beneficial microorganisms in the intestines will be facilitated by a special diet or taking special medications prescribed by a doctor. bacterial preparations.

Peristaltic movements of the colon move its contents towards the rectum. This content may be retained in the haustra of the colon, which facilitates the absorption of water and the formation of feces. Some sulfuric acid salts have a laxative effect, because... prevent the absorption of water in the colon and enhance its peristalsis. These chemical compounds are used in the manufacture of laxatives medicines.

Filling of the rectum with feces and stretching of its walls, during which the pressure inside the intestine can increase to 40–50 mm Hg. Art., cause the urge to defecate. The act of defecation is carried out due to the contraction of the muscular lining of the rectum and the relaxation of involuntary and voluntary sphincters anus, which occurs under the control of the cerebral cortex. Straining also occurs consciously: an increase in intra-abdominal pressure due to tension in the abdominal muscles. In older people, the muscular lining of the colon loses its activity, which leads to weakened motility - colon atony. Therefore, older people often suffer from constipation. Help in this situation special diets, enemas and laxatives.

During a day, with normal nutrition, an adult excretes 150–200 g of feces, consisting of 75–80% water. 20–25% of the solid residue contains fiber, bacteria, insoluble salts, a small amount of fat, fermentation and decay products, and some other substances. In addition, in a healthy person, 300–350 cm3 of gaseous substances are formed in the intestines during the day.

Flax seeds for colon cleansing with kefir

Guts. The large intestine includes the sections: cecum, colon (which consists of the ascending colon, transverse colon, descending colon and sigmoid colon) and rectum. The small and large intestines are separated by the ileocecal valve. The appendix arises from the cecum.

The beginning and end of the small intestine are fixed by the root of the mesentery to the posterior wall of the abdominal cavity. The rest of the mesentery ensures its mobility and position in the form of loops. They are bordered on three sides by the colon. Above is the transverse colon, on the right is the ascending colon, on the left is the descending colon. The intestinal loops in the abdominal cavity are located in several layers, the superficial layer is in contact with the greater omentum and the anterior abdominal wall, the deep layer is adjacent to the posterior wall.

The large intestine begins at the ileocecal junction and ends at the rectum and anus (anus). The ileocecal region is located in the right iliac fossa and is the junction of the small intestine with the first section of the large intestine - the cecum. The place of transition of the ascending colon into the transverse colon is the hepatic curvature, and the place of transition of the transverse colon into the descending colon is the splenic curvature.

The cecum is located below the upper edge of the ileum and is covered by peritoneum on all sides. Where the cecum does not have complete peritoneal cover, its posterior wall is tightly fixed to the retroperitoneal tissue and iliac fascia. At the base of the appendix, all three muscle bands of the cecum converge. It is also covered on all sides by peritoneum. The ascending colon is located mesoperitoneally. Its right bend is in contact with the lower surface of the right lobe of the liver, the bottom of the gallbladder, and is located intraperitoneally or mesoperitoneally. The transverse colon is located intraperitoneally, begins in the right hypochondrium, passes into the epigastric and umbilical regions itself, and then reaches the left hypochondrium, where it passes into the left bend, located intraperitoneally. The transverse colon borders on top with the liver, gall bladder, greater curvature of the stomach and spleen, below - with loops of the small intestine, in front - with the anterior abdominal wall, behind - with the duodenum, pancreas and left kidney, which are separated from it by the mesentery and parietal peritoneum. The descending colon is located mesoperitoneally. It is separated from the anterior abdominal wall by loops of the small intestine and the greater omentum; behind it are the muscles of the posterior abdominal wall. The sigmoid colon is located intraperitoneally and has significant mobility.

Intestinal mass " conditional person"(with a body weight of 70 kg) the norm is 1 kg. The thickness of the intestinal wall (except for the rectum) is 2–3 mm, during contraction it is 4–5 mm, the thickness of the rectal wall is 2.4–8 mm. The residence time of the contents (chyme and feces) in the intestines is normal - about 30 hours.

The structure of the intestinal wall

The intestinal wall consists of four membranes:

• mucous membrane, divided into three layers:
• epithelial
• lamina propria, which has depressions - Lieberkühn's glands (intestinal crypts)
• muscle plate
• submucosa, formed by connective tissue, blood vessels and nerves; in the submucosa, on the side of the muscular layer, there is the Meissner nerve plexus; in the submucosa of the proximal duodenum there are duodenal glands that secrete enterokinase, amylase, peptidases, urogastrone, mucus; the submucosa of the colon is rich in collagen and reticular connective fibers
• muscular membrane, consisting of an internal circular layer (in which, despite the name, the muscle fibers run obliquely) and an external longitudinal layer of smooth muscle; the longitudinal layer in the small intestine is continuous, and in the large intestine (with the exception of the rectum) it goes into the form of three longitudinal tapes 3–5 mm wide; between the circular and longitudinal layers is the Auerbach nerve plexus;
• serous membrane, which is a visceral layer of the peritoneum, consisting of dense connective tissue and covered on the outside with flat epithelium; The serous membrane of the colon has omental processes 4–5 cm long, filled with fatty tissue.

Intestinal microflora

I.I. Mechnikov, 1907

The intestinal microflora consists of two closely interacting groups of microorganisms: intracavitary and parietal. In the duodenum, microflora is practically absent due to the need to overcome the acidic environment of the stomach, as well as due to the bactericidal properties of bile. In the cavity of the proximal parts of the small intestine there is normally a relatively small number of microorganisms - less than 10 4 -10 5 in 1 ml, mainly gram-positive microflora: bifidobacteria, staphylococci, streptococci, lactic acid bacteria, enterococci (enterococcus fecal, enterococcus faecium, enterococcus gilvus and enterococcus pallens) and fungi. The vital activity of the human intestinal microflora consumes up to 10% of incoming energy and 20% of the volume of food taken.

With drug or surgical suppression of gastric acid production, or its reduction in hypoacid and anacid gastritis and similar conditions, colonization of the proximal parts of the small intestine occurs with microflora.

In the distal parts of the small intestine, the number of microorganisms increases, mainly due to an increase in their density directly on the mucous membrane, and not in the lumen; number of aerobic and anaerobic bacteria becomes equal. The main barrier to the penetration of microorganisms from the colon is the normally functioning ileocecal valve. In addition, the number of actinomycetes and related microorganisms, which synthesize a number of vitamins and substances that increase the resistance of normal microflora, is increasing.

The large intestine, to a much greater extent than the small intestine, is populated by various microorganisms, the number of species of which exceeds 500. In the large intestine, microorganisms make up 30% of the dry mass of the luminal contents. The most common and physiologically significant are anaerobes: bifidobacteria, lactobacilli (they are represented by the following species: Lactobacillus acidophilus, Lactobacillus casei, Lactobacillus bulgaricus, Lactobacillus plantarum, Lactobacillus salivarius, Lactobacillus reuteri, Lactobacillus rhamnosus etc.), bacteroides, fusobacteria, veillonella, eubacteria, peptostreptococci, clostridia ( Clostridium difficile, Clostridium perfringens and etc.), Eggerthella lenta and aerobes and conditional anaerobes: Escherichia coli, lactose-negative enterobacteria, Proteus ( Proteus mirabilis, Proteus vulgaris etc.), Enterobacter ( Enterobacter cloacae etc.), Citrobacter, as well as enterococci, staphylococci, Klebsiella (mainly Klebsiella pneumoniae), yeast-like fungi. The number of microorganisms increases towards the distal parts of the colon, more in the luminal rather than in the parietal zones (Dobrovolsky O.V., Serebrova S.Yu.). Bacteria are found in the intestines of a healthy person Akkermansia muciniphila(make up about 3-5% of the total microbiota), Christensenella minuta(about 1% of the total microbiota), Faecalibacterium prausnitzii, Gemmiger, Acidaminococcus, Anaerovibrio, Megasphaera, Ruminococcus, Butyrivibrio, Lachnospira, Coprococcus and others.

Until birth, the fetal gastrointestinal tract is sterile. During birth, the newborn colonizes the digestive tract through the mouth, passing through the mother's birth canal. Bacteria Escherichia coli and streptococci can be found in the digestive tract of a newborn several hours after birth, and they spread from the mouth to the anus. Various strains of bifidobacteria and bacteroides appear in the gastrointestinal tract 10 days after birth. Children born by caesarean section have significantly more low content lactobacilli than emerging naturally. Only in children who are fed breast milk do bifidobacteria predominate in the intestinal microflora, which is associated with a lower risk of developing infectious diseases of the gastrointestinal tract (

The intestine is the part of the digestive system that begins with the duodenum and ends with the anus. The intestine is a structure in which various processes occur that carry out the digestion and absorption of nutrients. At the same time, the mucous membrane produces a number of biologically active compounds necessary for the physiological breakdown of products. This article will tell you everything about the structure, physiology, function, pathology and diagnosis of the human intestine.

3D intestinal model

Anatomy

How many meters is the intestine of an adult human? Structurally and anatomically, the intestine can be divided into a small and thick section. The total length of the intestine in an adult is from 3.2 to 4.7 m. Length thin section can range from 1.7 to 4.2 m. In women, the length of the small intestine is shorter than in men. In the initial part, the length of the small intestine is 50 mm, in the transition section the diameter reaches 30 mm.

The small intestine is divided into several sections:

• Duodenum;
• Skinny;
• Ileum.

The last two are located intraperitoneally, they are mobile and contain a mesentery, which contains blood vessels and nerves.

The large intestine reaches a length of 1.5 m. In the proximal section its diameter is 10-14 cm, and in the distal section it is 5-6 cm. Anatomically it is divided into 6 parts:

• Blind;
• Rising;
• Transverse;
• Descending;
• Sigmoid;
• Straight.

From the cecum of the intestine extends a collection of lymphoid tissue called the appendix or appendix. This organ structure, according to many scientists, plays an important role in the immune response when foreign microorganisms enter. The place where the ascending colon passes into the transverse is called the hepatic angle, and the transition to the descending part is called the splenic angle.

The blood supply to the intestines comes from the upper and inferior artery mesentery. Venous outflow is carried out by the veins of the same name, which then enter the venae portae. Innervation of the intestine comes from different sources depending on the type of excitation. Sensory fibers arise from the spinal roots and vagus nerve, motor from parasympathetic and sympathetic nerves.

Assessing the structure of the intestine, we can say that it is divided into four layers:

• Serous;
• Muscular;
• Submucosal;
• Slimy.

Each layer of the intestine has its own function that takes part in the digestion process. The mucous layer consists of epithelial cells that form villi necessary to increase the absorption surface area. A number of nutrient cells are capable of synthesizing a special intestinal secretion, which is necessary to activate the digestive processes and improve the processing of the food bolus.

In the large intestine, the mucosa is devoid of villi. In this area, active absorption of nutrients does not occur, but liquid absorption begins through the inner wall. The large intestine is necessary for the proper formation of feces. Along the entire intestinal wall there are accumulations of lymphoid tissue that take part in the immune response. The muscle layer is represented by circular and longitudinal muscle fibers, which are necessary to move the food bolus along the intestinal canal.

Physiology

The process of digestion of foods begins in the oral cavity. To facilitate digestion, food must be chewed thoroughly. After this, the food bolus enters the esophagus, stomach, and then into the initial section of the small intestine - duodenum. Pancreatic excretion and hepatic bile exit into the duodenum through the papilla of Vater. These liquids have a direct impact on the processing of complex and simple molecules. Under the influence of bile and pancreatic enzymes, complex biological polymers are broken down into monomers. Further digestion takes place on the inner wall of other parts of the intestine.

Thanks to the movements of the muscle layer, it is possible to evenly distribute nutrients along the inner wall of the intestine, which greatly enhances the absorption process. The process of absorption of nutrients through the layer of epithelial cells is carried out according to the type of active transport against a concentration gradient. This means that to saturate with nutritional molecules it is necessary to expend some of your own energy.

In addition to digestion, the intestines perform a number of additional functions:

• Endocrine function. Intestinal cells synthesize peptide hormones that have a great influence on the regulation of the intestines and other organs of the human body. The maximum number of epithelial cells of this kind is located in the duodenum.
• Immune. Immunoglobulins, or antibodies, are special proteins involved in the humoral type of immune response. Their synthesis is carried out in the red bone marrow, spleen, lymph nodes, bronchi and intestines.

In addition, the intestines contain special microflora that help in the digestion of certain foods and the synthesis of vitamins.

Diagnostics

To find out the cause of intestinal disease, it is necessary to use physical, laboratory and instrumental research methods. Interviewing the patient is of particular importance. When talking with a patient, the doctor needs to clarify the nature of the complaints, the duration of the disease, their onset, the dependence of symptoms on the time of day and other little things that are of great value when making a diagnosis. Most often, patients seek help when they experience pain associated with eating or defecation.

Patients are concerned about bowel dysfunction, manifested in the form of prolonged constipation or frequent diarrhea. With organic pathology affecting the intestinal wall, impurities of mucus and/or blood are found in the stool. Very often, diarrhea occurs due to the consumption of specific foods. For this reason, it is important to interview the patient to find out the nature of their diet and eating habits. In the future, this will allow you to associate symptoms with the type of diet and foods that cause stool upset.

It is advisable to immediately examine the patient to assess his physique, skin color and visible mucous membranes. Disease of the small intestine leads to weight loss, pallor skin, hair loss and brittle nails. Pay attention to the abdomen, its shape and peristalsis. Palpation is of great value in the study of intestinal diseases. Knowing the projections of organs onto the abdominal wall, it is possible to establish the localization of the pathological process. If there is pain in the left iliac region, problems with the sigmoid region are suspected, and if there is pain in the right iliac region, then this is usually the cecum. Pain in other areas is determined in a similar way.

It must be said that only the large intestine and the distal part of the small intestine are amenable to the palpation method of examination. Thanks to palpation, you can determine the size, tenderness, shape and mobility of the colon. Auscultation can evaluate peristalsis, hear the sound of splashing, rumbling, and transfusion. If a neoplasm is suspected in the distal parts of the digestive tract, it is necessary to conduct a digital examination of the rectum. To do this, the patient lies on his left side and bends his legs under him. Then the doctor puts on a glove and lubricates forefinger lubricant. When assessing the contents of the rectum, blood may be detected, which will indicate the presence of hemorrhoids, fissures or rectal cancer.

Laboratory tests

There are many functional tests, thanks to which it is possible to establish the function of the human intestine. To establish the level of absorption of nutrients, a lactose loading test is used. By increasing the concentration of sugar in the blood, we can talk about the state of activity of intestinal enzymes. To more accurately assess the condition of the inner intestinal wall, a biopsy is used - a technique consisting of collecting biological material for further histological examination. To assess absorption, you can use monomers of nutrients that enter the blood plasma unchanged.

To study the peristaltic function of the intestine, the electrical activity of the intestine is assessed, and the internal pressure of the digestive tract is measured. Indirectly, one can judge motor activity by assessing the speed of movement of the contrast solution administered during an x-ray examination.

Radiography has a very great importance in the diagnosis of diseases of the digestive tract. This type of study can be performed with or without the use of a contrast solution. In the first case, it is possible to detect obstruction of the digestive canal and the contours of neoplasms. I prefer to use a suspension of barium sulfate as a contrast solution. This liquid does not transmit x-rays well, is not absorbed into the blood and is not toxic to the body. During irrigoscopy, a contrast solution is administered through the rectum; this technique allows you to assess the condition, contour and integrity of the inner wall of the large intestine. The method is very convenient for diagnosing diverticulosis, megacolon, dolichosigma and various neoplasms.

Examination of the colon using a contrast solution

Non-contrast research methods are indispensable if perforation of the intestinal wall is suspected. Thanks to x-rays, it is possible to record free gas in the abdominal cavity, which normally should not be there.

Endoscopic methods are very convenient, because thanks to them it is possible to determine the presence of pathological neoplasms and perform a number of simple therapeutic procedures. Endoscopy is a technique based on the use of a fiber optic cable that allows you to display an image of the digestive tract cavity on a monitor screen. An endoscope is a special device that allows you to determine the location of a tumor, diverticulum, ulcer and other disorders of the intestinal wall.

Endoscopic photo of the intestines (Rectum)

Diseases

Very often, when visiting a doctor for medical help, patients complain of diarrhea. In diseases of the small intestine, stool is abundant and contains impurities in the form of undigested particles of fat or muscle fibers. The pathology of the large intestine is characterized by scanty but frequent excretion of feces containing streaks of blood or mucus.

The information given in the text is not a guide to action. To obtain detailed information about your disease, you should contact a specialist.

Impaired stool passage is caused by excessive muscle activity of the intestines or lack of tone. Functional obstruction may be associated with a lack of coordinated peristaltic movements. In this case, feces cannot pass further through the intestinal tract. At long-term illnesses in the digestive tract, atony of the muscular layer of the intestine may occur. This process leads to suppression of peristaltic activity, which is expressed by stagnation of feces. In this case, stool retention reaches 3 or more days.

Painful sensations in abdominal area, usually caused by increased pressure inside the digestive canal. This may be caused by a violation of the passage of gases, stool retention, or convulsive contractions of the intestines. With thrombosis of mesenteric vessels, the pain syndrome is caused by intestinal ischemia, which develops into necrosis if emergency medical care is not provided. At inflammatory diseases pain is associated with irritation of nerve endings located deep in the intestinal wall. The nature of the pain indicates in favor of a particular disease. For example, if the pain is nagging, prolonged, bursting, then this speaks in favor of flatulence and increased gas formation. If the pain is periodic, stabbing, and spastic in nature, then intestinal colic can be assumed. If the sigmoid or rectum is affected, then such diseases are characterized by the appearance of tenesmus (painful, false urge to defecate).

When the small intestine is involved in the pathological process, a deficiency of nutrients in the body develops. The small intestine plays a very important role in the breakdown of foods and the absorption of proteins, lipids, and carbohydrates. Insufficient digestion syndrome is manifested by weight loss, hypovitaminosis, general weakness, increased fatigue, stool disorder and dyspepsia. Most diseases are accompanied by a combination of several symptoms.

Atresia

This condition is caused by congenital or acquired during life closure of the lumen or natural openings of the intestine. Atresia is a common condition, affecting 1 in 1,500 newborns. The vast majority of adhesions occur in the small intestine. The leading causes of the development of congenital atresia are considered to be intrauterine diseases, the influence negative factors environment during pregnancy and poor heredity.

Stenosis

Stenosis is a pathological narrowing of the intestinal lumen. About 60% of all cases occur in the duodenum. Unlike atresia, with stenosis the lumen is not completely blocked and the digestive canal remains undivided. There are congenital and acquired duodenal stenosis. Acquired is more common in middle-aged men who suffer from duodenal ulcer.

Megacolon

A disease in which morphological changes occur in the large intestine, leading to its abnormal expansion, loss of peristalsis and impaired passage of feces. Etiologically, there are two forms of pathology – primary and secondary. Hirschsprung's disease is a primary megacolon associated with the congenital absence of nerve ganglia in the colon. Secondary megacolon is associated with acquired pathology, which can be neurogenic, endocrine or mechanical in nature. Symptomatically, all this is expressed in the form of prolonged constipation, flatulence and abdominal pain. With this pathology, in a sick person, the length of the intestine will, as a rule, increase due to the sigmoid region (dolichosigma).