The human gastrointestinal tract, part of which is represented by the large intestine, is distinguished by the variety of sections and features of their functioning. Moreover, it is the digestive system, due to regular contact with various irritants, that is most susceptible to the development of various pathologies. However, it is quite difficult to establish what exactly caused the illness. To identify dysfunction in each part of the intestine, a specific research technique is used. This significantly reduces the effectiveness of diagnosing digestive disorders. Often patients also do not pay attention to discomfort V abdominal cavity, which leads to late detection of intestinal diseases. To avoid the development of complications, you should seek medical help when the first symptoms of pathology appear.
The large intestine is a large hollow organ digestive tract. It does a lot important functions, while constantly being in contact with food masses. As a result, the colon is constantly exposed to various harmful factors that can cause deterioration in its functioning. Diseases of this part of the digestive system, according to medical statistics, are the most common today.
The large intestine is the last section gastrointestinal tract. The length of this section ranges from 1.1 to 2-2.7 meters, and the diameter reaches 5-6 cm. It is much wider small intestine, approximately 2.5 times. The lumen of the large intestine narrows closer to the exit from the rectum, which ends in a sphincter that allows for normal voluntary bowel movements.
Features of the structure of the walls of the large intestine
The walls of the colon consist of four layers:
- mucous;
- submucosal;
- muscular;
- serosa.
All these parts of the intestinal wall ensure the normal functioning of the organ and its peristalsis. Normally, the colon produces a fairly large amount of mucus, which helps move chyme through the digestive tract.
Attention! Chyme is a lump formed by food masses, desquamated epithelial cells, acids and enzymes. Chyme forms in the stomach, changing its consistency as it moves through the gastrointestinal tract.
Bowel functions
The large intestine ensures the completion of the movement of chyme through the digestive tract. She communicates with external environment, which determines the specifics of its functions:
- excretory. The main function of the large intestine. Aimed at removing various pathogens and unprocessed substances from the body. This process must occur regularly and without failures, otherwise, due to the abundance of toxins in the digestive tract, poisoning of the body develops. It is in the large intestine that stool is finally formed, which is then excreted from the rectum. Stimulates excretory function next appointment food. After a person eats food, his brain receives a signal that increases intestinal motility and accelerates the movement of chyme towards the anus.
- Digestive. Most of nutrients are absorbed in the small intestine, but some of the components of chyme enter the body from the large intestine: salts, amino acids, fatty acid, monosaccharides, etc.
- Protective. The large intestine contains about three kilograms of beneficial microflora, which not only ensures normal digestion, but also promotes the functioning of the immune system. Disruption of the bacterial balance leads to a decrease in protective function body, increased susceptibility infectious diseases etc.
- Suction. It is in this section of the digestive system that the bulk of the liquid is removed from the feces - more than 50%, which prevents dehydration of the body. Due to this, feces acquire a characteristic consistency and shape.
The large intestine has general functions, while each of its departments also performs its own tasks, determined by the peculiarities of physiology.
Sections of the colon
The large intestine has a rather complex structure and consists of several sections:
- the cecum, which has an appendage - the appendix;
- colon: ascending colon, transverse colon, descending colon, sigmoid colon;
- rectum.
Attention! The lumens of all parts of the large intestine contain a large number of different microorganisms. They form normal intestinal microflora. Bacteria break down various components of chyme and provide the production of vitamins and enzymes. Optimal functioning of all parts of the intestine is the key to proper digestion.
Cecum
The large intestine begins with the blind section, which is localized in the right iliac region. Its shape resembles a pouch, delimited by two sphincters: the ileocecal valve separates the small intestine, and the Gerlach valve prevents digestive products from entering the appendix.
Attention! The appendix is an appendage of the cecum. Its diameter does not exceed 0.6 cm, and its length varies from 2.7 to 12-13 cm.
It is the cecum that is the site of development the largest number various diseases of the large intestine. This is due to both morphological and physiological characteristics of this department. Pain in diseases of the cecum is localized in the right umbilical region or above the ilium.
Colon
The main part of the large intestine is the colon. Its length reaches 1.7 meters, and its diameter is about 5-7 cm. The colon is separated from the blind fragment of the intestine by the Busy valve.
The structure of the colon is divided into four sections:
- ascending colon;
- transverse;
- descending;
- sigma.
The ascending section is not involved in the main process of food digestion, but it ensures the absorption of fluid from the chyme. It is in this fragment of the digestive tract that up to 30-50% of water is removed from the feces. Ascending colon is a continuation of the blind, and its length varies from 11 to 20 cm. This area is located at the posterior wall of the abdominal cavity on the right. If any pathology affects the ascending intestine, then the pain syndrome is localized in the area from the ilium to the hypochondrium.
The ascending section becomes transverse, starting in the hypochondrium on the right. The length of this fragment can be from 40 to 50 cm. In the transverse intestine, liquid is also absorbed from the chyme, as well as the production of the enzyme necessary for the formation of feces. In addition, it is in this section that pathogenic microorganisms are inactivated. When the transverse section is affected, discomfort occurs in the area 2-4 cm above the navel.
The descending colon is about 20 cm long and is located downward from the left hypochondrium. This part of the intestine is involved in the breakdown of fiber and contributes to the further formation of feces. In the left iliac fossa the descending section becomes the sigmoid section. Sigma has a length of up to 55 cm. Due to the characteristics of the topography, pain during various pathologies of this organ can be localized both in the abdomen on the left and radiate to the lower back or sacral region.
Rectum
The rectum is the terminal, that is, the final, section of both the large intestine and the entire digestive tract. This section of the digestive tract is distinguished by its specific structure and functioning.
The rectum is located in the pelvic cavity. Its length does not exceed 15-16 cm, and the distal end ends with a sphincter, which communicates with the external environment.
Attention! In this section of the intestine, the final formation and accumulation of feces occurs immediately before defecation. Due to the peculiarities of physiology, it is the rectum that is most susceptible to various mechanical damage: scratches, cracks, irritation.
Pain due to dysfunction of the rectum is localized in the perineum and anus, and can radiate to the pubic area and genitals.
Video - Three tests for intestinal diseases
Pain syndrome with damage to the large intestine
Many different diseases can cause pain in the large intestine. A number of factors lead to the development of such violations:
- sedentary lifestyle;
- violation eating behavior, including frequent overeating or following a strict diet;
- abuse of spicy, fatty, smoked foods;
- disruption of the digestive system in patients due to advanced age;
- chronic constipation;
- hypotension accompanied by impaired peristalsis;
- constant use of pharmacological drugs.
These factors can cause disturbances in the functioning of both the entire digestive tract and the large intestine separately. At the same time, establish the cause of the appearance pain syndrome usually quite difficult, and almost impossible on your own. In general, dysfunctions of the digestive system can be divided into two main groups:
- inflammatory in nature: colitis, diverticulitis, Crohn's disease, etc.;
- non-inflammatory disorders: atonic constipation, tumor processes, endometriosis, etc.
Diseases of the large intestine can significantly impair the patient's quality of life. To prevent the development of complications, it is necessary to promptly pay attention to the appearance of warning signs pathology.
Ulcerative colitis is an inflammatory lesion of the tissues of the large intestine. The disease has a chronic course and is characterized by fairly frequent relapses. To date, it has not been possible to accurately determine the cause of the development of the pathology, but it is classified as a disorder of autoimmune origin.
Attention! Most often, colitis is detected in people of two age groups: patients 25-45 years old and patients over 55-60 years old.
- acute colitis;
- chronic with periodic exacerbations;
- chronic continuous, in which remission is not observed for 6 months or more.
Clinical picture ulcerative colitis is generally synonymous with other diseases of the large intestine and is manifested by the following symptoms:
- Intense, long-lasting abdominal pain. Their localization largely depends on which part of the colon was affected by the pathological process.
- Diarrhea or constipation. In this case, bloody inclusions may be observed in the feces.
- Signs of intoxication of the body: nausea, cephalalgia, dizziness, drowsiness and lethargy.
Attention! Lack of therapy for colitis can lead to perforation of the intestinal wall and, as a result, massive intestinal bleeding. This condition is life-threatening for the patient.
Colitis therapy should be carried out comprehensively, taking into account the severity and form of the disease. In case of radical damage to the intestine, the patient is indicated for hospitalization.
Therapy for ulcerative colitis
| Drug name | Image | pharmachologic effect |
|---|---|---|
 | Anti-inflammatory and antimicrobial agent | |
 | Anti-inflammatory and cytoprotective effects | |
 | Anti-inflammatory, immunosuppressive effect | |
 | Immunosuppressant |
Crohn's disease
Crohn's disease is also an inflammatory disease. The pathology is manifested by the development of granulomatosis.
Attention! Granulomatosis is the formation of granulomas, that is, nodular-like neoplasms. Similar growths can occur on the skin, mucous membranes, vascular walls, etc.
Unlike nonspecific colitis, Crohn's disease can affect not only the walls of the large intestine, but also the tissues of the small intestine, stomach and esophagus. Depending on the severity of the pathological process, the number of inflammation foci varies from one to several dozen.
Modern medicine has not yet established the cause of the development of this disease. It has been determined that agents with antibiotic action have positive effect, therefore, the bacterial origin of the pathology is assumed.
There are acute and recurrent forms of the disease. Chronic course observed only in patients with a compromised immune system or severe dysfunction of the digestive tract.
The disease manifests itself with a variety of symptoms:
- intense sharp or cutting pain localized in the area of inflammation;
- the appearance of skin rashes;
- rapid reduction in the patient's body weight;
- bloating;
- bowel dysfunction;
- pain during bowel movements, the appearance of fistulas around the anus.
Patients with Crohn's disease are advised to follow a diet with increased content proteins and exclusion of milk and dairy products. In addition, drug treatment is a mandatory part of therapy.
Therapy for Crohn's disease
| Drug name | Image | pharmachologic effect |
|---|---|---|
 | Anti-inflammatory, antibacterial effect | |
 | Decongestant, antihistamine effect– corticosteroid | |
 | Immunosuppressive drug | |
 | Antidiarrheal agent | |
 | Analgesic effect |
Diverticular disease
Diverticular disease manifests itself in two characteristic conditions:
- diverticulosis – pathological process, in which numerous small protrusions, called diverticula, form on the walls of the large intestine;
- Diverticulitis is inflammation of diverticula as a result of infection.
This pathology occurs as a result of excess pressure on the intestinal wall from its contents. Due to the weakness of the intestinal tissues, sagging and protrusions are formed, which may not cause any inconvenience to the patient for a long period of time. Main clinical symptoms develops only if the diverticulum becomes infected.
Attention! The main cause of diverticular disease is constipation. Constipation leads to constant excessive strain on the colon. It has been revealed that the vast majority of patients suffering from diverticulosis consume insufficient amounts of plant fiber and suffer from regular stool disorders.
Diverticulitis is manifested by the following symptoms:
- intense pain;
- nausea;
- persistent defecation problems;
- bad breath;
- feces with undigested food.
It is worth noting the specificity of the pain syndrome with diverticulitis:
- pain syndrome is localized in the lower third of the abdomen on the left;
- pain may persist for 4-7 days or more;
- upon palpation, the pain increases sharply.
Drug treatment of diverticulitis includes several groups of drugs for a complex effect on the pathological process.
Therapy for diverticular disease
| Drug name | Image | pharmachologic effect |
|---|---|---|
 | Antibacterial action | |
 | Prebiotic with laxative effect | |
 | Stimulation of gastrointestinal motility | |
 | Antispasmodic effect | |
 | Analgesic effect |
If there is no effect from conservative therapy the patient requires surgical intervention.
Malignant neoplasms
Neoplasms of the large intestine can be either malignant or benign nature. At the same time, the first group of tumors is characterized by slow growth and does not cause a significant deterioration in the patient’s quality of life.
Carcinomas develop more aggressively, resulting in a characteristic clinical picture cancer:
- attacks of vomiting, admixture of feces in the vomit;
- loss of appetite leading to cachexia;
- lethargy, drowsiness, weakness;
- low-grade fever;
- stool disorders;
- melena - black stool mixed with blood;
- cutting and tearing pain in the area of tumor formation.
The thick gastrointestinal tract is an important part of the digestive system. Pain in this part of the gastrointestinal tract may indicate the development of serious pathologies and require urgent consultation with a specialist.
And its meaning. We will also get acquainted with its anatomical structure, analyze in detail the role of the layers of which it consists, and study the processes of blood supply.
General information about the rectum
The rectum is necessary for the body to accumulate feces. It originates in the area of the promontory, then descends into the pelvic cavity, located in front of the sacrum. This structure forms 2 bends, moving from the front to the back and called the upper and lower. The upper one is convex in the direction of the concavity of the sacrum, and the lower one looks towards the coccyx area. Sometimes it is called perineal.
Upper section and end part
Features of the structure and functions of the rectum depend primarily on its constituent elements, sections, cells and location. One of these components is the upper part of the organ and its terminal part.
The upper section is a kind of ampoule, the diameter of which is usually in the range of 8-16 cm, but this number can increase due, for example, to atony. This formation is located in the pelvic cavity and expands at one end.
The final part is represented by a circle directed downward and backward, and its continuation is located in the anal canal. After passing it ends with a hole. The size of the formed circle varies less than that of the upper section, and corresponds to 5-9 cm. The size of the intestine ranges from 13 to 16 cm, but about 65-85% of it falls on the pelvis, and the remaining centimeters form the anal section.
Structure of the mucous membrane
The functions of the human rectum are largely determined by its mucous membrane. The mucous membrane forms a numerous number of longitudinal folds, which is possible due to its developed submucosa. These folds can easily smooth out due to stretching of the intestinal wall. The anal canal has folds with constant view; there are from eight to ten of them there. These formations have special depressions lying between them, called anal sinuses (clinicians), which are clearly expressed in children. It is the clinicians who accumulate special mucus in themselves, which facilitates the passage of feces through the anal canal. The anal sinuses are also called anal crypts. They most often serve as an entrance door for microorganisms. The tissue layer located between the anus and the sinuses includes a plexus of veins. In addition to the longitudinal folds, upper sections the rectum has transverse folds. These formations are very similar to the semilunar folds of the sigmoid colon.
Description of the muscularis propria
The structure and functions of the rectum also depend and are determined by the muscular layer, which consists of 2 layers, namely: circular and longitudinal. The circular (inner) layer begins to thicken in the upper part of the perineal region. It is in this area that the internal sphincter is formed, which ends at the junction of the skin and the anal canal. The longitudinal layer covers both the anterior and posterior sections of the intestine, equally. In the lower part, the longitudinal fiber begins to intertwine with the muscular fiber, which rises towards the anus, and also often intertwines with the external sphincter.
Thanks to this, we can conclude that the rectum has the features of a conducting section alimentary canal and looks like an esophagus. There are developmental similarities between these structures: both ends of the primary gut undergo a breakthrough of the blind end of the tube during embryogenesis. In the esophagus, this occurs with the pharyngeal membrane, and in the rectum, with the cloacal membrane. Both canals have muscles consisting of two continuous layers.
Topographical information
The functions of the rectum can be described using topographic information. Behind the organ are two sections of the spine, the sacral and coccygeal. And in front of the male representatives, the intestine is adjacent to the seminal vesicles and the rectum of women borders in the anterior section with the posterior vaginal wall and the uterus. It is separated from these structures by a layer formed by connective tissue.
The proper fascia of the rectum and the anterior surface of the sacral and coccygeal spine do not have fascial bridges between them. This simplifies operations to remove the intestine and its fascia, which covers the vessels. Doctors do not have any particular problems with this.
Functions of the rectum. Description
One of the functions of the rectum is to retain food debris that has not had time to be absorbed in the cavity area small intestine, as well as water. A large number of substances enter here organic nature and products that have undergone bacterial rotting, and also contain substances that cannot be digested, for example, fiber. There is also bile, bacterial organisms, and salts.
In connection with the functions of the rectum, processes such as the breakdown of food that has not been digested in other parts of the digestive tract are observed there. And the formation of feces. In the large intestine, digestive juice is constantly secreted, containing the same set of enzymes as in the small intestine, but with a less pronounced potency. This is where the gases are collected.
The key function of the rectum is to remove waste from the life process. Or, in other words, removing feces from the body. This process is mainly regulated by the consciousness and will of a person.
Dysfunction of the rectum, as a rule, is the consequence of a sedentary lifestyle, poor nutrition, neuro-emotional overload, etc. Most often, such stressful situations lead to constipation. To disruption of intestinal function, affecting the process of defecation.
Circulatory processes
The blood supply to the rectum occurs thanks to the unpaired superior rectum and two paired rectums. A well-developed network of vessels of the sigmoid colon makes it possible to maintain a complete blood supply to the unpaired rectal artery, namely its marginal vessels, even due to high intersections of the paired rectal arteries and the sigmoid artery.
The middle paired arteries emerging from the branch sometimes develop differently, and sometimes are absent. And, nevertheless, in some situations they can play a key role in the process of blood supply.
The inferior arteries, originating from the internal pudendal artery, supply the external sphincter and skin. Plexus of veins are located in a wide variety of layers of the intestinal walls. Among them are:
- submucosal plexus - has a ring shape, consists of a submucosal membrane and venous trunks, and is also connected with the other two plexuses;
- subfascial plexus;
- subcutaneous plexus.
Finally
If we talk briefly about the function of the human rectum, we can summarize it as follows. This organ is responsible, first of all, for the storage site of feces and the reservoir for gas accumulation. This is also where undigested food is broken down and waste products are removed.
Rectum, located in the pelvic cavity, at its posterior wall, formed by the sacrum, coccyx and the posterior section of the pelvic floor muscles. It starts from the end of the pelvic part of the sigmoid colon at the level of the third sacral vertebra and ends in the perineal area with the anus. Its length is 14-18 cm. The diameter of the rectum varies from 4 cm (starting from the sigmoid colon) to 7.5 cm in the middle part (ampulla) and again decreases to a slit at the level of anus.
Consists of two parts: pelvic and perineal. The first is located above the pelvic diaphragm, in the pelvic cavity, and in turn is divided into a narrower supramullary section and a wide ampulla of the rectum, ampulla recti. The second part of the rectum lies under the pelvic diaphragm, in the perineum, and represents the anal canal, canalis analis.
The pelvic part of the rectum forms a bend in the sagittal plane, open anteriorly, corresponding to the concavity of the sacrum - the sacral bend, flexura sacralis; The upper part of the intestinal bend follows from front to back and down, the lower part - from back to front and down.
In the frontal plane, the pelvic part forms inconsistent bends; the upper part of the bend goes from left to top to bottom and to the right, the lower part goes in the opposite direction. The second bend in the sagittal plane, but already concave back, is located at the transition of the pelvic part to the perineal part; Having passed the pelvic diaphragm, the rectum sharply turns (almost at a right angle) back, forming a perineal bend, flexura perinealis. At this level, the rectum seems to go around the top of the coccyx. The length of the pelvic part ranges from 10 to 14 cm, the perineal part is about 4 cm.
At the level of the lower edge of the third sacral vertebra, the rectum begins to lose its serous cover: first from the posterior surface, then from the lateral and, finally, from the anterior. Thus, the upper, supramullary, section of the pelvic part of the rectum is located intraperitoneally, the upper part of the ampulla is surrounded by a serous membrane on three sides, and the lowest section of the ampulla lies retroperitoneal, since the peritoneum covers only a small area of the anterior wall here.
The line along which the peritoneum leaves the intestinal wall follows obliquely from above, from behind downward and forward. As the wall of the pelvic rectum loses its peritoneal covering, it is replaced by the visceral fascia of the pelvis, which forms the sheath of the rectum.
The perineal part of the rectum has the form of a longitudinal slit and opens in the recess of the intergluteal groove with the anus, anus, almost halfway between the coccyx and the root of the scrotum in men or the posterior commissure of the labia majora in women, at the level of the transverse line connecting both ischial tuberosities.
The structure of the rectal wall.
The serous membrane (peritoneum), tunica serosa, is part of the wall of the rectum only for a small extent. The extraperitoneal part of the pelvic rectum is surrounded by the visceral fascia of the pelvis; the fascia is not directly adjacent to the muscular layer of the intestinal wall. Between the visceral fascia and the muscle layer lies a layer of fatty tissue, there are nerves that supply the intestine with blood vessels and The lymph nodes. Anterior section The fascia of the rectum is a plate that separates the intestine from the organs lying in front: Bladder, prostate gland, etc. This plate is a derivative of fused serous layers of the deepest part of the peritoneal recess of the small pelvis; it goes from the bottom of the rectouterine recess (or rectovesical recess in men) to the tendon center of the perineal muscles and is called the peritoneal-perineal fascia, fascia peritoneoperinealis, or rectovesical septum, septum rectovesicale. Dorsally, the rectal fascia ends at midline posterior wall of the rectum.
The muscular layer, tunica muscularis, of the rectum consists of two layers: the outer longitudinal, stratum longitudinale, less thick, and the inner circular, stratum circulare, thicker. The longitudinal layer is a continuation of the muscle bands of the sigmoid colon, which here expand and cover the intestine in a continuous layer. On the anterior and posterior walls, the longitudinal muscle bundles are more developed. The longitudinal muscle layer of the lower part of the ampulla is woven into bundles coming from the anterior sacrococcygeal ligament - the rectococcygeal muscle, m. rectococcygeus. Part of the muscle fibers of the longitudinal layer is woven into the levator ani muscle, m. levator ani, and part reaches the skin of the anus.
In men, on the anterior surface of the lower part of the rectum, part of the longitudinal muscle bundles forms a small rectourethral muscle, m. rectouretralis. This muscle is attached to the tendon center of the perineum where the membranous part of the urethra passes through it. In addition, slightly higher in men there is a rectovesical muscle, which is a muscle bundle that connects the longitudinal muscle bundles of the bladder with the same bundles of the rectum.
The circular muscular layer of the rectum extends all the way to the anus; here it thickens, forming the internal sphincter of the anus, m. sphincter ani internus. Anterior to the anus, bundles of its muscles are woven into the sphincter of the membranous part of the urethra (in men) and into the muscles of the vagina (in women). Around the anus subcutaneous tissue The external anal sphincter is located, m. sphincter ani externus. This muscle belongs to the group of striated muscles of the perineum. Its outer, more superficial part covers medial section levator ani muscle; the deeper section is adjacent to the circular layer of the rectum, which forms the internal sphincter here. The levator ani muscle enters the space between the external and internal sphincters of the rectum. The anterior part of this muscle is the pubococcygeus muscle, m. pubococcygeus, covers the perineal part of the rectum in the form of a loop from behind.
The muscles of the circular layer of the rectum form thickenings at the location of the transverse folds of the mucous membrane (see below). The most pronounced thickening is located 6-7 cm above the anus. Here the transverse folds of the rectum, plicae transversales recti, are clearly distinguished; the middle of them is the most pronounced; a large number of circular muscle fibers lie in its thickness.
The mucous membrane, tunica mucosa, of the rectum is covered with epithelium, contains intestinal glands (crypts), glandulae intestinales (criptae), but is devoid of villi; in the submucosa, tela submucosa, there are single lymphatic follicles. Throughout the pelvic section of the rectum, the mucous membrane forms three, sometimes more, transverse folds, plicae transversales recti, covering half the circumference of the intestine. Of these three folds, the upper one is located at a level of up to 10 cm from the anus. In addition to transverse folds, the mucous membrane has a large number of unstable folds running in different directions. The mucous membrane of the lower part of the rectum (anal, anal, canal) forms up to 10 longitudinal folds - anal (anal) columns, columnae anales, the width and height of which increase downwards. The upper ends of the anal columns correspond to the rectal-anal line, linea anorectalis. Distal to the anal columns is a slightly swollen annular area with a smooth surface of the mucous membrane - the intermediate zone. The protruding intermediate zone, as it were, closes the depressions between the pillars from below, turning them into pockets - the anal (anal) sinuses, sinus anales. The anal glands lie at the bottom of these sinuses. The transverse folds of the intermediate zone, closing the sinuses from below, as if connecting the anal columns, are called anal valves, valvulae anales. The combination of the anal valves forms a ridge of the mucous membrane - the anal (anal) ridge, pecten analis. The submucosa of the anal column zone and the intermediate zone is loose tissue in which the rectal venous plexus lies. In the intermediate zone, this plexus forms a continuous ring; in the submucosa of the anal column area, except venous plexuses, lie bundles of longitudinal muscle points.
Approximately the same for women and men. But since the intestines are located somewhere in the same area as the genitals, they have their own characteristics and differences.
This article discusses the structure of the organ in men and women, its functions and possible diseases.
More about the rectum
This organ descends to the pelvis, forming curves. One of them is convex forward, and the other protrudes backward, repeating the curve of the sacrum.
The length of the intestine is from 10 to 15 cm. The organ consists of muscle tissue, mucous membrane and submucosal part, is located in a connective tissue membrane - in the male body it also covers the prostate gland, and in the female body it envelops the cervix.
The mucous membrane is covered epithelial tissue, which contains a large number of Lieberkühn crypts (glands).
These glands, in turn, consist of cells that produce mucus, which explains why mucus is secreted from the intestines in various diseases.
Just above the anus are the rectal columns of Morgagni, formed by a fold of mucous tissue. They resemble columns, their number varies from 6 to 14.
Between the columns there are niches called pockets. Quite often they retain fecal residues, which can cause inflammation.
Intestinal diseases and disorders motor function irritate the intestinal mucosa, which is why papillae may appear on it, the size of which depends on how severely the mucosa is irritated. Sometimes the irritation is mistaken for a polyp.
Blood enters the rectum from several hemorrhoidal arteries - from the lower, middle and upper. The first two are paired, but the top one is not.
Blood moves through the veins through the hollow and portal veins; in the lower part of the rectum there are many large venous plexuses.
In women, the structure of the intestine is different from the male body. This is influenced by the characteristics of the female reproductive system.
In women, the rectum is adjacent to the vagina in front - between the organs, of course, there is a separating layer, but it is very thin.
If inflammation occurs in one of these organs, it is likely that it will spread to the neighboring organ.
Because of this internal structure Women quite often develop fistulas that affect both the intestines and the organs of the reproductive system.
This disease is a consequence of problematic childbirth or any trauma.
The rectum is the last part of the intestine that ends with the sphincter. Surprisingly, the anus in men and women has a different structure.
The sphincter or anus is a depression that goes into the rectum. Depending on the structure of the body, it may be located quite deep or not very deep.
In men, for example, the sphincter may be funnel-shaped, while in women it is flatter and protrudes slightly forward.
In women, such a structure of the sphincter may be due to the fact that its muscles are stretched too much.
How does defecation occur?
The rectum is part of the large intestine, which also includes the sigmoid, ascending, descending and transverse. You need to understand how everything works in general in order to look at the rectum individually.
In men and women, approximately 4 liters of digested food (chyme), which comes from the stomach, enters the large intestine per day from the small intestine.
The large intestine mixes this pulp, resulting in the formation of feces in a person.
This happens due to the fact that the organ performs wave-like contractions, which causes the chyme to thicken. Ultimately, out of 4 liters of digested food, about 200 g of feces remain.
Usually feces consist not only of chyme residues, but also of mucus, cholesterol, bacteria, cholic acid, etc.
The organ absorbs food, and all the toxic and harmful substances of the chyme penetrate into the blood, which enters the liver. In the liver, “harmful” blood is retained and then released along with bile.
After all this, bowel movement occurs, which is ensured by the actions of certain intestinal mechanisms.
With the help of peristalsis, feces enter the sigmoid colon, where they accumulate and are temporarily retained.
Stopping further movement of feces in this part of the intestine occurs due to contractions of the muscles that are located in the intestine.
Not only the intestinal muscle layer, but also the abdominal muscles help push out the contents of the intestines.
Additional help from another muscle group helps push feces into the anal canal for constipation and various cramps. After defecation, the organ is free for some time and does not fill.
This part of the intestine has a strong influence on the functioning of the stomach. If any problems arise, this affects the digestive process, the secretion of saliva and bile.
The brain also affects defecation: if a person is worried or tired, it delays bowel movements.
Possible diseases
Since the structure of the intestine in the female and male body is different, there are also quite a lot of diseases that can be found in this organ.
One of the most common diseases of the rectum is proctitis. Simply put, inflammation of the mucous membrane.
This disease may be caused excessive consumption spicy foods and spices, as well as constipation, during which there is stagnation of feces.
Feces can remain in the “pockets” between the columns of Morgagni, gradually poisoning the body, which can also lead to congestive proctitis.
Inflammation of the rectal mucosa can begin after unsuccessful laser therapy.
For example, if a person has a tumor in the pelvic region, then as a result radiation therapy Proctitis may well develop.
Inflammation of the mucous membrane can also occur from hypothermia, hemorrhoids, cystitis, prostatitis, etc.
Proctitis can be chronic or acute. The first type of pathology occurs almost unnoticed, accompanied by slight itching and burning in the anal canal.
Acute proctitis occurs suddenly and is characterized by high temperature, heaviness in the intestines, chills, burning in the intestines.
This type of proctitis occurs infrequently, with timely treatment maybe enough fast recovery sick.
But the prognosis for chronic proctitis is more disappointing, because with this type of disease exacerbations periodically occur.
Rectal prolapse is a pathology in which the wall of the organ falls out through the sphincter.
This is most often observed in women who have undergone difficult childbirth, since after it the woman’s anus muscles can be significantly stretched and injured, and ruptures are possible.
However, bowel prolapse also occurs in men. Typically, this can occur due to changes in the muscles of the anus during the aging process, from bowel surgery. Constipation can lead to pathology if a person regularly strains for a long time in the toilet.
Usually the disease begins with constipation and other difficulties during bowel movements in childhood, but the first signs of the disease in adulthood are also possible.
With this pathology, a person begins to experience itching in the anus, fecal incontinence, and blood and mucus are released.
Diagnosis of rectal prolapse is made by palpation. The doctor may also ask the patient to push - then part of the intestine becomes visible. If polyps are suspected, a colonoscopy may be performed.
For adults in such cases it is only indicated surgical intervention. During the operation, the patient's intestinal ligaments are strengthened.
If a person also complains of incontinence, then the muscles of the anus are additionally strengthened.
Although the operation is rather large, it can be performed by almost anyone – even the elderly.
Quite often, intestinal prolapse occurs along with uterine prolapse in women. If a woman is elderly or does not intend to have children, then the uterus is removed.
If bowel prolapse occurs in young man without other health problems, they may prescribe conservative treatment, which includes special physical exercise, strengthening the muscles of the anus, and a diet rich in essential vitamins.
The rectum performs the function of defecation, the final function of the intestines. It is located in the posterior part of the small pelvis and ends in the perineum.
In men, the prostate gland, the posterior surface of the bladder, the seminal vesicles and the ampoules of the vas deferens are located in front of the rectum. In women, the uterus and posterior arch vagina. At the back, the rectum lies next to the coccyx and sacrum.
The upper border of the intestine is located at the level of the upper edge of the third sacral vertebra.
The rectum is the final section. When it is not filled, longitudinal folds form in the mucous membrane. They disappear when the intestine is distended.
The length of the rectum does not exceed 15 cm. top part surrounded by three transverse folds. The rectum ends in the anorectal region.
The rectum forms two bends. The sacral flexure is curved towards the spine, and the perineal flexure - towards the side abdominal wall. There are two sections of the rectum - pelvic and perineal. The border between them is the place of attachment of the levator ani muscle. The pelvic section, located in the pelvic cavity, consists of the supramullary and ampullary sections. The ampullary section has the shape of an ampulla with an expansion at the level of the sacrum. The perineal section of the rectum is also called the anal canal. It opens outward through the anus.
Muscularis
The muscular layer of the rectum is formed by outer longitudinal and inner circular layers. Transverse folds are formed by the circular muscles. The longitudinal layer contains fibers of the levator ani muscles. In the anal canal, 8-10 longitudinal folds are formed, the basis of which is smooth muscle and connective tissue.
The outlet of the rectum is ring-shaped by the muscular external sphincter of the anus (voluntary sphincter). At a distance of 3-4 cm from the anus, the thickening of the circular muscles forms another sphincter (involuntary). At a distance of 10 cm from the anus, the circular muscles form another involuntary sphincter.
Blood supply to the rectum
The blood supply to the rectum is provided by the superior and inferior rectal arteries. The superior rectal artery is a continuation of the inferior mesenteric artery, and the inferior rectal arteries are branches of the internal cava artery.
Thanks to this blood supply, the rectum is not involved in the pathological process during the development of ischemic colitis.
The outflow of blood occurs through the corresponding veins. These veins form plexuses in the wall of the rectum. In the submucosa of the anal canal, at the level of the anal valves, there is cavernous vascular tissue. Recent studies have convincingly proven that it is she who forms hemorrhoids.
The mucous membrane contains single lymphoid nodules and sebaceous glands. At the border of the intestinal mucosa and skin there are sweat glands and hair follicles. The rectal mucosa has good absorption capacity. This quality is used to administer nutritional fluids and medicinal substances through the rectum through suppositories, enemas and irrigations.
Innervation
From the point of view of its functions, the most important part of the smooth muscles of the rectum and anal canal is the internal sphincter. It provides residual pressure in the rectal lumen. Physical activity This sphincter is inhibited and stimulated by both the sympathetic and parasympathetic nervous systems.
Functions of the rectum
The rectum has two functions:
- anal continence (accumulation of feces)
- defecation (evacuation of feces).
Anal holding
Violation of the function of holding the intestinal contents of the rectum brings the greatest inconvenience to a person and creates problems of both a social and medical nature.
In its natural position, the internal anal sphincter is always contracted.
It relaxes only when the rectum is stretched. Immediately after stretching the rectum and relaxing the internal sphincter, the rectosphincteric relaxation reflex occurs.
Retention of intestinal contents is normal condition and is regulated unconsciously. However, volitional influence on this function is also possible. Retention depends on the interaction of many factors.
Chief among them is the consistency of feces in direct and colon. No less important is the coordination of the activity of smooth and transverse orbicularis muscles in the area of the anal canal. Of course, the anatomical integrity of all components of this process is necessary.
The smooth muscles of the anal canal, rectum and internal anal sphincter respond to local stimuli and to reflexes transmitted by the autonomic nervous system.
Transverse muscles voluntary sphincter controlled by centers of the spinal cord and brain. This is carried out by centrifugal and centripetal nerve fibers.
So what has the greatest impact on grip function? It was assumed that this role is shared between the internal and external anal sphincters. However, cutting the internal sphincter only affects gas incontinence. And dissection of the external sphincter also leads to gas incontinence and difficulty in holding large amounts of liquid feces.
It turned out that the holding function is determined mainly by the state of the puborectalis muscle, which maintains the required anorectal angle. When this muscle is damaged, severe fecal incontinence occurs.
Defecation
Defecation is difficult process, adjustable reflexively. It is divided into two interrelated phases:
- afferent and
- efferent.
In the afferent phase, an urge is formed, and in the efferent phase, feces are released.
The urge to defecate occurs when feces enter the rectum from the sigmoid colon. At the same time, they put pressure on the puborectalis muscle, in which numerous receptors are located. Afferent excitations are transmitted to the cerebral cortex. Here it influences the formation of the urge to defecate; it can be both inhibitory and intensifying the process.
When the urge occurs, feces continue to be retained in the rectum due to the internal and external sphincters. Emptying occurs reflexively and is controlled by an impulse from the central nervous system. If, when the urge occurs, the situation is unfavorable for defecation, then voluntary contraction of the external sphincter causes the pelvic floor to rise, the anorectal angle increases and the feces are forced to rise upward.
Regular inhibition of the process of defecation when the urge occurs (volitional inhibition) can lead to disruption of the regulatory functions of the body, which in turn will lead to constipation.
The influence of the central nervous system on this process has not been fully studied. Thus, uncontrollable fecal incontinence may occur as an idiopathic phenomenon, but can occur with multiple sclerosis and other diseases of the nervous system.
In older people, constipation may occur due to weakening of the pelvic floor muscles and diaphragm.
Strong emotional stress can cause involuntary relaxation of the internal and external sphincters and lead to a violation of the act of defecation, known as “bear disease”.
An increased frequency of urges can also be caused by the effects of toxic substances on intestinal receptors. For various poisonings, this contributes to accelerated withdrawal harmful substances from the body.
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