What is included in bile? Bile: features, chemical properties, composition and biological value

Bile produces special cells - hepatocytes, of which the human liver almost entirely consists. Hepatic structures include, which stores bile, starts the processes of its circulation, but does not secrete it. Bile enters the biliary tract, then penetrates the digestive tract, after which it takes an active part during the digestive act. The complex composition of bile, as well as numerous processes of bile excretion and bile production, characterize the high biological significance of the secretion. Even with a slight disturbance, a person experiences a decrease in the functionality of the liver structures and parts of the epigastric organs. To understand the importance of bile, you should know which organ produces bile and what the secreted fluid is responsible for?

Anatomical location of the liver

Features of secretion

Bile is a yellow, brownish or green liquid with a pronounced bitter taste and characteristic odor. It is secreted by liver cells and accumulates in the cavity of the gallbladder. The secretion process is carried out by hepatocytes, which are liver cells. The liver structures where bile is formed are completely dependent on this secretion. The volume of bile collects in the bile ducts and enters the gallbladder and small intestine, where it completes the digestive processes. The gallbladder acts as a biological fluid reservoir, from which a certain volume of bile is distributed throughout the lumens of the small intestine when a bolus of food previously broken down in the stomach penetrates there. The human body produces up to 1 liter of bile per day, regardless of the fluid consumed. Water, in this case, acts as a transport that delivers all the components of the acid to the cavity of the gallbladder.

The bile in the gallbladder is densely concentrated, dehydrated, has a moderate viscous consistency, and the color of the liquid varies from dark green to brown. A golden-yellow hue may appear due to the abundance of water consumed per day. Bile does not reach the intestines during an empty stomach. The secretion is delivered to the cavity of the bladder, where, when stored, it is concentrated and adaptively changes its chemical components. The ability to exhibit adaptive properties at the time of supply for the digestive act and at the same time deposition classifies bile into two main types: cystic and hepatic.

Important! From the Greek language, bile (in Russian transcription “chole”) means suppression, oppression. Since ancient times, bile has been associated with blood. If healers compared blood to the soul, then bile was considered the carrier of a person’s character. If there was an excess of secretion of a light shade, a person was considered harsh, impetuous, unbalanced. Dark bile testified to the severity of the person’s character. Today, psychology clearly defines 4 human psychotypes, and in each of them the root “chol” is preserved - bile, despite the fact that there is no explicable connection between bile, its color, other parameters and a person’s disposition.

Functional Features

So, what is bile for and what functions does it perform? Bile has a special biological value in the human body. This glandular secretion is assigned by nature many different functions that completely regulate the following processes in the body:

neutralizing the effect of pepsin, a component of gastric juice;
participation in the production of micelles;
activation of regeneration of hormonal processes in the intestines;
participation in the emulsification of fatty components and the production of mucus;
maintaining motility of the digestive organs;
easy digestion of protein.

Liver and bile ducts

All enzymatic functions of bile ensure the normal passage of food through the food passages, break down complex fats, proteins, carbohydrates, and ensure the maintenance of normal microflora in the liver and gall bladder. Other important functions of bile in the body include the following:

providing bile to the cavity of the small intestine;
ensuring normal metabolic processes;
production of synovial fluid (shock-absorbing secretion of interarticular structures).

With minor changes in the composition of bile, many systems fail, provoking the formation of stones in the ducts of the gallbladder and in its cavity, improper formation of feces, reflux of bile secretions and other pathologies.

Important! Changes in the composition of bile can be influenced by the patient's obesity, complicated endocrinological history, sedentary lifestyle, and severe liver diseases. Functional disorders of the gallbladder provoke the persistent development of its hyperfunction or insufficiency.

Components

Bile refers not only to secretion, but also performs many excretory functions. Its composition includes multiple substances of endogenous or exogenous nature, protein compounds, acids and amino acids, and a rich vitamin complex. Bile consists of three main fractions, two of which are the result of the activity of hepatocytes, and the third is created by the epithelial structures of the bile ducts. The important components of bile include the following components:

water (up to 80%);
bile salts (about 8-10%);
mucus and pigments (3.5%);
fatty acids (up to 1-2%);
inorganic salts (about 0.6%);
cholesterol (up to 0.3-.0.4%).

Considering the two main types of bile - hepatic and bladder, the constituent components of both types are different. Thus, in the bladder secretion, various salts are significantly higher, and in the liver secretion there are more other components: sodium ions, bicarbonates, bilirubin, lecithin and potassium.

Important! The composition of bile secretion includes a large number of different bile acids, because it is bile that emulsifies fats. It is the production of bile acids that will allow the destruction of cholesterol and its compounds. To carry out the process of cholesterol catabolism, 17 acids of various types are required. At the slightest fermentation failure, a change in the function of bile occurs at the genetic level.

Clinical relevance

The absence of secretion makes the fats supplied with food indigestible, so they are excreted unchanged, undigested, along with feces. Pathology in the absence or severe deficiency of bile secretion is called steatorrhea. The disease often leads to a deficiency of nutrients, vitamins, and important fatty acids. The food itself, passing through the lumens of the small intestine, where fat absorption occurs, without bile, completely changes the microflora of the intestinal tract. Given the presence of cholesterol in bile, which often combines with calcium, bilirubin forms gallstones. Treatment of calculi (organic stones) occurs only surgically, which involves removing the gallbladder. If there is insufficient secretion, they resort to prescribing drugs that promote the breakdown of fats and restoration of intestinal microflora.

Gallbladder

Important! What color is bile? The color of bile is often compared to the hue of freshly cut grass, but when mixed with the components of the stomach, it produces a green-yellow or deep yellow hue.

Major diseases

Often, diseases associated with bile formation and bile secretion are formed based on the volume of secretion produced, its release into the small intestine, as well as the quality of the release. Usually, it is the insufficiency of bile formation and the return of secretions into the stomach that are the main causes of diseases of the gastrointestinal tract. The main ones include:

Stone formation. Gallstones are formed when the composition of the secretion is unbalanced (otherwise known as lithogenic bile), when bile enzymes are severely deficient. The lithogenic properties of bile fluid manifest themselves as a result of the lack of a diet, when eating plant and animal fats in large quantities. Other reasons are endocrinological disorders, especially against the background of neurological disorders, disorders of fat metabolism in the body with a tendency to increase body weight, liver damage of any origin, and hypodynamic disorders.
. The disease occurs in the complete absence of bile or in bile insufficiency. Against the background of pathology, the emulsification of fats stops, they are formed unchanged along with feces and are excreted in the form of feces. Steatorrhea is characterized by a lack of fatty acids and vitamins in the body, when the structures of the lower intestines are simply not adapted to undigested fats in the food bolus.
Reflux gastritis and GERD. The pathology consists of the backflow of bile into the stomach or esophagus in a noticeable volume. With duodenogastric and duodenogastroesophageal refluxes, bile enters the mucous membranes, causing their necrotization and necrobiotic changes. Damage to the upper layer of the epithelium leads to the formation of reflux gastritis. Gastroesophageal reflux disease (abbr. GERD) is formed due to damage to the esophageal mucosa against the background of an acidic pH in the esophagus. Bile penetrating into the esophagus provokes the formation of various variations of GERD.

When bile is formed, almost all organs close to the liver and gallbladder are involved. This proximity is due to the severity of pathologies with insufficiency or absolute absence of bile.

Diagnosis of pathology

Considering the polyetiology of diseases due to disturbances in the processes of formation and release of bile fluid in the required volumes, comprehensive diagnostics are carried out, consultations with other specialists in the field in case of a burdened clinical history of the patient. In addition to a physical examination, studying the patient’s medical history and his complaints, palpation of the peritoneum and epigastrium, a number of laboratory and instrumental studies are carried out:

esophagogastroduodenoscopy (to identify bile);
ultrasonography (abdominal) (determining the diameter of the bile ducts at the time of eating);
ultrasound of the liver, gall bladder and abdominal organs;
dynamic echography;
X-ray gastroscopy;
gastrography with contrast;
hydrogen test;
endoscopic studies.

Endoscopic examinations allow the collection of stomach tissue and cavity contents for detailed study. Using the endoscopic method, doctors determine the degree of narrowing of the small intestine, the rhythm of peristalsis, possible congestion, atrophic metaplasia of the epithelium, and a decrease in the propulsive intensity of the stomach.

Composition and properties of bile, functions of bile, types of bile (hepatic, bladder)

The gallbladder, vesica fellea, is a reservoir in which bile accumulates. It is located in the fossa of the gallbladder on the visceral surface of the liver and is pear-shaped.

Gallbladder has a blind extended end - the bottom of the gallbladder, fundus vesicae felleae, which emerges from under the lower edge of the liver at the level of the junction of the cartilages of the VIII and IX right ribs. The narrower end of the bladder, directed towards the gate of the liver, is called the neck of the gallbladder, collum vesicae felleae. Between the bottom and the neck is the body of the gallbladder, corpus vesicae felleae. The neck of the bladder continues into the cystic duct, ductus cysticus, which merges with the common hepatic duct. The volume of the gallbladder ranges from 30 to 50 cm3, its length is 8-12 cm, and its width is 4-5 cm.

The structure of the gallbladder wall resembles the intestinal wall. The free surface of the gallbladder is covered with peritoneum, passing onto it from the surface of the liver, and forms a serous membrane, tunica serosa. In those places where the serous membrane is absent, the outer membrane of the gallbladder is represented by adventitia. The muscular coat, tunica muscularis, consists of smooth muscle cells. The mucous membrane, tunica mucosa, forms folds, and in the neck of the bladder and in the cystic duct it forms a spiral fold, plica spiralis.

The common bile duct, ductus choledochus, goes down first behind the upper part of the duodenum, and then between its descending part and the head of the pancreas, pierces the medial wall of the descending part of the duodenum and opens at the apex of the major duodenal papilla, having previously connected with the pancreatic duct. After the merging of these ducts, an expansion is formed - the hepatopancreatic ampulla (ampulla of Vater), ampulla hepatopancreatica, which has at its mouth the sphincter of the hepatopancreatic ampulla, or the sphincter of the ampulla (sphincter of Oddi), m. sphincter ampullae hepatopancredticae, seu sphincter ampullae. Before merging with the pancreatic duct, the common bile duct in its wall has a sphincter of the common bile duct, i.e. sphincter ductus choledochi, which blocks the flow of bile from the liver and gallbladder into the lumen of the duodenum (into the hepatic-pancreatic ampulla).

Bile produced by the liver accumulates in the gallbladder, entering there through the cystic duct from the common hepatic duct. The exit of bile into the duodenum is closed at this time due to contraction of the sphincter of the common bile duct. Bile enters the duodenum from the liver and gall bladder as needed (when food gruel passes into the intestine).

Composition of bile

Bile consists of 98% water and 2% dry residue, which includes organic substances: bile salts, bile pigments - bilirubin and biliverdin, cholesterol, fatty acids, lecithin, mucin, urea, uric acid, vitamins A, B, C; a small amount of enzymes: amylase, phosphatase, protease, catalase, oxidase, as well as amino acids and glucocorticoids; inorganic substances: Na+, K+, Ca2+, Fe++, C1-, HCO3-, SO4-, P04-. In the gallbladder, the concentration of all these substances is 5-6 times higher than in the liver bile.

Properties of bile varied and they all play an important role in the digestive process:

Emulsification of fats, that is, their breakdown into the smallest components. Thanks to this property of bile, a specific enzyme in the human body, lipase, begins to dissolve lipids in the body especially effectively.

[The salts that make up bile break down fats so finely that these particles can enter the circulatory system from the small intestine.]

The ability to dissolve lipid hydrolysis products, thereby improving their absorption and transformation into final metabolic products.

[Bile production helps improve the activity of intestinal enzymes, as well as substances secreted by the pancreas. In particular, the activity of lipase, the main enzyme that breaks down fats, increases.]

Regulating, since the fluid is responsible not only for the process of formation of bile and its secretion, but also for motility. Motility is the ability of the intestines to push food through. In addition, bile is responsible for the secretory function of the small intestine, that is, for the ability to produce digestive juices.

Inactivation of pepsin and neutralization of the acidic components of gastric contents that enter the cavity of the duodenum, thereby performing the protective function of the intestine against the development of erosion and ulceration.

Bacteriostatic properties, due to which pathogens are inhibited and spread in the digestive system.

Functions of bile.

replaces gastric digestion with intestinal digestion by limiting the action of pepsin and creating the most favorable conditions for the activity of pancreatic juice enzymes, especially lipase;

due to the presence of bile acids, it emulsifies fats and, by reducing the surface tension of fat droplets, helps to increase its contact with lipolytic enzymes; in addition, it ensures better absorption in the intestines of water-insoluble higher fatty acids, cholesterol, vitamins D, E, K and carotene, as well as amino acids;

stimulates intestinal motor activity, including the activity of intestinal villi, resulting in an increased rate of absorption of substances in the intestine;

is one of the stimulants of pancreatic secretion, gastric mucus, and most importantly, the liver function responsible for bile formation;

due to the content of proteolytic, amylolytic and glycolytic enzymes, it participates in the processes of intestinal digestion;

has a bacteriostatic effect on the intestinal flora, preventing the development of putrefactive processes.

In addition to the listed functions, bile plays an active role in metabolism- carbohydrate, fat, vitamin, pigment, porphyrin, especially in the metabolism of protein and the phosphorus contained in it, as well as in regulation of water and electrolyte metabolism.

Types of bile.

Liver bile is golden yellow in color, bladder bile is dark brown; pH of hepatic bile - 7.3-8.0, relative density - 1.008-1.015; The pH of gallbladder bile is 6.0-7.0 due to the absorption of bicarbonates, and the relative density is 1.026-1.048.

Bile, a secretion product of liver cells, is a golden-yellow liquid with an alkaline reaction (pH 7.3-8.0) and a density of 1.008-1.015.

In humans, bile has the following composition: water 97.5%, solids 2.5%. The main components of the dry residue are bile acids, pigments and cholesterol. Bile acids are classified as specific metabolic products of the liver. In humans, cholic acid is found predominantly in bile. Among the bile pigments, bilirubin and biliverdin are distinguished, which give bile its characteristic color. Human bile contains mainly bilirubin. Bile pigments are formed from hemoglobin, which is released after the destruction of red blood cells. In addition, bile contains mucin, fatty acids, inorganic salts, enzymes and vitamins.

A healthy person secretes 0.5·10 -3 -1.2·10 -3 m 3 (500-1200 ml) of bile per day. Bile is secreted continuously and enters the duodenum during digestion. Outside of digestion, bile enters the gallbladder, therefore a distinction is made between bladder and hepatic bile. Cystic bile is dark, has a viscous and viscous consistency, its density is 1.026-1.048, pH 6.8. The differences between gallbladder bile and liver bile are due to the fact that the mucous membrane of the bile ducts and bladder produces mucin and has the ability to absorb water.

Bile performs diverse functions that are closely related to the activity of the gastrointestinal tract. Bile is classified as digestive juices. However, it also performs an excretory function, since it removes various exo- and endogenous substances from the blood. This distinguishes bile from other digestive juices.

Bile increases the activity of pancreatic juice enzymes, primarily lipase. The influence of bile on the digestion of proteins, fats, and carbohydrates is carried out not only through the activation of enzymes of pancreatic and intestinal juices, but also as a result of the direct participation of its own enzymes (amylase, proteases) in this process. Bile acids play a large role in fat assimilation. They emulsify neutral fats, breaking them into a huge number of tiny droplets, and, thereby increasing the surface of contact between fat and enzymes, facilitate the breakdown of fats, increasing the activity of pancreatic and intestinal lipase. Bile is necessary for the absorption of fatty acids and therefore fat-soluble vitamins A, D, E and K.

Bile enhances the secretion of pancreatic juices, increases tone and stimulates intestinal motility (duodenum and colon). Bile is involved in parietal digestion. It has a bacteriostatic effect on the intestinal flora, preventing the development of putrefactive processes.

Methods for studying the bile-forming and biliary functions of the liver

In the biliary activity of the liver, one should distinguish between bile formation, i.e., the production of bile by liver cells, and bile secretion - the exit, evacuation of bile into the intestine. In experimental physiology, there are two main methods for studying these two aspects of the biliary activity of the liver.

To study the bile-forming function of the liver, the common bile duct is ligated, thereby preventing the flow of bile into the intestine. At the same time, a fistula is placed on the gallbladder. With the help of this operation, all the bile that flows and is continuously produced by the liver cells is collected from dogs.

To study the bile-secreting function of the liver and the role of bile in the digestive process, I. P. Pavlov proposed the following operation. In dogs under anesthesia, a small flap is cut from the wall of the duodenum, in the center of which is the common bile duct. This piece of intestine is brought to the surface and sewn into the skin wound of the abdominal wall. The integrity of the intestine is restored by suturing. During this operation, the innervation of the sphincter of the common bile duct is preserved.

When observing operated animals, it was found that the secretion of bile occurs simultaneously with the secretion of pancreatic juice. Bile is secreted almost immediately after eating, its secretion reaches a maximum by the 3rd hour and then decreases quite quickly. It was also found that fatty foods have a pronounced choleretic effect, and to a lesser extent this is characteristic of carbohydrates. Meat occupies a middle position among foods that can increase bile secretion. Consequently, the intensity of bile flow into the duodenum depends on the nature of the food taken.

To study the secretion of bile in humans, the X-ray method and duodenal intubation are used. During an x-ray examination, substances are introduced that do not transmit x-rays and are removed from the body with bile. Using this method, it is possible to establish the appearance of the first portions of bile in the ducts, gallbladder, and the moment of release of cystic and hepatic bile into the intestine. With duodenal intubation, fractions of hepatic and cystic bile are obtained.

Regulation of bile-forming and bile-excretory functions of the liver

Bile formation is a complex process that consists of three interrelated components. The first component of bile formation is represented by filtration processes. Due to filtration from the blood through capillary membranes, some substances enter the bile - water, glucose, sodium, calcium, chlorine ions. The second component of bile formation is the process of active secretion of bile acids by liver cells. The third component of bile formation is associated with the reabsorption of water and a number of other substances from the bile capillaries, ducts and gallbladder.

The bile-forming function of the liver is influenced by various factors. Stimulators of bile secretion are bile components found in the blood, hydrochloric and other acids, under the influence of which secretin is formed in the duodenum. This hormone not only promotes the formation of pancreatic juice, but also humorally, acting on liver cells, stimulates their production of bile.

The nervous system takes an active part in the regulation of the bile-forming function of the liver. It has been established that the vagus and right phrenic nerves, when excited, increase the production of bile by liver cells, while the sympathetic nerves inhibit it. The formation of bile is also influenced by reflex effects coming from the interoreceptors of the stomach, small and large intestines and other internal organs. The influence of the cerebral cortex on the production of bile by liver cells has been proven.

It has been established that hormones of some endocrine glands regulate bile formation. In particular, the pituitary hormones adrenocorticotropin and vasopressin, as well as insulin - the hormone of the islet apparatus of the pancreas - stimulate bile formation, and the thyroid hormone - thyroxine - inhibits it.

As already indicated, the formation of bile occurs continuously, regardless of whether food is in the digestive canal or not. Outside of the digestion process, bile enters the gallbladder.

A number of factors contribute to the flow of bile into the duodenum. The secretion of bile increases during the act of eating, which has a significant reflex effect on all secretory processes carried out in the gastrointestinal tract.

A study of the influence of the quantity and quality of food taken on the secretion of bile showed that milk, meat, and bread have a choleretic effect. In fats this effect is more pronounced than in proteins and carbohydrates. It was found that the duration of bile secretion for meat is on average 7 hours, for bread - 10 hours, for milk - approximately 9 hours. Bile is secreted in larger quantities for meat and milk, and in smaller quantities for bread. The maximum secretion for meat is observed at the 2nd hour, for bread and milk - at the 3rd hour after eating. It was also found that the greatest amount of bile is released with a mixed diet.

Mechanisms of gallbladder emptying

The flow of bile from the gallbladder into the duodenum is ensured by nervous and humoral mechanisms. The central nervous system mediates its influence on the muscles of the gallbladder, its sphincter and the sphincter of Oddi through the vagus and sympathetic nerves. Under the influence of the vagus nerves, the muscles of the gallbladder contract and at the same time the sphincters relax, which leads to the flow of bile into the duodenum. Under the influence of sympathetic nerves, relaxation of the gallbladder muscles, increased tone of the sphincters and their closure are observed. Emptying the gallbladder is carried out on the basis of conditioned and unconditioned reflexes. Conditioned reflex emptying of the gallbladder occurs at the sight and smell of food, talking about familiar and tasty food in the presence of appetite.

Unconditioned reflex emptying of the gallbladder is associated with the entry of food into the oral cavity, stomach, and intestines. Excitation of the receptors of the mucous membrane of these parts of the gastrointestinal tract is transmitted to the central nervous system, and from there along the fibers of the vagus nerve it enters the muscles of the gallbladder, its sphincter and the sphincter of the common bile duct. Bile enters the duodenum through open sphincters.

The influence of the nervous system is joined by the action of hormones formed in the gastrointestinal tract - cholecystokinin (or pancreozymin - HKKZ), urocholecystokinin, antiurocholecystokinin, gastrin. Cholecystokinin causes contraction of the gallbladder, relaxation of the sphincter of Oddi muscles and the terminal section of the common bile duct, i.e., it facilitates the flow of bile into the duodenum. Urocholecystokinin and, to a lesser extent, gastrin have a similar effect. Antiurocholecystokinin is formed in the mucous membrane of the gallbladder and cystic duct and is an antagonist of cholecystokinin and urocholecystokinin.

The sphincter of the gallbladder closes after it is emptied, but the sphincter of the common bile duct remains open throughout digestion, so bile continues to flow freely into the duodenum. As soon as the last portion of food leaves the duodenum, the sphincter of the common bile duct closes. At this time, the sphincter of the gallbladder opens and bile begins to accumulate in it again.

Bile is a complex liquid with an alkaline reaction. It contains a dry residue - about 3% and water - 97%. Two groups of substances are found in the dry residue:

got here by filtering from blood sodium, potassium, bicarbonate ions (HCO 3 ¯), creatinine, cholesterol (CS), phosphatidylcholine (PC),
actively secreted hepatocytes bilirubin and bile acids.

Normally between the main components of bile Bile acids: Phosphatidylcholine: Cholesterol the ratio is maintained equal 65: 12: 5 .

About 10 ml of bile per kg of body weight is produced per day, so in an adult this is 500-700 ml. Bile formation occurs continuously, although the intensity fluctuates sharply throughout the day.

The role of bile

1. Along with pancreatic juice neutralization acidic chyme coming from the stomach. In this case, HCO3 ions interact with HCl, carbon dioxide is released and the chyme is loosened, which facilitates digestion.

2. Provides fat digestion:

emulsification for subsequent action by lipase, a combination of [bile acids + fatty acids + monoacylglycerols] is required,
reduces surface tension, which prevents fat droplets from draining,
education micelles, capable of being absorbed.

3. Thanks to paragraphs 1 and 2, it provides suctionfat-soluble vitamins (vitamin A, vitamin D, vitamin K, vitamin E).

4. Strengthens peristalsis intestines.

5. Excretion excess cholesterol, bile pigments, creatinine, metals Zn, Cu, Hg, drugs. For cholesterol, bile is the only route of excretion; 1-2 g/day can be excreted with it.

Formation of bile (choleresis) goes on continuously, not stopping even during fasting.Gain choleresis occurs under the influence n.vagus and when eating meat and fatty foods. Decline– under the influence of the sympathetic nervous system and increased hydrostatic pressure in the bile ducts.

Biliary excretion ( cholekinesis) is ensured by low pressure in the duodenum, intensified under the influence n.vagus and is weakened by the sympathetic nervous system. Gallbladder contraction is stimulated bombesin, secretin, insulin And cholecystokinin-pancreozymin. Relaxation is caused glucagon And calcitonin.

The formation of bile acids occurs in the endoplasmic reticulum with the participation of cytochrome P 450, oxygen, NADPH and ascorbic acid. 75% of cholesterol produced in the liver is involved in the synthesis of bile acids.

Reactions of bile acid synthesis using the example of cholic acid

Synthesized in the liver primary bile acids:

cholic (3α, 7β, 12α, hydroxylated at C 3, C 7, C 12),
chenodeoxycholic(3α, 7α, hydroxylated at C 3, C 7).

Then they form paired bile acids– conjugates with glycine(glyco derivatives) and with taurine(tauro derivatives), in a ratio of 3:1, respectively.

Structure of bile acids

In the intestine, under the influence of microflora, these bile acids lose the OH group at C 7 and turn into secondary bile acids:

cholic to deoxycholic (3α, 12α, hydroxylated at C 3 and C 12),
chenodeoxycholic to lithocholic (3α, hydroxylated only at C 3) and 7-ketolithocholic(7α-OH group is converted to keto group) acid.

Also distinguished tertiary bile acids. These include

formed from lithocholic acid (3α) – sulfolitocholic(sulfonation at C 3),
formed from 7-ketolithocholic acid (3α, 7-keto) by reducing the 7-keto group to an OH group – ursodeoxycholic(3α, 7β).

Ursodeoxycholic acid is an active component of the drug "Ursosan" and is used in the treatment of liver diseases as a hepatoprotective agent. It also has choleretic, cholelitholytic, hypolipidemic, hypocholesterolemic and immunomodulatory effects.

Enterohepatic circulation

The circulation of bile acids consists of their continuous movement from hepatocytes into the intestinal lumen and the reabsorption of most of the bile acids in the ileum, which conserves cholesterol resources. 6-10 such cycles occur per day. Thus, a small amount of bile acids (only 3-5 g) ensures the digestion of lipids received during the day. Losses of about 0.5 g/day correspond to daily cholesterol synthesis de novo.

Not a single process of complete digestion is complete without a special liquid produced by our body - bile. Its deficiency leads to impaired absorption of food, especially fat, and excess can even affect brain activity: in a sense, the expression “bilious person” sometimes has a purely physiological basis.

What is bile, where is it produced, its composition

Bile is a greenish or yellow-brown biological fluid that is produced by liver cells.

Bile is a biological fluid with a specific odor. It can be of varying thickness, yellow-brown or greenish in color and has a distinct bitter taste.

Bile is produced in liver cells - hepatocytes. It is quite liquid and has a light shade, for example, yellow. The liver continuously produces bile. Then it flows through special ducts into the reservoir - the gallbladder, which is a hollow sac with a capacity of 80-120 ml. Here it becomes more concentrated and viscous, and its color changes to darker, for example, brown or green. Due to the fact that bile produced directly in the liver differs in its physicochemical characteristics from that stored in the gallbladder, in medicine it is customary to separate hepatic and gallbladder bile separately.

The main differences between cystic and hepatic bile:

In addition, bile contains various proteins, metal ions, enzymes and other biologically active substances.

Food stimulates the contraction of the gallbladder, as a result of which bile flows through the common bile duct into the duodenum, where it mixes with the rest of the intestinal juice and pancreatic secretions.

Individual components that make up bile

Bilirubin and biliverdin. is formed from hemoglobin molecules that enter the blood after the death of red blood cells. It is he who gives the appropriate color to the bile, because it itself has a red-yellow color. Biliverdin has a green tint and is found in bile in small quantities. Oxidizing in the intestines, bile pigments turn stool brown.

If for some reason a lot of bilirubin accumulates in the blood, it gives a yellow tint to the skin, eyeballs and changes the color of urine, which becomes similar to beer. In the body, bilirubin is present in two main forms - bound and unbound with glucuronic acid. Unbound (indirect) bilirubin in large quantities can penetrate the brain cells, staining its various parts and leading to a change in mental state in adults and a decrease in mental abilities in newborns.

Bile acids. This is a series of organic acids that are necessary to emulsify fats. Without emulsification, the process of their absorption in the intestines is impossible. Excreted during the day in the amount of 15-30 g, the overwhelming amount of these acids is absorbed back, and only 0.5 g is excreted in the feces.

Pathological inclusions

Microorganisms and protozoa. Normally, bile is sterile. However, in some diseases, microorganisms or protozoa penetrate primarily from the intestines. The result is inflammation of the gallbladder. In this case, Proteus, Enterobacteriaceae, Klebsiella, Escherichia coli and even can be detected.

Microliths and stones. They are formed if the chemical composition of bile is disrupted: it should become more concentrated and saturated with cholesterol and bile salts.

Leukocytes, cells of the mucous membranes (epithelium). Normally present in small quantities. Their increase indicates inflammation of the gallbladder.

Functions of bile

Stagnation of bile in the gallbladder and insufficient release into the duodenum can lead to abdominal pain.

The main functions of bile:

fat emulsification;
increased activity of pancreatic enzymes;
normalization of fat absorption;
increased absorption of proteins and carbohydrates;
stimulation of intestinal motility;
participation in the renewal of cells of the intestinal mucosa;
neutralization of the effect of gastric juice, including pepsin;
participation in the absorption of cholesterol, calcium salts, fat-soluble vitamins, amino acids.

In case of disruption of the production and flow of bile into the intestines, the following digestive disorders are observed:

varying intensity (due to poor neutralization of gastric juice, it occurs, which causes pain);
bloating;
vitamin deficiency;
general weakness.

A striking example of such a condition is that which occurs after removal of the gallbladder.

How is bile examined?

To find out your bile composition, you should undergo duodenal intubation. To do this, after special preparation of the patient, a probe is inserted into the duodenum and the contents of the lumen of this intestine are taken for analysis, which is extracted in 5 phases:

Fraction “A” is a mixture of bile with duodenal juice (20-30 minutes).
Closing phase of the sphincter of Oddi. There is no bile in the contents (up to 6 minutes).
Bile flow from extrahepatic bile ducts (3-4 minutes).
Portion “B” – bladder bile (20-30 minutes).
Portion “C” – liver bile (remaining time after the end of phase No. 4).

As a rule, a referral for duodenal intubation can be obtained from a general practitioner, family doctor, gastroenterologist or surgeon.

At the doctor’s discretion, this procedure is usually prescribed for diseases of the liver, gall bladder, gastroduodenitis, etc. It must also be undergone in a comprehensive examination with ultrasound or MRI if the following complaints appear:

pain in the right hypochondrium;
change in color of stool;
appearance of skin, sclera, palms;
digestive disorders - bloating, flatulence;
, nausea, belching, etc.

Bile and character

Ancient scientists considered bile to be as important a fluid in the body as blood. They believed that an excess of light bile in the blood leads to a person becoming unbalanced and hot-tempered (choleric), and dark bile leads to depression and a gloomy mood (melancholy). Of course, such views turned out to be wrong.

However, if one of the components of bile, unconjugated bilirubin, enters the blood in large quantities, it can cause a number of pathological effects:

strong ;
discolored stool, dark urine;
change in the general condition of a person - irritability, increased weakness and fatigue.

In severe cases, toxic encephalopathy may develop, manifested by inhibition of all brain functions up to the development of coma.

How lifestyle can affect the composition of bile

With an increased level of bile components in the blood of a person, painful itching of the skin bothers him.

If bile remains in the gallbladder for a long time, it becomes more concentrated, and under unfavorable circumstances the risk increases