The main function of the liver as a digestive gland is. Liver

06.03.2020

The liver, being the largest human gland (can reach up to 2 kg), performs a number of vital functions. In the digestive system, everyone knows that its main role is the production of bile, without which most of food products simply will not be broken down (absorbed), but this is far from its only purpose. What other functions of the liver exist and how do they affect the human body? To understand this issue, first, you need to determine its structure, location in the body.

The liver in the human body: structure and location

It is located in the right subcostal cavity, slightly capturing the left side. This organ consists of many lobules, similar to microscopic prisms (up to 2 mm), with a very complex structure. A vein with a certain number of crossbars, which consist of 2 rows of cells, passes through the central part of each lobule. These cells also produce bile, which forms large channels through the bile capillary, which combine into the bile stream. Bile flow distribution: gall bladder (the lateral branch gets there), the duodenum (for example, bile is transported to the intestines, participating in the digestive act). So, having an idea of \u200b\u200bthe structure, location of this organ, you can safely start studying its main functions, which can be divided into two main blocks: digestive and non-digestive.

Digestive functions

Bile secretion is perhaps one of the most basic and well-known functions of the liver. Bile is a yellowish-green liquid that is produced by the liver, providing a change from gastric to intestinal digestion. Bile pigments are constantly generated by the liver through the cellular breakdown of hemoglobin.
This liquid performs a number of essential digestion processes:

emulsification of fats (in simple words, the process of mixing fat with water) with a subsequent increase in their area for joint hydrolysis with lipase (assimilation of fatty acids, fats themselves and fat-soluble vitamins);
dissolving lipid hydrolysis products, promoting their absorption and re-synthesis;
a significant increase in the activity of intestinal enzymes (including lipase);
increased hydrolysis and absorption of products of protein, carbohydrate nature;
participation in the absorption of cholesterol, amino acids, salts;
change in the acidity of gastric juice;
maintaining normal intestinal motility.

In the absence of the need to breakdown food that enters the stomach, bile accumulates in the gallbladder with increased concentration. Therefore, doctors often use the concepts of bile
hepatic and cystic. The secretion of bile (its amount) in all people occurs in different ways. However general principle is this: the sight, smell of food, its direct intake causes relaxation of the gallbladder, followed by contraction - a small dose of bile enters duodenum... Then, after emptying the gallbladder, bile begins to flow from the bile ducts, only then from the liver. Healthy body a person is able to produce 0.015 liters of bile per day per kilogram of weight.

Non-digestive functions

Detoxification function
The liver is a kind of barrier when harmful substances enter the body. The protective functions of the liver are especially useful for us when:
- inactivation of toxins (they can enter with food, occur in the intestine when its microflora changes);
- neutralization of nitrogenous products (deamination), which are formed during the breakdown of proteins (indoles, phenols, ammonia);
- fight against microbes (about 80% of microbes that can enter human blood will concentrate in the liver).
It is necessary to monitor the level of glycogen in the blood, with a decrease in the content of which, the barrier functions in the liver significantly worsen.
Regulatory function
The liver is able to regulate blood glucose levels. With an increased sugar content, the liver produces with the subsequent deposition of glycogen. Then, if there is not enough sugar, the accumulated glycogen is broken down into glucose, which again enters the bloodstream, normalizing the amount of sugar.
Exchange function
The liver is actively involved in protein, carbohydrate, lipid, vitamin and water-salt metabolism.
The liver is capable of:
- synthesize blood proteins, cholesterol and lecithins;
- forms urea, glutamines and keratins;
- create the necessary conditions for normal blood clotting, dissolution of blood clots;
- synthesize vitamin A, acetone, ketone bodies;
- stock up on vitamins, throwing them into the blood as needed (A, D, K, C, nicotinic acid);
- trap Fe, Cl ions, bicarbonate salts (water-salt exchange).
Sometimes the liver is called a reserve warehouse, as well as a depot for the above reasons.
Immunological function (participation in human immune reactions, for example, in the inactivation of mediators that accumulate during allergic reactions).
Endocrine function, in which it is able to remove or provide the exchange of a number of thyroid hormones, steroid types, insulin.
Excretory (providing homeostasis, that is, the ability to self-regulate the human body, in case of any changes in state, even with blood restoration).
The hematopoietic function manifests itself most of all during the pregnancy of a woman during the formation of the fetus (a large amount of blood plasma proteins are synthesized to obtain hormones, vitamins). Also, this gland is able to accumulate large volumes of blood that can be thrown into the general vascular system with blood loss or shock situations, due to a sharp narrowing of the vessels supplying the liver.

Therefore, without a liver, as well as without a heart, the human body cannot exist. The liver takes part in many life-supporting processes, helps in times of stress and a sharp shortage of any useful substances. The processes of food digestion and metabolism are possible only with normal liver function (retention, processing, distribution, assimilation, destruction, formation of a number of substances).

Liver dysfunction

Naturally, such an important human organ must be healthy and function normally. In this medical practice, a huge number of cases of liver disease are known. They can be classified into the following groups:

Damage to liver cells due to inflammatory (purulent) processes.
Mechanical damage (changes in its shape, structure, tears, open or gunshot wounds).
Diseases of the blood supplying hepatic vessels.
Lesions of the internal bile ducts.
The emergence of tumor (cancer) diseases.
Infectious diseases.
Abnormal and pathological changes in the liver (this also includes hereditary diseases).
Changes in liver function with pathology of other organs.
Functional (structural) tissue disorders, which often provoke insufficiency, cirrhosis.
Diseases caused by autoimmune viruses.

It is worth noting that any disease from the above will be accompanied by insufficiency and lead to cirrhosis.

Therefore, do not "put it off" if you notice any signs of liver dysfunction!

The main signs of liver dysfunction

1st sign. Unwanted irritability and behavior changes. Research by scientists and specialists in this field has shown that 95% of angry and irritable people suffer from some kind of liver disease. Moreover, most people find an excuse for themselves in daily stress at the everyday level, although these are two interrelated processes. On the one hand, impaired liver functions cause irritability in general, and, on the other hand, excessive anger, aggression contributes to the development of liver diseases.
2nd sign. Overweight and cellulite. This will unambiguously indicate metabolic disorders (prolonged intoxication of the body).
3rd sign. Reduced arterial pressure even in young people. That is, hypotensive patients are at risk, they are advised to pay special attention to their liver.
4th sign. The formation of vascular networks and varicose veins. Here, too, everything is not so simple, the previous sign is interconnected in this. If you start to actively raise the pressure and thereby get rid of varicose veins, then you can provoke the rapid development of hypertension. However, if vascular diseases such as varicose veins, hemorrhoids are observed in patients with high blood pressure, then this is already very running process with abnormal liver function, including.
5th sign: improper skin pigmentation and the appearance of "age" spots. The deposition of subcutaneous toxins will indicate a lack of antioxidants and the inability of the liver to perform protective and metabolic functions.
Sign 6: excessive frequency colds... This, most often, indicates poor microflora and intestinal motility against the background of intoxication of the body (the liver can no longer eliminate all toxins). So, toxins, reaching the liver and not being rendered harmless there, enter the respiratory system, negatively affect the immune system.
Sign 7: stool disorders (most patients experience constipation). Normal bile flow contributes to the absence of difficulty with stool.
Sign 8: pains concentrated on the right under the ribs. This symptom is not as popular as the rest (observed on average in 5% of patients), however, pain in this area will indicate impaired bile flow (problems with its outflow).
9th sign: long-term exposure to xenobiotics ( drugs synthetic nature) provokes liver dysfunctions not immediately, but over time, especially with regular intake.
Sign 10: improper and irregular nutrition (3 meals a day is not an indicator of a correct diet, for those who want to have a healthy liver, it is advisable to eat about 5 times a day in small portions). It is also necessary to monitor the regularity of the consumption of vegetable fiber. It will not only improve the intestinal microflora, but also contribute to the normal synthesis of vitamins.
Sign 11: dry skin, especially if this process is accompanied by hair loss. This indicates improper digestibility of food and a violation of the barrier function of the liver.
Sign 12: lack of exogenous cholesterol with its subsequent accumulation in the vascular walls (signs of atherosclerosis development). It should be understood that an excess of carbohydrates in the diet, which is often observed with vegetarianism, will provoke bile stagnation and the accumulation of cholesterol. The result can be not only atherosclerosis, but also non-alcoholic liver steatohepatitis. Although the main cause, fatty foods and alcohol, as such, have not been over-consumed.
Sign 13: blurred vision, especially at dusk. Normal vision can only be with a sufficient amount of vitamin A, for which the liver is responsible. Plant fiber can again come to the rescue, in addition to binding toxins, it will significantly reduce the consumption of this vitamin A and its provitamins.
Sign 14: reddened palms. The size of the areas of redness and their saturation can tell about the intensity of irritation in the liver tissues.
Sign 15: changes in the results of tests that control the condition of the liver. Often this will indicate profound changes in the normal functioning of the liver.

Few people know, however, the causes of increased fragility of bones and the development of osteoporosis may be associated not with a reduced intake of calcium, but due to its improper absorption. When digesting, food must be processed with bile so that the small intestine can absorb fat and calcium. If fat is not absorbed, then it will settle on the intestinal walls. Then, along with other waste, it will enter the large intestine, split a little, but most of it will still be excreted along with the feces (if the feces remain in the water at the time of emptying, this may indicate insufficient secretion of bile, because fat is lighter water, which means the waste is oversaturated with unsplit fat). The connection is interesting because calcium cannot be absorbed without fat. The body will take the lack of this substance from the bones in order to make up for it.

If we talk about the appearance of stony formations in the liver or gallbladder, then a person must have a stool disorder (feces can acquire orange, yellow), premature aging and self-destruction of the body will begin, because the body will be unable to ensure its normal functioning. The main reason for the appearance of stones in the biliary system is a violation of the metabolic processes of bilirubin and cholesterol, which can occur when: inflammatory processes, dietary disorders (predominance of fats in the diet, especially pork), hormonal imbalance, viral or other diseases.
Advice: if any sign is already bothering a person, it is recommended to immediately visit a gastroenterologist. In this case, you can prevent many liver diseases in time.

Keeping the liver healthy

In addition to common viruses, infections and pathologies, very often the person himself is to blame for the development of liver diseases. The environment (ecology, food quality) also has an indelible effect on the liver, but anyone who does not want to have liver problems should take care of themselves. It is necessary to monitor compliance with labor protection rules in hazardous industries. Foods that have undergone any additional chemical processing make it incredibly difficult for the liver to function. Do not abuse alcoholic beverages. Additionally, always monitor the handling of medical equipment. Treat with increased attention to donated blood (it can be the source viral hepatitis). Try to take care of your diet as much as possible and do not treat all diseases with pills - this can have a short-term improvement, but in the future it will contribute to the development of liver disease. It will not be superfluous to remind once again that self-medication and improper treatment of pathologies of other organs can lead to secondary liver damage.

Remember that the liver is the connecting element between the two most important systems of the human body (blood supply and digestion). Any disturbances in the functioning of this gland will contribute to the development of heart, stomach and intestinal diseases.
And the simplest advice from doctors: if between 5-7 in the morning healthy man drinks at least half a glass of water or herbal decoction, night bile (especially toxic) will leave the body and will not interfere with the normal functioning of the liver until the end of the day.

1. Participates in protein metabolism.

2. The liver is involved in the metabolism of carbohydrates.

3. The liver participates in fat metabolism by the action of bile on fats in the intestine, as well as directly by the synthesis of lipoids (cholesterol) and the breakdown of fats with the formation of ketone bodies.

4. The liver is involved in the metabolism of vitamins.

5. The liver takes part in the exchange of steroid hormones and other biologically active substances.

6. The liver plays an important role in maintaining homeostasis, due to its participation in the exchange of hormones.

7. The liver is involved in the metabolism of trace elements. It influences the absorption of iron in the intestine and deposits it. The liver is a depot of copper and zinc. She takes part in the exchange of manganese, cobalt, etc.

8. The protective (barrier) function of the liver is manifested in the following. First, microbes in the liver undergo phagocytosis. Secondly, the liver cells neutralize toxic substances of an endogenous and exogenous nature.

9. In the liver, substances are synthesized, involved in blood coagulation and components of the anticoagulant system.

10. The excretory function of the liver is associated with bile formation, since the substances excreted by the liver are part of the bile. These substances include bilirubin, thyroxine, cholesterol, etc.

11. The liver is a blood depot.

12. The liver is one of essential organs heat products.

13. The participation of the liver in digestion processes is provided mainly by bile, which is synthesized by liver cells.

Bile composition.Bile is not only a secret, but also an excretion. Together with bile, various endogenous and exogenous substances are excreted from the body. Bile also contains proteins, amino acids, vitamins and other substances. Bile has little enzymatic activity; pH of hepatic bile 7.3-8.0.

The qualitative originality of bile is determined by the bile acids, pigments and cholesterol in it.

Main quantity bile acids and their saltscontained in bile in the form of compounds with glycocol (80%) and taurine (20%). When eating food rich in carbohydrates, the content of glycocholic acids in bile increases, with a high-protein diet - taurocholic acids. Bile acids and their salts determine the main properties of bile as a digestive secretion.

Bile functions.

1. Participates in digestion processes:

Emulsifies fats, thereby increasing the surface for hydrolysis by lipase;

Dissolves fat hydrolysis products, thereby facilitating their absorption;

Increases the activity of enzymes (pancreatic and intestinal), especially lipases;

Neutralizes acidic stomach contents;

Inactivates pepsins;

Promotes the absorption of fat-soluble vitamins, cholesterol, amino acids and calcium salts;

Participates in parietal digestion, facilitating the fixation of enzymes;

Strengthens motor and secretory function small intestine.

2. Stimulates bile formation and bile secretion.

3. Participates in the hepatic-intestinal circulation of bile components - bile components enter the intestines, are absorbed into the blood, and are re-incorporated into bile.

4. Bile has a bacteriostatic effect - it inhibits the development of microbes, prevents the development of putrefactive processes in the intestine.

Dynamics of bile formation and bile secretion.A person produces about 500-1500 ml of bile per day (an average of 10.5 ml per 1 kg of body weight). The process of bile formation (bile secretion, or choleresis) goes on continuously, and the flow of bile into the duodenum (bile secretion, or cholekinesis) - periodically, mainly in connection with food intake. On an empty stomach, bile enters the intestines in accordance with hungry periodic activity. During periods of rest, it goes to the gallbladder, where it concentrates during deposition and somewhat changes its composition. Therefore, it is customary to talk about two types of bile - hepatic and gallbladder.

A good liver function ensures the health of the entire body as a whole.

The functions of the liver are numerous, but there are two irreplaceable ones: it purifies all the blood, which saturates every cell in our body, and, taking part in the process of digestion, helps to obtain the energy necessary for life. Moreover, both functions of the liver are performed not simultaneously, but in accordance with natural biological rhythms. Cleansing the blood from toxins and their accumulation in bile occurs at night, when all other body systems are at rest. Therefore, if a person eats breakfast between 5 and 7 o'clock in the morning or at least drinks half a glass of juice, herbal decoction, nightly toxic bile will enter the digestive system, and then the toxins will not poison him all day.

In this way, you can prevent constipation, hemorrhoids, gastritis, biliary dyskinesia, cholelithiasis, cholangitis, uric acid diathesis.

Every day, the liver secretes from a pound to a kilogram of bile, which is simply necessary for digestion.
The liver also serves as a link connecting the two systems - blood circulation and digestion. If this complex mechanism upset, heart, stomach and intestines aches.

When a pregnant woman drinks a lot of coffee, drinks alcohol, smokes, takes antibiotics, she risks giving birth to a child with an already diseased liver.

These are just the basic functions of the liver. And there are more than five hundred of them!

Regulation of metabolism

It takes part in the processing of fats and proteins, it stores nutrients, including glycogen, which is needed during stress. For other systems, it seems to serve as a "cover" from the strong release of norepinephrine and adrenaline.

The protective functions of the liver are irreplaceable in the processes of food digestion and metabolism. Complex chemical reactions take place in it. The liver detains, processes, distributes, assimilates and destroys substances that enter it from various organs (spleen, intestines) and tissues. At the same time, it produces new products from these substances that the body needs.

In digestion, bile plays an important role, which is produced by the liver. Bile is formed non-stop: during the day, it is released at least 500 ml and at most 1.2 liters. When there is no digestion process, it accumulates in a very concentrated form in the gallbladder. Its saturation is explained by the very small volume of the gallbladder: no more than 30-40 ml. In liver cells, bile is formed from those substances that come from the blood. In other words, bile pigments are the result of the breakdown of hemoglobin. Both bile pigments and acids are the most important components that make up bile. It also contains mucin, cholesterol, soaps, lecithin, inorganic salts and fats.

Bile production is also stimulated by humoral factors. These include those products that are obtained from the processing of fats and proteins, gastrin, as well as bile itself.
Excretion of bile is regulated by humoral and neuroreflex mechanisms. The vagus and sympathetic nerves transmit the influence of stimuli (conditioned and unconditioned) to the bladder and its ducts. When the vagus nerve is weakly irritated, then in general bile duct the sphincter relaxes, and the muscles of the bladder contract. Only then can bile enter the duodenum.

When the vagus nerve becomes more irritated, this leads to the opposite effect - the sphincter contracts, and the muscles of the bladder relax and bile accumulates in it. Artificial stimulation of the sympathetic nerve produces the same effect as irritation vagus nerve.

The most important humoral regulator of bile excretion - cholecystokinin is formed in the duodenum, in its mucous membrane. Thanks to it, the gallbladder contracts and empties during digestion.
The outflow of bile begins five to ten minutes after eating. The gallbladder is completely emptied three to five hours after the last meal. In small portions, bile from it enters the intestines every hour or two. Its release increases significantly during the simultaneous entry of food into the intestine and depends on the nature of the nutrients.

The functional purpose of bile is that it activates lipase (enzyme), emulsifies fats (already emulsified fats are affected by lipase), while increasing the area of \u200b\u200btheir collision with the enzyme, due to which its effect is significantly enhanced.

Absorption and breakdown of fats

Bile is important in the absorption of fat. Fatty acids are one of the products of their breakdown. They can be absorbed only after they combine with bile acids. The absorption of these compounds is due to their good solubility in water. The motor function of the intestines is also stimulated by bile.

Regulation of blood glucose levels

Participation in the metabolism of fats, carbohydrates and proteins is also included in the function of the liver. It regulates the stability of blood sugar levels. When the concentration of glucose in the blood increases, glycogen is formed from it in the liver and then deposited. As soon as the sugar content in the blood drops, glycogen is broken down in the liver into glucose, which is returned to the bloodstream, and thus the sugar content in it returns to normal.

Protein metabolism

The function of the liver also includes the effect on protein metabolism. It retains protein more than other organs (by 30-60%). There are also some protein substances that, coming from the alimentary canal to the portal vein, are processed in it and defatted. Plasma proteins - albumin, fibrinogen and others - are also formed in the liver. It produces antithrombin and prothrombin, which are necessary for blood clotting. Therefore, with a liver ulcer, the process of blood clotting is disrupted.

Vitamin synthesis

The functions of the liver are directly related to participation in vitamin metabolism. Vitamin A is synthesized in this organ, niacin and vitamin K are deposited.

Water-salt exchange

Water-salt metabolism also does not occur without the participation of the liver. It is in it that ions of iron, chlorine, bicarbonates are retained.
She also participates in the metabolism of fats. Fat is deposited in it, which first enters the portal vein, and then passes into an unsaturated form, which is easily oxidized. From the number of fatty acids in this organ, substances such as acetone, glucose, ketone bodies are formed. Cholesterol and lecithin are also synthesized from fatty acids in it.
During the development of the embryo, the liver plays the role of a blood-producing organ.

Protective functions

The protective functions of the liver consist in the ability to neutralize nitrogenous toxic products resulting from the breakdown of proteins - indole, phenol, ammonia and skatole. They are converted to urea and excreted in the urine. Due to the ability to phagocytosis, the stellate cells of the capillaries fight against microbes that enter the body. It was found that after the introduction of microbes into the blood, only half a percent of them accumulate in the brain tissues, six percent in the lungs, and their number in the liver reaches eighty percent. It should be noted that the detoxifying effect of the liver is especially pronounced if it is saturated with glycogen. If its level falls, the protective functions of the liver also decrease.

The human organ is the liver. It is unpaired and located on the right side abdominal... The liver has about 70 different functions. All of them are so important for the vital activity of the body that even a slight disruption in its functioning leads to serious diseases. In addition to participating in digestion, it cleanses the blood of poisons and toxins, is a storehouse of vitamins and minerals and performs many more functions. To help this organ work without interruption, you need to know what is the role of the liver in the human body.

Basic information about this organ

The liver is located in the right hypochondrium and takes up a lot of space in the abdominal cavity, because it is the largest internal organ... Its weight ranges from 1200 to 1800 grams. In shape, it resembles a convex mushroom cap. It got its name from the word "stove", since this organ is very heat... The most complex chemical processes are constantly going on there, and work goes on without interruption.

It is impossible to unequivocally answer the question of what is the role of the liver in the human body, because all the functions it performs are vital for it. Therefore, this organ has regenerative abilities, that is, it can regenerate itself. But the termination of its activity leads to the death of a person in a couple of days.

Protective function of the liver

More than 400 times a day, all the blood passes through this organ, clearing itself of toxins, bacteria, poisons and viruses. The barrier role of the liver is that its cells break down all toxic substances, process them into a harmless water-soluble form and remove them from the body. They work like a complex chemical laboratory, neutralizing toxins that enter the body with food and air and are formed as a result of metabolic processes. What poisonous substances does the liver cleanse the blood of?

From preservatives, dyes and other additives found in food.

From bacteria and microbes that enter the intestines, and from their waste products.

From alcohol, drugs and other toxic substances that enter the bloodstream with food.

From exhaust gases and heavy metals from the ambient air.

From an excess of hormones and vitamins.

From toxic metabolic products such as phenol, acetone or ammonia.

Digestive function of the liver

It is in this organ that proteins, fats and carbohydrates coming from the intestine are converted into an easily digestible form. The role of the liver in the digestion process is enormous, because it is there that cholesterol, bile and many enzymes are formed, without which this process is impossible. They are released into the intestines through the duodenum and aid in the digestion of food. Particularly important is the role of bile, which not only breaks down fats and promotes the absorption of proteins and carbohydrates, but also has a bactericidal effect, destroying the pathogenic microflora in the intestines.

The role of the liver in metabolism

Carbohydrates supplied with food are converted only in this organ into glycogen, which in the form of glucose enters the bloodstream as needed. The gluconeogenesis process provides the body with the required amount of glucose. The liver controls the level of insulin in the blood based on the person's needs.

This organ is also involved in protein metabolism. It is in the liver that albumin, prothrombin and other proteins are synthesized that are important for the life of the body. Almost all cholesterol involved in the breakdown of fats and the formation of some hormones is also formed there. In addition, the liver takes an active part in water-mineral metabolism. It can accumulate up to 20% blood and

serves as a repository of many minerals and vitamins.

Participation of the liver in the process of hematopoiesis

This organ is called the "blood depot". In addition to the fact that up to two liters of it can be stored there, hematopoiesis processes proceed in the liver. It synthesizes globulins and albumin, proteins that provide its fluidity. The liver is involved in the formation of iron, which is necessary for the synthesis of hemoglobin. In addition to toxic substances, this organ breaks down red blood cells, resulting in the production of bilirubin. It is in the liver that proteins are formed that perform transport functions for hormones and vitamins.

Storage of useful substances

Speaking about the role of the liver in the human body, it is impossible not to mention its function of accumulating substances necessary for vital activity. What is the repository of this organ?

1. This is the only storage site for glycogen. The liver stores it and releases it into the blood as glucose as needed.

2. About two liters of blood are kept there and used only in case of severe blood loss or shock.

3. The liver is a storehouse of vitamins necessary for the normal functioning of the body. Especially a lot of vitamins A and B12 are stored in it.

4. This organ forms and accumulates cations of metals necessary for the body, such as iron or copper.

What can the abnormalities in liver function lead to?

If this organ for some reason cannot work correctly, then various diseases... You can immediately understand what is the role of the liver in the human body, if you see what the disturbances in its work lead to:

Decreased immunity and persistent colds;

Blood clotting disorders and frequent bleeding;

Severe itching, dry skin;

Hair loss, acne;

The emergence of diabetes and obesity;

Various gynecological diseases, such as early menopause;

Digestive disorders, manifested by frequent constipation, nausea and decreased appetite;

Nervous disorders - irritability, depression, insomnia and frequent headaches;

Disorders of water exchange, manifested by edema.

Very often, the doctor treats these symptoms without noticing that the cause is liver damage. There are no nerve endings inside this organ, so a person may not experience pain. But everyone should know what role the liver plays in his life and try to maintain it. It is necessary to give up alcohol, smoking, spicy and fatty foods. Limit the use of drugs, foods containing preservatives and dyes.

The importance of the liver in the body is great: it takes part in the processes of digestion and metabolism, has a protective function, and complex chemical reactions take place in it; it processes, detains, redistributes, assimilates and destroys various substances that enter it from the intestines, spleen and other organs and tissues. At the same time, it synthesizes from these substances new products that the body needs.

The liver plays an important role in carbohydrate metabolism: it regulates the constancy of blood sugar. As soon as the concentration of glucose in the blood rises, glycogen is formed from glucose in the liver, which is stored in a reserve. With a decrease in blood sugar, glycogen in the liver breaks down to glucose, which enters the bloodstream, and thus the sugar content in it is leveled.

Liver function is also associated with protein metabolism. She keeps 30-60% more proteinthan other organs. It processes and degreases some of the protein substances that enter the portal vein from the digestive tract. In the liver, blood plasma proteins are formed - fibrinogen, albumin, etc. It produces prothrombin and antithrombin necessary for blood clotting. With liver damage, the blood clotting process is disrupted.

The liver takes part in the exchange of vitamins. Vitamin is synthesized in it AND and stored in vitamins A, D, K, as well as nicotinic acid. The liver contains one of the hematopoietic factors, which contains vitamin In p.

The liver participates in water-salt metabolism, ions of chlorine, iron, bicarbonates, etc. are retained in it.

The liver also takes part in the metabolism of fats. It stores fat that enters through the portal vein and easily transforms into an unsaturated, easily oxidized form. A number of fatty acids in the liver form substances such as glucose, acetone, ketone bodies. In it, lecithin and cholesterol are synthesized from fatty acids.

During intrauterine development, the liver plays the role of a hematopoietic organ.

The protective function of the liver lies in the fact that poisonous nitrogenous decomposition products of proteins - phenol, indole, skatole and ammonia are rendered harmless in it, which is converted into urea, excreted in the urine. The stellate cells of the liver capillaries are capable of phagocytosis, carrying out the fight against microbes that have entered the body. When microbes were introduced into the blood, it was found that about 0.5% of them accumulate in the brain tissues, 6% in the lungs, and 80% in the liver. It should be noted that the detoxifying function of the liver is clearly manifested in the case when the liver is rich in glycogen. When it decreases, the protective function of the liver decreases.

An important role in digestion is played by the liver produced bile. Bile is formed continuously, 1000-1800 ml are secreted per day (about 15 ml per 1 kg of body weight). Bile formation process - bile secretion (choleresis) - is carried out continuously, and the flow of bile into the duodenum - bile secretion (cholekinosis)- periodically, mainly in connection with food intake. On an empty stomach, bile almost does not enter the intestine, it is sent to the gallbladder, where, when deposited, it concentrates and somewhat changes the composition, therefore it is customary to talk about two types of bile - hepatic and cystic.

Bile is formed in liver cells from substances coming from the blood. So, bile pigments are formed from the breakdown products of hemoglobin. The most important constituents of bile are bile acids, their salts (cholates) and bile pigments. In addition, it contains cholesterol, lecithin, mucin, fats, soaps and inorganic salts.

Bile production is stimulated by such humoral factorssuch as gastrin, meat extracts, processed proteins and fats, and bile itself.

The sight, smell of food, preparation for its intake and the actual intake of food cause a change in the activity of the biliary apparatus; at the same time, the gallbladder begins to relax and then contracts. A small amount of bile through the sphincter of Oddi enters the duodenum. This period of the primary reaction of the biliary apparatus lasts 7-10 minutes. It is replaced by the main evacuation period (or the period of emptying the gallbladder), during which the contraction of the gallbladder alternates with relaxation, and bile passes into the duodenum through the sphincter of Oddi - first from the common bile duct, then the gallbladder, and then the hepatic.

Egg yolks, milk, meat and fats are powerful stimulants of bile secretion.

Bile secretion is regulated by neuro-reflex and humoral mechanisms. The influence of conditioned and unconditioned stimuli is transmitted to the bladder and its duct along the vagus and sympathetic nerves. With a weak irritation of the vagus nerve, the sphincter of the common bile duct relaxes and the muscles of the bladder contract, this ensures the flow of bile into the duodenum.

Severe irritation of the vagus nerve causes the opposite effect - contraction of the sphincter and relaxation of the muscles of the bladder, which leads to the accumulation of bile in the bladder. Stimulation of the sympathetic nerve has the same effect as severe irritation of the vagus nerve.

An important humoral regulator of bile secretion is cholcystokinin, which is formed in the mucous membrane of the duodenum and causes contraction of the gallbladder, its emptying during digestion.

The release of bile begins 5-10 minutes after eating. After 3-5 hours, the gallbladder is completely emptied. From it, bile enters the intestines in small portions every 1-2 hours. Its secretion increases significantly when food enters the intestines and depends on the nature of the nutrients.

The value of bile lies in the fact that it activates lipase, emulsifies fats (lipase acts on emulsified fats), increases the surface of their contact with the enzyme, due to which the effect of the enzyme is significantly increased.

Bile takes part in the absorption of fats. Fatty acids - one of the end products of fat breakdown - are absorbed only after combining with bile acids. These compounds dissolve in water, so they are well absorbed. Bile stimulates the motor function of the intestines.

Disorders of cholesterol and bile acid metabolism. The precipitation of cholesterol occurs when the ratio of "cholate / cholesterol" and "lecithin / cholesterol" decreases, therefore, the formation of stones is promoted by an increase in the concentration of cholesterol in the bile and a decrease in the content of lecithin and cholates. Risk factors:

obesity (increased excretion of cholesterol in the bile);
severe hyperlipidemia;
violation of a balanced diet (fatty meat, eggs, oil and

other foods high in cholesterol);

hereditary predisposition;
diabetes;
pregnancy;
resection of the small intestine (the absorption of bile acids is impaired

due to a decrease in the functional surface of the intestine).