In a living person it 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 with the 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 - the 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. Internal (mucous) membrane has a large number of circular folds, especially well developed in the duodenum. Numerous factors serve to increase the absorption surface of the mucous membrane. intestinal villi(about 2500 per 1 cm2). In the center of the villus passes lymphatic capillary, and on the periphery - the network blood capillaries(Fig. 2). Digested proteins enter the blood capillaries, and fats enter the lymphatic capillaries, which are absorbed through the epithelium mucous membrane small intestine. A huge number of microvilli on the surface of the villi facing the intestinal lumen increases the surface 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.
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.
Epithelial cells, lining the mucous membrane 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.
Muscularis The small intestine consists of an inner circular and outer longitudinal layer of 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. Spicy seasonings and special food additives give a similar effect.
The jejunum and ileum outward from the muscular membrane are covered with a special, very smooth serosa- the peritoneum, which allows them to slide easily 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
Colon- 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 they secrete cecum with a vermiform appendix, colon, consisting of ascending, transverse, descending, sigmoid colon, And rectum(Fig. 3). The large intestine differs from the small intestine in its large diameter (4-7 cm), the presence of three longitudinal muscle bands on the surface between which swellings form, haustra, 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 a large accumulation of 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 colon ends rectum lying in the pelvic cavity. In front of the rectum in men are the bladder, seminal vesicles and prostate gland, 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.
The middle part of the rectum is dilated in the form ampoules, in which feces accumulate (Fig. 4). The diameter of the ampoule when filled can increase to 30-40 cm. The lower part of the rectum is called the anus (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 - internal anal sphincter; it opens involuntarily. Lies directly under the skin external sphincter, formed by the skeletal muscles of the 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 the sacral part of the 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 enters the large intestine from the small 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 them are 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, an acidic environment is created in the large intestine, which prevents 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 thanks to breastfeeding. 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 of intestinal microflora proceeds more slowly and dysbiosis 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 bacterial preparations prescribed by a doctor.
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 laxative drugs.
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 the involuntary and voluntary sphincters of the 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. Special diets, enemas and laxatives help in this situation.
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.
Normal intestinal function is necessary for the full functioning of the human body. Age, living and working conditions dictate their requirements for the diet and products consumed. On our website you can always find useful information about the properties of food products and recommendations for their best use.
Colon- This is the part of the digestive system in which the digestion process ends and undigested residues are excreted. The large intestine begins from the ileocecal angle (the transition of the ileum to the cecum) and ends with the anus. The Bauginian valve, located at the beginning, allows the food bolus to pass in only one direction.
The large intestine consists of the cecum, colon and rectum, each of which has its own characteristics.
Cecum
This is the beginning of the large intestine, which gets its name from the fact that one end is impassable. In a calm state, the cecum looks like a small sac. Dimensions: vertical 6 cm, transverse from 7.5 cm to 14 cm. The cecum is surrounded by peritoneum on three or all sides. 
5 cm below (the bauginian valve) it adjoins in the form of a narrow tube having different individual lengths and curvature. The appendix can be located either in the right iliac fossa or descend into the small pelvis. The appendix is a collection of lymphoid tissue in which digestive bacteria multiply.
Colon
After the cecum, at the level of the liver, spleen and pelvis, passes the colon, which has 4 sections according to the bends:
- ascending;
- transverse;
- descending;
- sigmoid.
The colon encircles the abdominal cavity. The ascending section is located on the right, goes vertically up to the level of the liver. In the right region, at the lower edge of the last rib, the intestine forms the hepatic angle, then goes horizontally, forming a transverse section. In the left hypochondrium near the spleen, the intestine bends again, then the sigmoid section begins.
The total length of the colon is about one and a half meters; it is separated from the cecum by the Busi sphincter. In everyday life, the place of transition of the ascending to the transverse is called the hepatic angle, and the transverse to the descending is called the splenic angle. The splenic angle is acute, fixed by the diaphragmatic-colic ligament. 
The sigmoid section occupies the left iliac fossa and is assembled into two loops. The junctions of the intestinal sections are fixed by the mesentery or fold of the peritoneum, consisting of two layers.
Rectum
From the sigmoid colon to the anus there is a rectum, forming an ampulla or extension in the initial section. The name reflects the anatomical structure - there are no bends in the intestine.
The diameter of the rectum is from 4 to 6 cm, the location is the small pelvis. The rectum ends with two anal sphincters - internal and external. The section is replete with nerve endings and is a reflexogenic zone. The act of defecation is a complex reflex controlled by the cerebral cortex. 
Structure of the intestinal wall
The wall of the colon has the following layers:
- internal mucosa, consisting of epithelium, mucous and muscular plates;
- submucosa;
- muscle layer;
- serous membrane.
The mucous membrane is collected inside the large intestine into deep folds or crypts, due to which the absorption surface increases significantly. The lamina mucosa contains Peyer's patches, or collections of lymphatic tissue in the form of follicles (similar to vesicles). Endocrine L-cells that produce protein hormones are also located here.
The smooth muscles of the intestine are collected in longitudinal and circular bundles. This is necessary for contractions that propel the bolus.
Directly adjacent to the outer serous membrane and in some places adheres to the omentum or accumulation of adipose tissue, covering the intestines from the abdominal wall. 
Functions
The large intestine performs the final digestion of food, participates in the formation of cellular immunity, has an endocrine function, contains special microflora, forms and excretes feces.
Organ diseases
Diseases are divided into several groups:
- motility disorders - weakening or strengthening of peristaltic movements (diarrhea or diarrhea, constipation or constipation with stool retention for more than 3 days);
- inflammation ( and );
- neoplasms ( and );
- congenital developmental defects (diverticula, atresia);
If we consider the structure of the human intestine, its diagram is quite complex. This is a large organ. Depending on the structural features of a person, its length can be 4-8 meters. It plays an important role in human life not only due to the digestion of food. This is an important part of the gastrointestinal tract and an important human organ, without which it is impossible to live fully.
What is the intestine and its features
The intestine is the largest human organ. It represents the gastrointestinal tract in the body, which absorbs and digests food. Its job is to saturate the body with all nutrients and microelements.
The inside of the organ is covered with tiny villi, through which waste products entering the human body pass. Due to their structure, they break down all elements into vitamins, minerals, fats and carbohydrates. The smallest crypts that each villi has give mobility to the intestinal muscles, moving food throughout the gastrointestinal tract.
It is also important to understand what other work the intestines do. This is an organ that directly affects the human immune system. These two concepts are closely related to each other. On the mucous membrane of the organ there is a huge number of befideobacteria and lactobacilli, which help destroy infections and pathogenic microorganisms that have entered the human body. These are the real protectors of humans from disease. They also destroy all toxic substances that enter the body and are harmful to health.
Any malfunction in the gastrointestinal tract can cause problems and various diseases. Proper functioning of the intestines is directly related not only to health, but also to human life expectancy. Minor disturbances trigger pathological processes, causing rapid aging, wear and tear of organs and their diseases.
What is the function of the intestines in human life? First of all, cleaning features from unnecessary slag. Human organs, tissues and cells, feeding on all the necessary microelements, secrete antibodies that leave the body through the gastrointestinal tract. Unnecessary residues are formed into feces and are excreted from the body.
The structure of the intestinal wall
For those who want to know everything about the intestines, its structure, function and anatomical structure, it is important to understand what the structure of the intestinal wall is. The anatomy of the intestine influences the functioning of the digestive system.
The intestine consists of 4 layers, each of which has a huge number of capillaries and arteries. These layers are arranged in order as follows:
- The first layer is the mucosa with an epithelial layer. It contains the Luberkühn glands, which look like small villi with crypts. The muscle plate is also located here.
- Next is the submucosal part. Everything on its surface is connective tissue, where nerves and blood vessels are located. This layer has a complex structure of collagen fibers, nerve plexus, and connective reticular fibers.
- The third section contains the muscular layer. Between it and the submucosa is the Auerbach nerve plexus.
- The last layer consists of connective tissue. This is a serous layer that tightly covers the epithelium, like a protective membrane.
Having figured out what the intestinal wall is made of, you can understand how the intestines are structured, what they look like and how they work. On which side is it vulnerable, and on which side is it more protected from external influences?
Structure of the small intestine
The longest organ is the small intestine. It begins and ends at the beginning of the large intestine. The physiology of the work of this organ lies in various digestive processes. The intestine has a mesentery, which has two parts. It connects the intestines to the abdominal cavity.
This part includes 3 sections, which do not have any partitions between them. Each department has its own zones that perform their functions.
Department of the duodenum
The section of this intestine is the beginning of the organ. The length of the organ is about 30 cm. It is located in the pancreas area. It includes the bile and pancreatic ducts. Therefore this department responsible for the quality digestion of food consumed by humans.
Bile and gastric juice react, affecting food, which breaks down into elements, begins to be absorbed and supplies all the necessary substances.
Section of the jejunum
This section is located at the very top of the small intestine . It got its name because it is always empty, regardless of food intake. Its shell consists of two layers of smooth muscle tissue.
Most often, this section of the small intestine suffers from ascariasis and enteritis. This is where cancerous tumors form.
Aerial part of the intestine
The aerial part of the small intestine is located in the lower half and is completely covered by the peritoneum. The average length is more than 2.5 m. With a large number of vessels and capillaries. For women it may be slightly less. After death, it stretches almost 2 times.
The walls of the aerial section have 2 layers. They actively contract, so they are responsible for peristalsis. The main feature of this department is the production of neurotensin, which affects the drinking and eating reflex.
Structure of the large intestine
The large intestine is the end of the gastrointestinal tract. Its length is approximately 2 m and its diameter is 4-10 cm. Its dimensions can be seen very well in the form of a three-dimensional image, which is shown in the picture during diagnosis. The task of this body is digestion of food, absorption of water and formation of feces.
The intestines include:
1. Blind intestine
This is a worm-like outgrowth, i.e. appendix. Despite the common opinion of ordinary people that it does not play any role in a person’s life, this is a vital department. Thanks to it, the level of activity and development of pathogenic microorganisms decreases. It affects the development of beneficial bacteria in the large intestine. The appendix is directly related to the proper functioning of the human immune system, protecting the body from infections and diseases. This is an important part of the large intestine. It is located on the right side of the abdominal cavity.
Its mucous layer contains the Luberkühn gland, which plays an important role in the human body. When it becomes inflamed, a person is diagnosed with typhlitis. If inflammation lasts for a long time, rapid aging of a person occurs. The roots of malignant tumors also develop here.
2. Colon
The colon is the main part of the small intestine. It does not participate in the work of digestion, in the assimilation, digestion and movement of food. Despite this, it is important for the human body. It is in this section that maximum absorption of water and liquids occurs. If liquid food from the small and large intestines is not completely digested, it enters the colon. From a liquid state it stops in feces.
The following description of characteristics will help you understand the operation. The entire length of this section is 1.5 meters. The diameter, due to the individual characteristics of the body, can be 8 cm. This department consists of subdivisions:
- Ascending, about 20 cm long.
- Transverse colon with a maximum length of up to 56 cm;
- Descending, with a length of up to 22 cm.
Damage to these areas by bacteria and infections leads to diseases such as:
- constipation;
- diarrhea;
- colitis;
- intussusception.
3. Sigmoid colon
- This is an important part of the gastrointestinal tract, since the entire functioning of the large intestine depends on its proper functioning. Any ailment can provoke diseases of the entire gastrointestinal tract. The intestine is located in the right hypochondrium, between the descending and colon. It reaches 70 cm in length and 4 cm in diameter. This section is involved in digestion. It can be compared to a large sponge that absorbs liquids and then distributes them throughout the vital systems.
4. Rectum
Its scientific description is rectum. It is located in the pelvis and ends at the anus. It is small in size: 14-16 cm. In the anal area, the diameter is approximately 4 cm, and higher up the intestine it increases to 7.5 cm. The length of the anal canal ranges from 3-5 cm.
The rectum is a kind of reservoir in which processed food and feces accumulate. Then, with the help of the intestinal muscles, they come out. An important component of this section of the intestine is the diaphragm muscles. They do not allow feces to pass out constantly, keeping them inside the intestine until maximum accumulation.
Video - Structure of the human intestine
Differences
The task of the large intestine is fecal formation. The main task of the small intestine is to absorb all the nutrients the body needs. Even though they are part of the digestive system, The following differences between the intestines can be distinguished:
- diameter of thick - 4-9 cm, thin - 2-4 cm;
- the thick one has a grayish tint, the thin one has a pink tint;
- the thin muscle is smooth and longitudinal, the thick muscle has many growths and protrusions, which are called outgrowths of the intestinal mucosa;
- the thick one has omental processes;
- the thick one has a shell up to 5.5 mm, and the thin one is almost 2 times smaller.
Knowing all these features, you can understand how the human digestive system functions and what each of its departments is responsible for.
The human intestine is one of the most important organs, performing many necessary functions for the normal functioning of the body. Knowing the structure diagram, location of the organ and understanding how the intestines work will help you navigate in the event of first aid, initially diagnose the problem and more clearly perceive information about diseases of the gastrointestinal tract.
A diagram of the human intestine in pictures with inscriptions on the front will make it possible to clearly and easily:
- learn everything about the intestines;
- understand where this organ is located;
- study all sections and structural features of the intestines.
What is the intestine, anatomy
The intestines are one of the most important human organs. The intestine is the human digestive and excretory organ. The three-dimensional image clearly demonstrates the structure diagram: what the human intestine consists of and what it looks like.
It is located in the abdominal space and consists of two segments: thin and thick.
There are two sources of its blood supply:
- Thin- we supply blood from the superior mesenteric artery and the celiac trunk
- Thick- from the superior and inferior mesenteric artery.
The starting point of the intestinal structure is the pylorus of the stomach, and it ends at the anus.
Being in constant activity, the length of the intestine in a living person is about four meters; after death, the muscles relax and provoke its increase in size to eight meters.
The intestines grow along with the human body, changing size, diameter, thickness. So, in a newborn child, its length is about three meters, and the period of intensive growth is the age from five months to five years, when the child moves from breastfeeding to a common “table” and increased portions.
The intestine performs the following functions in the human body:
- Provides the supply of hydrochloric acid to the stomach for the primary processing of food;
- Actively participates in the digestive process, breaking down eaten foods into individual components and taking from them the microelements and water needed by the body;
- Forms and removes feces from the body;
- Has an important effect on the human hormonal and immune systems;
Small intestine and its functions
The diagram clearly demonstrates the location of the small intestine between the stomach and large intestine. The small intestine is responsible for the digestive process, and it is named so because of its comparatively smaller diameter and thinner walls, unlike the large intestine. But in its size it is not inferior to any organ of the gastrointestinal tract, capturing almost the entire lower space of the peritoneum and part of the pelvis.
The overall work of enzymes in the small intestine, gallbladder and pancreas promotes the breakdown of food into individual components. Here, the absorption of vitamins, nutrients, and active components of most medications necessary for the human body takes place.
In addition to digestive and absorption functions, it is responsible for:
- movement of food masses further through the intestines;
- strengthening the immune system;
- hormonal secretion.
This segment is divided according to its structure into three sections: duodenum, jejunum, and ileum.
duodenum
The beginning of the structure of the small intestine opens - the duodenum, stretching behind the pylorus of the stomach, fitting the head and partly the body of the pancreas, thereby forming the shape of a “horseshoe” or semi-ring and flows into the jejunum.
Consists of four parts:
- Upper;
- Descending;
- Lower;
- Rising.
In the middle of the descending part, at the end of the longitudinal fold of the mucous layer, there is the nipple of Vater, which includes the sphincter of Oddi. The flow of bile and digestive juice into the duodenum is regulated by this sphincter, and it is also responsible for preventing the penetration of its contents into the bile and pancreatic ducts.
Skinny
The anatomical structure separating the jejunum and ileum is weakly manifested, but there is still a difference. The ileum, relatively lean, is larger in diameter and has thicker walls. It was called skinny due to the absence of contents in it during the autopsy. The length of the jejunum can reach 180 cm; in men it is longer than in women.
Ileum
The description of the structure of the lower part of the small intestine (diagram above) is as follows: following after the jejunum, the ileum is connected to the upper part of the large intestine through the bauhinian valve; located on the lower right side of the abdominal cavity. The distinguishing properties of the ileum from the jejunum are indicated above. But a common characteristic of these parts of the human intestine is the clear appearance of the mesentery.
Colon
The lower and last segment of the gastrointestinal tract and intestines is the large intestine, which is responsible for the absorption of water and the formation of feces from chyme. The figure shows the location of this section of the intestine: in the abdominal space and the pelvic cavity.
The structural features of the wall of the colon consist of a mucous layer that protects from the inside from the negative effects of digestive enzymes, mechanical injury from solid particles of feces and simplifies its movement to the exit. Human desires are not subject to the work of the intestinal muscles; it is absolutely independent and not controlled by man.
The structure of the intestine starts from the ileocecal valve and ends with the anus. Like the small intestine, it has three anatomical segments with the following names: cecum, colon and rectum.
Blind
The initial section of the human large intestine, located according to the scheme in the right iliac fossa, framed everywhere by the peritoneum, is arranged in the shape of a pouch. From the posterior wall of the cecum stands out its appendage, nothing more than the appendix, a tubular appendage about ten cm in size and one cm in diameter, which performs secondary functions necessary for the human body: it produces amylase, lipase and hormones involved in the work of intestinal sphincters and peristalsis.
Colon
The main part of the large intestine is located according to the structure between the cecum and rectum. At the junction with the cecum, the cecal ascending sphincter is located. The colon is divided into the following segments:
- Ascending;
- Transverse;
- Falling;
- Sigmoid.
Here, water and electrolytes are absorbed in large quantities, as well as the transformation of liquid chyme into hardened, formed feces.
Straight
Located within the pelvis and without torsions, the rectum completes the structure of the large intestine, starting from the sigmoid colon (level of the third sacral vertebra) and ending with the anus (perineal area). This is where feces accumulate, controlled by the two sphincters of the anus (internal and external). A cross-sectional diagram of the intestine demonstrates its division into two sections: narrow (anal canal) and wide (ampullary section).
Parameters and diseases of the intestines
| Intestines and its parts | Parameters (cm) | Diseases | |
|---|---|---|---|
| Length | Diameter | ||
| Small intestine | 350-400 | Proximal 4-6, distal 2-3. | Obstruction, ciliacia, enteritis, colitis, Meckel's diverticulum. |
| duodenum | 21-25 | 42859 | Duodenitis, ulcer |
| Skinny | 90-180 | Jeunit, ulcer, | |
| Ileum | 130-260 | 2.7 | Crohn's disease, terminal ileitis. |
| Colon | 150-200 | 42951 | Atony, cancer, inflammation. |
| Blind | 3-8,5 | 7 | Cancer, appendicitis. |
| Colon | About 150 | From 5 -8 | IBS, aganglionosis, regional enteritis, colitis, constipation and diarrhea, intussusception. |
| Straight | 14-18 | 4-7,5 | Cancer, hemorrhoids. |
The general health of a person depends on the normal functioning of the intestines. This organ is susceptible to various disorders, disorders and inflammations, often due to human fault due to errors in nutrition. Serious pathologies are also no exception - to prevent their development and exacerbation, it is recommended to monitor your health, undergo unscheduled examinations, and lead a healthy lifestyle.
The small intestine has many functions.
The small intestine gets its name due to the presence of a thin wall and a smaller lumen diameter.
The inner mucous part forms folds. The surface of the mucosa is covered with villi. The small intestine performs the functions:
- secretory function is the production of intestinal juice containing enzymes for further digestion of food. Up to 2 liters of juice are released per day. It contains mucus, which protects the walls from acid and creates a favorable environment for the functioning of the organ;
- absorption of split parts is the main part and main function of the organ;
- The endocrine function is for special cells to produce active hormones for the normal functioning of the intestines and all organs of the body. Most of these cells are located in;
- motor function (motor).
In the department, the final absorption of poisons, medicinal components and toxins that enter through the mouth and are not completely decomposed in the stomach is observed.
Sections of the small intestine
The duodenum is a section of the small intestine.
This section of the intestine is in turn divided into three types:
- duodenum;
- jejunum;
- ileum.
The duodenum occupies the first upper section. It is called because its length is equal to the width of twelve fingers (fingers).
The location of the organ changes depending on the position of the person or structural features. For example, when a person is in an upright position, the organ moves to the right, to the lower part.
The upper part of the duodenum connects to the ducts of the pancreas and gallbladder. The jejunum has another name: “hungry” because it is empty when opened. It occupies 2/5 of the whole. Consists of loops, of which there are 7 pieces. The diameter and number of villi in it are greater than in the ileum, and there are fewer lymphatic vessels.
The ileum is separated by a valve from the cecum. This is the upper part of the thick section. The valve allows chyme (processed mass) to pass in portions from the thin part to the thick part, and prevents harmful bacteria from entering the large intestine into the small intestine. When a person does not eat, the valve is closed. After a maximum of 4 minutes, it opens, allowing 15 ml of chyme into the colon every minute.
The upper loops of the ileum are located vertically, and the lower ones are horizontal.
Symptoms of diseases of the small intestine
Bloating is a symptom of small intestinal disease.
All diseases occurring in the thin part have similar symptoms:
- Painful sensations in the navel area.
- Loose, light-colored, foamy stools with a foul odor.
- Feeling of "boiling" in the intestines.
- , heaviness in the stomach.
- Urge to defecate, accompanied by severe pain.
- With severe inflammation, the temperature rises.
- There is rapid fatigue and weakness.
- Weight loss.
- The skin becomes thin and nails become brittle.
- The whites of the eyes turn red, black spots flicker before the eyes. Visual acuity decreases.
- Haunted frequently.
- Joints affected by arthritis are painful and swollen.
Diseases occurring in the small intestine:
- Enteritis occurs after bacteria penetrate into the thin part where they should not be in healthy people, causing. This, in turn, leads to a decrease in the protective properties of the body and disrupts the production of enzymes in the thin section. The motor function of the intestine slows down. There are acute and chronic forms of the disease;
- carbohydrate intolerance - congenital or acquired lack of enzymes responsible for the breakdown of certain dairy products, sugar (lactose intolerance);
- intestinal vascular disease. Three large arteries pass through this organ. The disease is combined with atherosclerosis of the heart, brain, and limbs;
- to an antigen in the form of a foreign protein;
- . They appear very rarely and are mostly benign;
- Celiac disease is a disease that is inherited. Caused by a lack of enzymes that process protein. It, in turn, poisons the cells of the small intestine, disrupting all current processes.
The colon is an important part of the intestines
The colon is very important in the human body.
This part of the intestine is gray in color and thick, as its name suggests. It is 2 m long and 4 to 7 cm wide.
It looks like a corrugated tube with longitudinal ribbons - muscles and transverse deep grooves. Between the grooves there are haustrae (swellings).
The large intestine plays little role in digestion and absorption. The active work of the thick section begins from 5 to 7 am.
Enzymes found in this organ are 200 times less active than enzymes in the small intestine. The department has an intestinal tract that helps the process of digestion and absorption. Its weight is from 3 to 5 kg.
Functions and main parts of the colon
The thick section performs no less important functions than the thin one. The process of absorption occurs in reverse (readsorption). About 95% of electrolytes and water are absorbed. When 2 kg of chyme arrives from the small intestine, 0.2 kg of feces remains after absorption.
- The transfer function is the accumulation, storage of feces and evacuation to the outside through the anus. Feces travel through the large intestine for more than 12 hours;
- excretory function is the regular removal of feces;
- production of mucus by the glands of the inner surface of mucus;
- cellulose breakdown, protein processing by active microorganisms (microflora) living in the organ for further removal of decay.
The thick section consists of three parts:
- colon;
- rectum.
The cecum is the widest area; it has a vermiform appendix, the so-called appendix, which performs a protective function, like tonsils and adenoids. The appendix contains bacteria necessary for the functioning of the large intestine.
The colon has a length of approximately 1.5 m, a diameter of 5-8 cm, absorbs liquid and prepares feces for exit, they become denser.
The rectum is the final section of the large intestine and intestines as a whole. Its function is to accumulate, retain and remove feces. It has two sphincters (muscle layer), internal and external, that hold feces.
What diseases of the colon are there, watch in the video:
Colon diseases
The colon is the most vulnerable to disease.
The colon is the section of the intestine most vulnerable to disease. Often the first symptoms are invisible to a person.
Periodic changes in constipation and flatulence, rumbling and pain in the anus. Over time, the symptoms increase and the condition worsens.
Ulcerative colitis is a chronic stage of disease of the mucous membrane in the colon and rectum. Inflammation begins in the straight section, gradually rising and affecting the entire thick part. Has signs:
- frequent diarrhea is replaced by rare ones;
- rare bleeding, worse with exacerbation, stool mixed with blood;
- the presence of pain in the left side of the abdomen, which subsides after bowel movement;
- weakness, weight loss, decreased performance.
- a rare disease. Inflammation affects the entire digestive system. The reasons have not been studied, but doctors suggest that the disease has two causes:
- infectious;
- an autoimmune cause, when cells begin to attack their organ tissues. It affects not only the mucous membrane, but also the layers of the intestine and blood vessels.
Ischemic colitis occurs when the blood vessels of the organ walls are damaged. There is a violation of blood circulation in the vessels with varicose veins, thrombophlebitis.
Pseudomembranous colitis occurs when clostridia multiply - these are bacteria that can produce a strong poison - botulinum toxin. Appears with long-term use of antibiotics.
- Tumors. Colon cancer ranks first among all cancers. The predominant causes are: poor nutrition, heredity and a sedentary lifestyle.
- Symptoms do not appear for a long time.
- Irritable bowel syndrome (IBS). The result of impaired colon motility.
- colon. This is a strong distension of the intestine, part of it protrudes into the abdominal cavity. Causes: weak intestinal muscle tone, chronic constipation.
Congenital and acquired changes in the structure of the thick section. There are:
- increase in the length of the sigmoid colon;
- an increase (hypertrophy) in the size of the large intestine, part or all of it.
Almost all diseases that develop in the intestines have similar symptoms: abdominal pain lasting up to 6 hours; blood during bowel movements; diarrhea or . Timely consultation with doctors, proper nutrition with a predominance of vegetables and herbs, an active lifestyle without stress, and prevention of intestinal diseases help prevent dangerous complications.
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