What does the liver do in the human body? Liver functions

The liver is a unique organ in the human body. It performs a number of functions that can be compared to a "chemical factory". With its participation, a variety of chemical transformations occur with substances delivered to the body. What are the main functions of the liver for the body to function properly? In fact, the human liver performs a number of essential functions necessary for existence, such as detoxification, storage, metabolism.

Detoxification: Everyone knows that the liver cleanses the body of toxins that are absorbed from the intestines through the blood along with metabolic products. It neutralizes alcohol (), caffeine, drugs, excessive hormones, preservatives, plant and animal toxins. A number of complex chemical reactions take place in the liver, as a result of which harmful compounds are neutralized.

Storage: Glycogen, fat, iron and vitamins A, B12, D, F and small amounts of vitamin C accumulate here. These compounds enter the bloodstream as required by the system.

Metabolism: biochemical changes in proteins, fats, carbohydrates, trace elements, vitamins occur in the liver. Glucose is absorbed in the intestines, then converted into glycogen, the reserves of which regulate blood glucose levels. Fats are raw materials for the production of cholesterol and lipoproteins. Cholesterol, in turn, is the raw material for the production of bile. The liver converts sugar into fat.

The human liver and its tasks

The liver of an adult weighs approximately 1.5 - 2 kg (2% of body weight). It is located under the diaphragm in the upper right abdomen. A healthy organ has a dark brown color, soft and elastic tissue. It consists of two parts: right and left. Both shares can be easily distinguished, because. they are separated by a stripe. Under a microscope, you can see that the liver consists of small hepatic lobules (hexagonal), which are approximately 2 ml in size. The lobules are made up of liver cells (hepatocytes).

The liver is not only the largest organ in the human body, but the largest gland. It not only produces bile, but is also responsible for metabolism, as it takes on the most important tasks in restoring food components such as fats, carbohydrates and proteins. In addition, it is involved in the regulation of hormones and immune system. Without this gland, it is impossible to survive.

The liver is a digestive organ due to its location. It plays an important role in the restoration of food components. About 1.5 liters of blood passes through it per minute. Approximately 25% is used to supply oxygen, the remaining 75% comes from the vessels of the gastrointestinal tract, which is enriched with nutrients, but also with toxins. The liver filters the blood to keep the body healthy.

Carbohydrate metabolism: One of the main tasks of the liver is to maintain the balance of glucose in the body. Carbohydrates consumed with food are converted into glucose in the intestines, then enters the bloodstream and then the liver. It stores glucose and converts it when there is a shortage of glucose in the body.

Fat metabolism: Under the influence of lipase, fats are absorbed to glycerol and fatty acids. This process depends on the flow of bile and bile acids. It then breaks down into free bile acids and higher fatty acids. Free bile acids enter the liver and pass into the composition of bile. Higher fatty acids partially enter the blood. Most of the fatty acids and triglycerides are retained in the liver for further conversion.

Protein metabolism: the body needs proteins as the building blocks of cells and tissues. Already in the small intestine, protein is broken down into amino acids, which enter the liver through the bloodstream. Subsequently, the liver produces many different proteins, without which human organ ism cannot survive.

Blood cleansing: The main task of the liver is to cleanse the blood of toxic substances that the body does not need. These substances are transferred from the blood plasma directly to the liver cells, where they are converted (several steps). The end products of this transformation are removed from the body through the kidneys.

The most common exogenous toxins that the liver neutralizes are: alcohol, tobacco, drugs. An endogenous substance is, for example, bilirubin, which is eliminated from the blood and ultimately excreted in the stool. If this function is impaired, then symptoms of jaundice occur.

Main functions of the liver

Various functions of the liver are carried out by all liver cells, but in varying degrees. Their ability to perform complex tasks is extremely important for human life. Thus, the loss of 80% of the tissue of this gland is not compatible with life. However, it is capable of self-regeneration after acute and chronic damage.

Functions:

• bile formation (about 600 ml per day);
• neutralization of toxins;
• neutralization and removal of excess substances (hormones, vitamins), end products of metabolism;
• regulation of hormone levels (eg, aldosterone, adrenaline, estrogen, insulin);
• participation in digestion;
• conversion of ammonia to urea;
• storage of energy reserves (glycogen);
• carbohydrate metabolism;
• accumulation, storage and supply of certain vitamins;
• participation in the metabolism of vitamins (folic acid, A, C, B, D, K, E, PP); conversion of carotene to;
• synthesis of lipids, cholesterol, regulation of lipid metabolism; restoration of fat energy;
• synthesis of enzymes, hormones that are involved in the transformation of food;
• detoxification of endogenous and exogenous substances (alcohol, toxins, drugs);
• participation in immune functions;
• important role in blood flow;
• thermoregulation of the body;
• production of plasma proteins and blood coagulation factors.

Thus, the liver is an important part of the body, which performs much more functions than just processing substances from food. It is responsible for the production of substances that break down fats. In addition, it produces amino acids without which the body is not able to function, because. they have importance in protein production. The liver also produces cholesterol, both healthy and unhealthy.

In addition to the ability of the liver to produce various substances, it also performs the function of filtering. If harmful substances enter the body, it neutralizes and removes them from the body. In short, the most important function of the liver is to maintain proper balance in the body. It neutralizes harmful toxins, produces vital substances and removes waste products from the body.

Why is the liver so famous? What work does this giant organ do in our body (after all, in an adult, the weight of the liver reaches 2 kilograms!), And why is this work so important for our well-being?

The answer is simple. The liver is “both a granary and a health resort”, or rather, a “cleaning station” of our body, and a “laboratory” for the production of substances necessary for the body, and even a pantry where we store “emergency supplies for a rainy day”!

There are more than 500 items on the list of liver functions - but it has three main tasks.

Between the hepatocytes are bile ducts, outside they are surrounded by blood vessels. But there are almost no sensitive nerves in the liver - therefore, it does not hurt and copes with its difficult work "silently", and we sometimes do not realize how hard it is for her.

Often, for example, during the holidays, when we spend time at a plentiful festive table, - our liver is working with overload. Filters do not have time to cope with the flow of toxins, and the next morning we get out of bed broken, with a headache, without strength. Attributing all these symptoms to the festive "bust", we do not think about the liver - because it does not hurt! Meanwhile, one of the most important organs needs our help.

A proper diet, a reasonable attitude to medicines, timely intake of drugs to protect and restore the liver - all this will protect the working liver from wear and tear, help it recover from "shock" work and provide strength and energy to the whole body!

Let's take care of the liver - and help it take care of you for many years!

We suggest that you read the article on the topic: "What is the liver responsible for" on our website dedicated to the treatment of the liver.

Liver(lat. jecur, jecor, hepar, other Greek ἧπαρ) - a vital gland of external secretion of vertebrate animals, including humans, located in abdominal cavity(abdominal cavity) under the diaphragm and performing a large number of different physiological functions. The liver is the largest gland in vertebrates.

(1) right lobe, (2) left lobe, (3) caudate lobe, (4) quadrate lobe, (5) hepatic artery and portal vein, (6) lymph nodes, (7) gallbladder

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Liver anatomy

The liver consists of two lobes: right and left. In the right lobe, two more secondary lobes are distinguished: square and caudate. According to the modern segmental scheme proposed by Claude Quino (1957), the liver is divided into eight segments, forming the right and left lobes. The segment of the liver is a pyramidal section of the hepatic parenchyma, which has a fairly separate blood supply, innervation and outflow of bile. The caudate and square lobes, located behind and in front of the gates of the liver, according to this scheme correspond to SI and SIV of the left lobe. In addition, SII and SIII of the liver are isolated in the left lobe, the right lobe is divided into SV - SVIII, numbered around the gate of the liver in a clockwise direction.

Histological structure of the liver

The parenchyma is lobular. The hepatic lobule is the structural and functional unit of the liver. The main structural components of the hepatic lobule are:

• liver plates (radial rows of hepatocytes);
• intralobular sinusoidal hemocapillaries (between the hepatic beams);
• bile capillaries (lat. ductuli beliferi) inside the hepatic beams, between two layers of hepatocytes;
• (expansion of the bile capillaries when they exit the lobule);
• perisinusoidal space of Disse (slit-like space between the hepatic beams and sinusoidal hemocapillaries);
• central vein (formed by the fusion of intralobular sinusoidal hemocapillaries).

The stroma consists of an outer connective tissue capsule, interlobular layers of RVST (loose fibrous connective tissue), blood vessels, and the nervous apparatus.

Liver functions

The main internal organs of a human, front view. No. 4 - liver

• neutralization of various foreign substances (xenobiotics), in particular, allergens, poisons and toxins, by converting them into harmless, less toxic or more easily removed compounds from the body; the detoxification function of the fetal liver is insignificant, since it is performed by the placenta;
• neutralization and removal from the body of excess hormones, mediators, vitamins, as well as toxic intermediate and final products of metabolism, such as ammonia, phenol, ethanol, acetone and ketone acids;
• providing the energy needs of the body with glucose and converting various energy sources (free fatty acids, amino acids, glycerol, lactic acid, etc.) into glucose (the so-called gluconeogenesis);
• replenishment and storage of rapidly mobilized energy reserves in the form of glycogen and regulation of carbohydrate metabolism;
• replenishment and storage of the depot of some vitamins (especially large in the liver are the reserves of fat-soluble vitamins A, D, water-soluble vitamin B12), as well as the depot of cations of a number of trace elements - metals, in particular, iron, copper and cobalt cations. Also, the liver is directly involved in the metabolism of vitamins A, B, C, D, E, K, PP and folic acid;
• participation in the processes of hematopoiesis (only in the fetus), in particular, the synthesis of many blood plasma proteins - albumins, alpha and beta globulins, transport proteins for various hormones and vitamins, proteins of the blood coagulation and anticoagulation systems, and many others; the liver is one of the important organs of hematopoiesis in prenatal development;
• synthesis of cholesterol and its esters, lipids and phospholipids, lipoproteins and regulation of lipid metabolism;
• synthesis of bile acids and bilirubin, production and secretion of bile;
• also serves as a depot for a fairly significant volume of blood, which can be thrown into the general vascular bed in case of blood loss or shock due to narrowing of the vessels supplying the liver;
• synthesis of hormones (for example, insulin-like growth factors).

Features of the blood supply to the liver

Features of the blood supply to the liver reflect its important biological function of detoxification: blood from the intestines, containing toxic substances consumed from the outside, as well as waste products of microorganisms (skatol, indole, etc.) is delivered to the liver through the portal vein (v. portae) for detoxification. Further portal vein divides into smaller interlobular veins. arterial blood enters the liver through its own hepatic artery (a. hepatica propria), branching to the interlobular arteries. The interlobular arteries and veins eject blood into the sinusoids, where, thus, mixed blood flows, the drainage of which occurs into the central vein. The central veins drain into the hepatic veins and then into the inferior vena cava. In embryogenesis, the so-called. duct of arantia, which carries blood to the liver for efficient prenatal hematopoiesis.

Toxin Detox Mechanism

Neutralization of substances in the liver consists in their chemical modification, which usually includes two phases. In the first phase, the substance undergoes oxidation (detachment of electrons), reduction (addition of electrons), or hydrolysis. In the second phase, a substance is added to the newly formed active chemical groups. Such reactions are called conjugation reactions, and the addition process is called conjugation. Also, when toxic substances enter the liver, the area of ​​agranular EPS increases in the cells of the latter, which allows them to be neutralized.

Liver disease

Diagram of the structure of the hepatic lobule

Cirrhosis of the liver- chronic progressive liver disease, characterized by a violation of its lobular structure due to the growth of connective tissue and pathological regeneration of the parenchyma; manifested by functional liver failure and portal hypertension.

The most common causes of the disease are chronic alcoholism (the proportion of alcoholic cirrhosis of the liver is different countries from 20 to 95%), viral hepatitis (accounts for 10-40% of all liver cirrhosis), the presence of helminths in the liver (most often opisthorchis, fasciola, clonorchis, toxocara, notocotylus), as well as protozoa, including Trichomonas.

The occurrence of benign adenomas, angiosarcomas of the liver, hepatocellular carcinoma are associated with human exposure to androgenic steroidal contraceptive and anabolic drugs.

The main symptoms of liver cancer:

• weakness and decreased performance;
• weight loss, weight loss, and then severe cachexia, anorexia.
• nausea, vomiting, sallow skin color and spider veins;
• complaints of a feeling of heaviness and pressure, dull pain;
• fever and tachycardia;
• jaundice, ascites and dilatation of the superficial veins of the abdomen;
• gastroesophageal bleeding from varicose veins;
• skin itching;
• gynecomastia;
• flatulence, intestinal dysfunction.

Aflatoxicosis

Aflatoxin B1

Extremely toxic and the strongest hepatocarcinogen.

Aflatoxicosis - acute or chronic intoxication with aflatoxins, the strongest hepatotoxins and hepatocarcinogens, occurs exclusively alimentary way i.e. through food. Aflatoxins are secondary metabolites produced by microscopic molds of the genus Aspergillus, in particular Aspergillus flavus and Aspergillus parasiticus.

Aspergillus affects almost all food products, but the main plant products are made from cereals, legumes and oilseeds such as peanuts, rice, corn, peas, sunflower seeds, etc. Acute aflatoxicosis occurs with a single use of contaminated (contaminated) food products with aspergillus - severe intoxication, accompanied by acute toxic hepatitis. With a sufficiently long use of contaminated food products, chronic aflatoxicosis occurs, in which hepatocellular carcinoma develops in almost 100% of cases.

Liver hemangiomas- anomalies in the development of liver vessels.
The main symptoms of hemangioma:

• heaviness and feeling of fullness in the right hypochondrium;
• dysfunction of the gastrointestinal tract (loss of appetite, nausea, heartburn, belching, flatulence).

• constant pain in the right hypochondrium;
• fast onset feeling of fullness and discomfort in the abdomen after eating;
• weakness;
• increased sweating;
• loss of appetite, sometimes nausea;
• shortness of breath, dyspeptic phenomena;
• jaundice.

• soreness;
• feeling of heaviness, pressure in the right hypochondrium, sometimes in the chest;
• weakness, malaise, shortness of breath;
• recurring urticaria, diarrhea, nausea, vomiting.

Other liver infections: clonorchiasis, opisthorchiasis, fascioliasis.

Liver regeneration

The liver is one of the few organs capable of restoring its original size even with only 25% of normal tissue remaining. In fact, regeneration occurs, but very slowly, and the rapid return of the liver to its original size is more likely due to an increase in the volume of the remaining cells.

Four types of liver stem/progenitor cells have been found in the mature liver of humans and other mammals, the so-called oval cells, small hepatocytes, liver epithelial cells, and mesenchymal-like cells.

Oval cells in rat liver were discovered in the mid-1980s. The origin of the oval cells is unclear. Possibly they originate from cell populations bone marrow, but this fact is questionable. Mass production of oval cells occurs with various liver lesions. For example, a significant increase in the number of oval cells was noted in patients with chronic hepatitis C, hemochromatosis, alcohol poisoning of the liver and directly correlates with the severity of liver damage. In adult rodents, oval cells are activated for subsequent reproduction when the replication of the hepatocytes themselves is blocked. The ability of oval cells to differentiate into hepatocytes and cholangiocytes (bipotential differentiation) has been shown in several studies. The ability to support the reproduction of these cells under in vitro conditions has also been shown. Recently, oval cells capable of bipotential differentiation and clonal expansion under in vitro and in vivo conditions have been isolated from the liver of adult mice. These cells expressed cytokeratin-19 and other surface markers of liver progenitor cells and, when transplanted into an immunodeficient strain of mice, induced regeneration of this organ.

Small hepatocytes were first described and isolated by Mitaka et al. from the non-parenchymal fraction of rat liver in 1995. Small hepatocytes from the liver of rats with artificial (chemically induced) liver damage or with partial removal liver (hepatectomy) can be isolated by differential centrifugation. These cells are smaller than normal hepatocytes and can proliferate and develop into mature hepatocytes under in vitro conditions. It was shown that small hepatocytes express typical markers of hepatic progenitor cells - alpha-fetoprotein and cytokeratins (CK7, CK8 and CK18), which indicates their theoretical ability for bipotential differentiation. The regenerative potential of small rat hepatocytes was tested in animal models with artificially induced liver damage: the introduction of these cells into the portal vein of animals caused the induction of repair in various parts of the liver with the appearance of mature hepatocytes.

population epithelial cells liver was first discovered in adult rats in 1984. These cells have a repertoire of surface markers that overlaps, but is still somewhat different from, the phenotype of hepatocytes and ductal cells. Transplantation of epithelial cells into the liver of rats led to the formation of hepatocytes expressing typical hepatocyte markers - albumin, alpha-1-antitrypsin, tyrosine transaminase and transferrin. Recently, this population of progenitor cells has also been found in the adult human. Epithelial cells are phenotypically distinct from oval cells and can differentiate into hepatocyte-like cells under in vitro conditions. Experiments on transplantation of epithelial cells into the liver of SCID mice (with congenital immunodeficiency) showed the ability of these cells to differentiate into albumin-expressing hepatocytes a month after transplantation.

Mesenchymal-like cells have also been obtained from mature human liver. Like mesenchymal stem cells (MSCs), these cells have a high proliferative potential. Along with mesenchymal markers (vimentin, alpha-smooth muscle actin) and stem cell markers (Thy-1, CD34), these cells express hepatocyte markers (albumin, CYP3A4, glutathione transferase, CK18) and ductal cell markers (CK19). Being transplanted into the liver of immunodeficient mice, they form mesenchymal-like functional islands of human liver tissue that produce human albumin, prealbumin, and alpha-fetoprotein.

Further studies are required on the properties, culture conditions, and specific markers of mature liver progenitor cells to assess their regenerative potential and clinical use.

Stimulants of liver regeneration

Recently discovered biologically active substances, which contribute to the regeneration of the liver in trauma and toxic damage. There are various approaches to stimulating liver regeneration in case of liver damage or massive resections. Attempts have been made to stimulate regeneration by administering amino acids, tissue hydrolysates, vitamins, hormones, growth factors such as hepatocyte growth factor (HGF), epidermal growth factor (EGF), vascular endothelial growth factor (VEGF), and a stimulant from the liver. (hepatic stimulator substance, HSS).

Stimulant from the liver

Stimulant from the liver ( hepatic stimulator substance, HSS) is an extract obtained from the liver after 30% resection. The substance known as the hepatic stimulator substance (HSS) was first described in the mid-1970s. Main active substance The ALR protein discovered in 1980–1990 ( augmenter of liver regeneration, a product of the GFER gene). In addition to ALR, tumor necrosis factor, insulin-like growth factor 1, hepatocyte growth factor, epidermal growth factor and other already known and possibly not yet identified humoral factors contained in such preparations can also affect liver regeneration. There are various methods for obtaining HSS, differing in the options for purification of extracts of the regenerating liver of animals.

Liver transplant

The world's first liver transplant was performed by American transplantologist Thomas Starles in 1963 in Dallas. Later, Starles organized in Pittsburgh (USA) the world's first transplant center, which now bears his name. By the end of the 1980s, more than 500 liver transplants per year were performed annually in Pittsburgh under the direction of T. Starzl. The first in Europe (and the second in the world) medical center for liver transplantation was established in 1967 in Cambridge (Great Britain). It was led by Roy Kaln.

As you improve surgical methods transplantation, the opening of new transplantation centers and conditions for the storage and transportation of transplanted livers, the number of liver transplants has steadily increased. If in 1997 up to 8,000 liver transplants were performed annually in the world, now this number has increased to 11,000, with over 6,000 transplants in the United States and up to 4,000 in Western European countries. Among European countries, Germany, Great Britain, France, Spain and Italy play a leading role in liver transplantation.

There are currently 106 liver transplant centers in the United States. There are 141 centers in Europe, including 27 in France, 25 in Spain, 22 each in Germany and Italy, and 7 in the UK.

Despite the fact that the world's first experimental liver transplantation was performed in the Soviet Union by the founder of world transplantology V.P. Demikhov in 1948, in clinical practice this operation was introduced in the country only in 1990. In 1990, no more than 70 liver transplantations were performed in the USSR. Now in Russia, regular liver transplant operations are performed in four medical centers, including three in Moscow (the Moscow Center for Liver Transplantation of the N.V. Sklifosovsky Research Institute for Emergency Medicine, the Academician V.I. Shumakov Research Institute of Transplantology and Artificial Organs, the Russian Scientific Center for Surgery named after Academician B. V. Petrovsky) and the Central Research Institute of Roszdrav in St. Petersburg. Recently, liver transplants have been performed in Yekaterinburg (Regional Clinical Hospital No. 1), Nizhny Novgorod, Belgorod and Samara.

Despite the constant increase in the number of liver transplants, the annual need for transplantation of this vital organ is met by an average of 50%. The frequency of liver transplants in the leading countries ranges from 7.1 to 18.2 operations per 1 million population. The true need for such operations is now estimated at 50 per 1 million population.

The first human liver transplant operations were not very successful, as the recipients usually died within the first year after the operation due to transplant rejection and the development of severe complications. The use of new surgical techniques (cavocaval shunting and others) and the emergence of a new immunosuppressant - cyclosporine A - contributed to an exponential increase in the number of liver transplants. Cyclosporine A was first successfully used in liver transplantation by T. Starzl in 1980, and its widespread clinical use was allowed in 1983. Due to various innovations, postoperative life expectancy was significantly increased. According to the UNOS - United Network for Organ Sharing, the modern survival of patients with a transplanted liver is 85-90% one year after surgery and 75-85% five years later. According to forecasts, 58% of recipients have a chance to live up to 15 years.

Liver transplant is the only radical method treatment of patients with irreversible, progressive liver damage when other alternative methods there are no treatments. The main indication for liver transplantation is the presence of chronic diffuse disease liver with a life expectancy of less than 12 months, subject to the ineffectiveness of conservative therapy and palliative surgical methods of treatment. Most common cause liver transplant is cirrhosis of the liver caused by chronic alcoholism, viral hepatitis C and autoimmune hepatitis (primary biliary cirrhosis). Less common indications for transplantation include irreversible liver damage due to viral hepatitis B and D, drug and toxic poisoning, secondary biliary cirrhosis, congenital liver fibrosis, cystic liver fibrosis, hereditary metabolic diseases (Wilson-Konovalov disease, Reye's syndrome, alpha-1 deficiency). -antitrypsin, tyrosinemia, type 1 and type 4 glycogenoses, Neumann-Pick disease, Crigler-Najjar syndrome, familial hypercholesterolemia, etc.).

A liver transplant is a very expensive medical procedure. According to UNOS, the necessary costs for hospital care and preparation of the patient for surgery, medical staff, removal and transportation of a donor liver, surgery and postoperative procedures during the first year are $314,600, and for follow-up and therapy - up to $21,900 per year . For comparison, in the United States, the cost of similar costs for a single heart transplant in 2007 was $658,800, lung - $399,000, kidney - $246,000.

Thus, the chronic shortage of donor organs available for transplantation, the length of the waiting period for surgery (in the US, the waiting time in 2006 averaged 321 days), the urgency of the operation (the donor liver must be transplanted within 12 hours), and the exceptionally high cost of traditional liver transplantation create the necessary prerequisites for the search for alternative, more cost-effective and effective strategies for liver transplantation.

Currently, the most promising method of liver transplantation is Living Donor Liver Transplantation (LDL). It is more effective, simpler, safer and much cheaper than classical cadaveric liver transplantation, both whole and split. The essence of the method is that the left lobe (2, 3, sometimes 4 segments) of the liver is removed from the donor, today often and endoscopically, that is, with little trauma. TPJD provided a very important opportunity related donation- when the donor is a relative of the recipient, which greatly simplifies both administrative problems and the selection of tissue compatibility. At the same time, thanks to a powerful regeneration system, after 4-6 months, the donor's liver completely restores its mass. The donor's liver is transplanted into the recipient either orthotopically, with the removal of one's own liver, or, more rarely, heterotopically, leaving the recipient's liver. At the same time, of course, the donor organ is practically not exposed to hypoxia, since the operations of the donor and the recipient are carried out in the same operating room and simultaneously.

Bioengineered liver

A bioengineered liver, similar in structure and properties to a natural organ, has yet to be created, but active work in this direction is already underway.

So, in October 2010, American researchers from the Institute of Regenerative Medicine at medical center Wake Forest University (Winston-Salem, North Carolina) developed a bioengineered liver organoid grown on the basis of a natural ECM bioscaffold from cultures of liver progenitor cells and human endothelial cells. The bioframework of the liver with the system of blood vessels preserved after decellularization was populated with populations of progenitor cells and endothelial cells through the portal vein. After incubation of the bioscaffold for a week in a special bioreactor with continuous circulation of the nutrient medium, the formation of liver tissue with the phenotype and metabolic characteristics of the human liver was noted. In 2013, the Russian Ministry of Defense developed terms of reference for a bioengineered liver prototype.

In March 2016, Yokohama University scientists succeeded in creating a liver that can replace a human organ. Clinical trials are expected to take place in 2019.

Liver in culture

In Homeric ideas, the liver personified the center of life in human body. In ancient Greek mythology, the immortal Prometheus was chained to the Caucasus Range for giving people fire, where a vulture (or eagle) flew in and pecked at his liver, which was restored over the next night. Many ancient peoples of the Mediterranean and the Middle East practiced divination on the liver of sheep and other animals.

Plato considers the liver to be the source of negative emotions (first of all, anger, envy and greed). In the Talmud, the liver is considered the source of malice, and the gallbladder is the source of opposition to this malice.

In Farsi, Urdu and Hindi liver (جگر or जिगर or jigar) is an image of courage or strong feelings. Expression jan e jigar(verbatim: the strength of my liver) in Urdu is one of the expressions of endearment. in Persian slang jigar can denote a beautiful person or an object of desire. In the Zulu language, the concepts of "liver" and "courage" are expressed in one word ( isibindi).

In the Gbaya language (Ubangian languages), the liver (sèè) is the source of human feelings. The expression "happiness" (dí sèè) is literally translated as "good liver", and "dissatisfaction" (dáng sèè) as "bad liver"; the verb "to envy" (ʔáá sèè) literally translates as "to place in the liver." Also, the liver in this language expresses the concept of the center.

In the Kazakh language, the liver is denoted by the word “ bauyr“. The same word (homonymous words) is often called a loved one and a close person. The appeal “bauyrym” is very common ( my native), as a rule, in relation to a person who is younger in age. Moreover, in this way they can turn not only to a relative, but also to to a stranger male. Such an address is often used when Kazakhs communicate with each other, and also to emphasize the degree of closeness (in relation to a countryman, a representative of a kind, etc.). Kazakhs have male name"Bauyrzhan" ( kindred spirit, in the Russian version they sometimes write “Baurzhan”). In particular, that was the name of the Hero Soviet Union, People's Hero of Kazakhstan ( Halyk Kaharmany) Bauyrzhan Momyshuly, Panfilov, heroic battalion commander during the Defense of Moscow in 1941.

In Russian there is an expression “to sit in the liver”, which means to disturb or annoy someone very much.

In the Lezgin language, one word is used to designate an eagle and a liver - "lek". This is due to the long-standing custom of the highlanders to expose the bodies of the dead to be eaten by predatory eagles, who first of all tried to get to the liver of the deceased. Therefore, the Lezgins believed that it was in the liver that the soul of a person was located, which now passed into the body of a bird. There is a version that the ancient Greek myth of Prometheus, whom the gods chained to a rock, and the eagle daily pecked at his liver, is an allegorical description of such a rite of burial of the highlanders.

see also

• Metabolism
• Regenerative surgery
• Regeneration

Notes

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3. Oh S.H., Witek R.P., Bae S.H., Zheng D., Jung Y., Piscaglia A.C., Petersen B.E. Bone marrow-derived hepatic oval cells differentiate into hepatocytes in 2-acetylaminofluorene/partial hepatectomy-induced liver regeneration. gastroenterology. - 2007.
4. Kanazawa Y., Verma I.M. Little evidence of bone marrow-derived hepatocytes in the replacement of injured liver. Proc Natl Acad Sci USA. - 2003.
5. Lowes K.N., Brennan B.A., Yeoh C.C, Olynyk J.K. Oval cell numbers in human chronic liver diseases are directly related to disease severity. Am J Pathol. - 1999.
6. Fougere-Deschatrette C., Imaizumi-Scherrer T., Strick-Marchand H., Morosan S., Charneau P., Kremsdorf D., Faust D.M., Weiss M.C. Plasticity of hepatic cell differentiation: bipotential adult mouse liver clonal cell lines competent to differentiate in vitro and in vivo. Stem Cells. - 2006.
7. Mitaka T., Kojima T., Mizuguchi T., Mochizuki Y. Growth and maturation of small hepatocytes isolated from adult rat liver. Biochem Biophys Res Commun. - 1995.
8. Gordon G.J., Butz G.M., Grisham J.W., Coleman W.B. Isolation, short-term culture, and transplantation of small hepatocyte-like progenitor cells from retrorsine-exposed rats. Transplantation. - 2002.
9. Ikeda S., Mitaka T., Harada K., Sugimoto S., Hirata K., Mochizuki Y. Proliferation of rat small hepatocytes after long-term cryopreservation. J Hepatol. - 2002.
10. Zhang H., Liu Z., Li R., Wang D., Liu W., Li J., Yu H., Zhang F., Dou K. Transplantation of embryonic small hepatocytes induces regeneration of injured liver in adult rat. Transplant Proc.. - 2009.
11. Zhang H., Liu Z., Li R., Wang D., Liu W., Li J., Yu H., Zhang F., Dou K. Transplantation of embryonic small hepatocytes induces regeneration of injured liver in adult rat. Transplant Proc. - 2009.
12. Tsao M.S., Smith J.D., Nelson K.G., Grisham J.W. A diploid epithelial cell line from normal adult rat liver with phenotypic properties of ‘oval’ cells. Exp Cell Res. - 1984.
13. Grisham JW, Coleman WB, Smith GJ. Isolation, culture, and transplantation of rat hepatocytic precursor (stem-like) cells. Proc Soc Exp Biol Med.. - 1993.
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“The receptacle of the soul”, “the mother of the heart”, “the source of the life principle” - as soon as the liver was not called in antiquity. Ideas about the role of this gland were rather vague, but even at the dawn of medicine, the first researchers intuitively noted the great importance that the liver has for the body. Today, scientists have a rich arsenal of knowledge about the structure, functions and role of this gland, which means they have the opportunity to develop methods for maintaining its health for many years.

Where is the human liver located and what are its functions?

The liver is the largest gland in the body. As a rule, people talk about the liver in connection with work. digestive system, however, it plays a huge role in maintaining metabolism, it neutralizes toxins. This involvement of the liver in various processes in the body explains the great attention that is usually paid to maintaining its health.

The liver is located in the abdominal cavity under the diaphragm. It is located in the region of the right hypochondrium, however, since its dimensions are quite large (the mass of a healthy liver can be up to 1800 grams), it also reaches the left hypochondrium, where it comes into contact with the stomach.

This gland consists of large lobes, and its tissue forms lobules. A lobule is a collection of hepatic cells that has the shape of a multifaceted prism. The lobules are literally entangled in a network of blood vessels and bile ducts. The lobules are separated from each other by connective tissue, which is rather poorly developed in a healthy liver. The cells of this gland are involved in the neutralization of toxins that enter the bloodstream, as well as in the production of bile and the formation of other compounds necessary for the body.

The main functions of the liver are:

• Metabolism. In the liver, proteins are broken down to amino acids, the most important compound, glycogen, is synthesized, into which excess glucose is processed, and fat metabolism also occurs (the liver is sometimes called the “fat depot”). In addition, the metabolism of vitamins and hormones is carried out in the liver.
• Detoxification. As we mentioned, various toxins and bacteria are neutralized in the liver, after which their decay products are excreted by the kidneys.
• Synthesis. This gland synthesizes bile, consisting of bile acids, pigments and cholesterol. Bile is involved in the digestion of fats, the absorption of vitamins, stimulates intestinal motility.

Reasons for the development of pathologies

Thus, normal metabolism (metabolism) in the body is impossible without the proper functioning of the liver. And that is why it is necessary to know what factors cause liver disease in order to avoid their development. The most dangerous are the following:

• Alcohol abuse
  The main metabolism of ethanol, the alcohol found in alcoholic beverages, takes place in the liver. With small volumes of alcohol consumption, liver cells have time to cope with its processing. When a reasonable dose is exceeded, ethanol contributes to damage to liver cells - the accumulation of fat in them (fatty hepatosis, or fatty degeneration), inflammation (alcoholic hepatitis) and destruction. At the same time, there is an excessive formation of connective tissue in the liver (fibrosis, and later cirrhosis and even cancer).
  A patient with alcoholic liver disease may complain of weakness, a general decrease in tone and appetite, and indigestion. Gradually, these symptoms worsen, they are joined by tachycardia, jaundice and others. At the same time, very often early stages alcoholic liver disease may not cause any pain.
• Improper nutrition
  The abundance of fatty foods and reduced physical activity lead to the fact that fat metabolism is disturbed in the body. As a result, fat begins to accumulate in the liver cells, causing their degeneration (steatosis). This leads to the fact that the active formation of free radicals begins - particles that carry an electric charge and are dangerous to cells. Foci of inflammation and necrosis appear in the liver, connective tissue grows, and cirrhosis may eventually develop.
  Improper nutrition causes diseases such as non-alcoholic fatty disease, cirrhosis, liver cancer.
• Violation of the rules for taking medicines and the effect of toxic substances
  Uncontrolled reception drugs leads to an increased load on the liver, because it processes the bulk of the drugs. It is believed that drug-induced liver damage is up to 10% of all side effects, which the drugs have on the body, and its symptoms may appear even 90 days after the end of the intake. There are other substances that are dangerous toxins for the liver, for example, industrial and vegetable poisons.
  Substances that have a toxic effect on the liver cause destruction of cell membranes, lead to malfunctions of hepatocytes (liver cells), and can cause hepatitis and liver failure. Patients complain of pain in the liver, weakness, general malaise; jaundice may develop.
• virus attack
  The impact of viruses on the liver is dangerous primarily by the development viral hepatitis. it inflammatory disease liver, which, depending on the type of virus that caused it, can even be fatal. Often the disease is asymptomatic. Sometimes patients complain of malaise, fever, pain in the right hypochondrium, jaundice. In the case of severe hepatitis, necrosis of the liver tissue may begin.

Major liver diseases

Due to the heavy load that falls on the liver, this gland is quite vulnerable: we have listed only the main negative factors that affect it, but in fact there are many more. In total, there are about 50 pathologies of this gland, and, as noted by the European Association for the Study of the Liver, about 30 million Europeans currently suffer from its chronic diseases.

Let's recap the main types. pathological changes liver:

• hepatosis (fatty liver, steatosis)
• hepatitis;
• fibrosis
• cirrhosis;
• liver failure;
• cancer and others.

Note!
According to researchers' data, about 40% of patients with liver diseases in Russia have risk factors for alcoholic damage to this organ.

Signs of malfunction of the gland and diagnosis of diseases

Violations of the liver can characterize non-specific symptoms (characteristic of other diseases), so it is not always possible to make an unambiguous conclusion that the patient is faced with a liver disease. Patients note bad feeling, loss of appetite, lethargy, stool disorders, frequent colds, increased propensity to allergic reactions, skin itching, irritability (toxins that are not neutralized in the liver have a negative effect on the brain).

Among the specific signs of violation can be identified:

• pain in the right hypochondrium;
• feeling of heaviness, discomfort in the abdomen, nausea;
• feeling of bitterness in the mouth.

The clearest sign indicating the presence of liver disease, of course, is jaundice - a change in color skin and mucous membranes. This is due to the accumulation of bilirubin in the blood.

Since the symptoms of liver disease are not always specific, if these signs appear, it is necessary to undergo an examination. Early diagnosis will help the doctor prescribe effective treatment and maximize liver function.

Pathologies are treated by a gastroenterologist. For an accurate diagnosis, he directs the patient to biochemical analysis blood to detect the level of ALT (alanine aminotransferase), LDH (lactate dehydrogenase) and AST (aspartate aminotransferase) in it. These indicators allow us to judge the presence of inflammation in the liver. By the content of other substances in the blood: GGT (gamma-glutamyl transpeptidase), bilirubin, alkaline phosphatase (alkaline phosphatase), one can judge the presence of bile stasis.

Also, the patient must pass a urine test, during which the content of bilirubin is measured.

On ultrasound of the liver, the doctor evaluates its size: in the presence of steatosis and inflammation, the gland increases, and the tissues acquire a heterogeneous structure. Modern ultrasound diagnostic technology - elastography - makes it possible to measure the so-called elasticity of liver tissues and allows you to determine the degree of fibrosis. In addition to ultrasound, magnetic resonance or computed tomography can be prescribed for diagnosis.

If the doctor needs to accurately determine the stage of the disease (for example, cirrhosis or fibrosis), a liver biopsy is performed - tissue sampling for study.

Prevention of liver diseases

One of the first steps to maintaining liver health is diet control: having a large number fatty foods, alcohol, fried and refined foods adversely affect the health of the gland. Meals should not be plentiful, it is better to eat 4-5 times a day in moderate portions.

All these measures are effective, but not always sufficient. That is why, in some cases, doctors may advise taking drugs that support liver function and help restore damaged cells.

So liver...

Ensures normal digestion

In the cells of the liver - hepatocytes - bile is formed, which is then sent to the gallbladder, and when food enters the body, it is excreted into duodenum. Bile is needed for the digestion of fats - it helps them break down and be absorbed. It also facilitates the absorption of carbohydrates and proteins. Bile also creates comfortable conditions for the work of digestive enzymes and stimulates peristalsis. small intestine, that is, it helps to ensure that the processed food moves in the right direction without problems.

Liver cells secrete bile almost non-stop - an average of 800 to 1800 ml per day (depending on the person's weight). If this production suddenly stopped, the digestion of food would become impossible.

Helps control blood glucose levels

Glucose is the main source of energy for our body. It comes from foods containing carbohydrates - sugar, pastries, cereals, berries and fruits, juices. In order for the body to work well, blood glucose levels must be at a certain level and be more or less stable. Both excess and lack of glucose are extremely harmful: against such a background, various organs can be affected - from the retina of the eye to the heart muscle.

But we don’t always control our diet exactly, so sometimes too much glucose enters the bloodstream (it’s enough to eat several sweets at once). In this case, the liver "takes" the excess, turns it into a special substance - glycogen - and stores it. If we skip meals or work hard at the gym, our blood glucose levels drop below normal. Then the liver quickly converts glycogen into glucose and feeds the body with it.

If this function did not exist, we would have diabetes, and not having time to eat on time, we would risk falling into a hypoglycemic coma.

Regulates the volume of blood in the body

Blood moves through the vessels, bringing nutrients to the organs and taking away the waste. Everyone knows this from school. But not everyone knows that the body has a so-called blood depot, which is created by reservoir organs. The liver is one of these organs, it stores a large supply of blood. For the time being, this reserve remains isolated from the main blood flow, but in case of blood loss it is quickly released into the vessels. If the liver did not perform this work, in case of accidents, injuries, after medical operations the threat to life would be much greater than now.

By the way, if there were no liver, we could even die from a small wound. It is in the liver that many blood plasma proteins are synthesized, including those that are responsible for its normal clotting, and therefore for the rapid healing of cuts and scratches.

Helps in the absorption of vitamins

Daily intake of all vitamins is a guarantee good health. If you follow a balanced diet, you can ensure the intake useful substances into the body. But this is not enough - it is necessary that the vitamins are fully absorbed. In this sense, the role of the liver can hardly be overestimated: it is directly involved in the processing of vitamins A, C, D, E, K, PP and folic acid, helping them to perform their functions. The impact of these vitamins on the body is diverse: they are needed for the full functioning of the immune system and nervous system, good vision, bone strength, normal metabolic processes, skin elasticity ...

Also, reserves of vitamins A, D and B12 are stored inside the liver, which the body uses if a new portion of useful substances has not been received for some reason. An important role is played by the body in the processing and storage of minerals - copper, cobalt and iron, which is necessary for the production of hemoglobin.

Removes all excess from the body

Our body is a huge factory. Like any production, it has its own waste - unnecessary, used, and sometimes just unnecessary components. Their removal from the body is also handled by the liver. It removes excess hormones and vitamins, as well as harmful nitrogenous compounds that are formed during metabolism.

Do not forget about the toxins that enter the body from the outside. The liver is not without reason called the main filter. Like a sponge, it passes through itself pesticides, heavy metals, preservatives, splits them into harmless substances. If this function did not exist, the body would look like a dump, and we would not live even a week, dying from poisoning.

Liver cells, hepatocytes, have a tremendous ability to regenerate. There are cases when the organ "grew" again after operations in which a person had only a quarter of it. But in order for the liver to replenish its resources, it needs favorable conditions. Alas, in modern life There are a lot of factors that can damage it, so its diseases are very common.

The peculiarity of the liver is that even if there are changes in it, it does not bother a person for a long time, pain appears only in the later stages of the disease. If you are exposed to risk factors, consult a gastroenterologist or hepatologist, undergo examinations and follow the recommendations given by your doctor.

As a rule, in the composition complex therapy liver diseases include drugs from the group of hepatoprotectors. They help the cells of the body recover faster and prevent their destruction. Some drugs from this group are also able to improve blood flow in the liver and remove excess fat from it. Such drugs can also be used for prophylactic purposes, but before taking it, you should consult your doctor.

The human organ is the liver. It is unpaired and is located on the right side of the abdominal cavity. The liver performs about 70 different functions. All of them are so important for the life of the body that even a slight disturbance in its functioning leads to serious illnesses. In addition to participating in digestion, it cleanses the blood of poisons and toxins, is a storehouse of vitamins and minerals, and performs many other 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 body

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. She got her name from the word "furnace", since this organ is very heat. The most complex chemical processes are constantly taking place there, and work is going 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 that it performs are vital for it. Therefore, this organ has regenerative abilities, that is, it can regenerate itself. But the cessation of its activities leads to the death of a person in a couple of days.

Protective function of the liver

More than 400 times a day, all blood passes through this organ, being cleansed 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. From what toxic substances does the liver cleanse the blood?

From preservatives, dyes and other additives found in foods.

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

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

From exhaust gases and heavy metals from the ambient air.

From an excess of hormones and vitamins.

From toxic products formed as a result of metabolism, such as phenol, acetone or ammonia.

Digestive function of the liver

It is in this organ that proteins, fats and carbohydrates coming from the intestines are converted into an easily digestible form. The role of the liver in the process of digestion 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 help in the digestion of food. The role of bile is especially important, 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 intestine.

The role of the liver in metabolism

Carbohydrates that come with food, only in this organ are converted into glycogen, which enters the blood in the form of glucose as needed. The process of gluconeogenesis provides the body with the right amount of glucose. The liver controls the level of insulin in the blood depending on the needs of the person.

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

serves as a storehouse 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 can be stored there, hematopoiesis processes take place in the liver. It synthesizes globulins and albumins, proteins that ensure 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 this organ the repository of?

1. This is the only place where glycogen is stored. The liver stores it and, as needed, releases it into the blood in the form of glucose.

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

3. The liver is a repository 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 liver dysfunction lead to?

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

Decreased immunity and constant colds;

Violation of blood clotting and frequent bleeding;

Severe itching, dry skin;

Hair loss, acne;

The appearance of diabetes and obesity;

Various gynecological diseases, such as early menopause;

Digestive disorders, manifested by frequent constipation, nausea and loss of appetite;

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

Disorders of water metabolism, 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 support it. It is necessary to give up alcohol, smoking, spicy and fatty foods. Limit the use of drugs, products containing preservatives and dyes.

The liver is the largest endocrine gland in the human body. She secretes her secret into the duodenum. This organ got its name from the word "furnace". This is due to the fact that this gland is the hottest organ in the human body. The liver is a whole “chemical laboratory” in which the metabolism and energy exchange takes place. To understand the basics of the functioning of this important organ, knowledge from various fields of medicine is needed: physiology, biochemistry, pathophysiology. All functions of the liver can be divided into digestive and non-digestive.

Digestive functions

The liver is involved in the processes of digestion. Its digestive functions can be divided into bile formation (choleresis) and bile excretion (cholekinesis). Bile formation occurs continuously, and bile excretion occurs only when food enters the digestive tract.

About 1.5 liters of bile is formed per day. This amount varies significantly depending on the composition of the food taken. If the food is rich in fats, extractive substances (those that give the food a spicy, spicy, peppery taste), then more bile will form. Also per day, this digestive juice is more formed in people with obesity and increased body weight. The bile formed in the liver flows through the bile ducts into the duodenum. Some of it accumulates in gallbladder, forming the so-called reserve, which is evacuated from the bladder when food is received.

The composition of bile

The composition of cystic and hepatic bile differs. The bile that is in the gallbladder is darker, more concentrated and thicker than the liver. Bile consists of water, cholesterol, bile acids, bile pigments (bilirubin and biliverdin).

Cholesterol is involved in the absorption of fats and fat-soluble vitamins.

Bile acids contribute to the emulsification of fats (break large particles of fat into microscopic balls - micelles, facilitating their digestion).

Bile pigments (bilirubin and biliverdin) are formed from hemoglobin during the destruction of red blood cells. There are indirect bilirubin (it is formed in the spleen during the destruction of old red blood cells) and direct bilirubin (it is formed in the liver from indirect). Bile pigments are processed by bacteria of the large intestine with the formation of stercobilin and urobilin. Stercobilin contributes to the brown coloration of feces, and urobilin, being absorbed from the large intestine into the blood, provides a yellow color to the urine.

Functions of bile

Bile performs the following functions:

• Emulsifies fats;
• Stimulates motility (motor activity) of the small intestine;
• Kills some microorganisms and inhibits their reproduction;
• Translates lipase (an enzyme that breaks down fats) into an active state;
• Turns pepsin (an enzyme that breaks down proteins) into an inactive state.

Non-Digestive Functions

In addition to ensuring normal digestion, the liver performs many other functions in the body. These include:

• Participation in the metabolism of carbohydrates. Three important processes occur in this organ - gluconeogenesis, gluconeogenesis and glycogenolysis. Gluconeogenesis consists in the synthesis of amino acids (components of all proteins) of glucose. Glyconeogenesis is the process of synthesis in the liver of glycogen (a storage carbohydrate in the body of all animals). Glycogen between meals undergoes glycogenolysis (breakdown) with the formation of glucose. This happens to keep normal level blood sugar at a time when it does not enter the body with food.
• Participation in protein metabolism. Most proteins in the body are synthesized in the liver. Even in this organ, the final breakdown of proteins occurs with the formation of ammonia. This fact has great importance in the pathogenesis of such a symptom of liver failure as the presence of a "liver" ammonia smell from the mouth.
• Participation in the metabolism of fats. All types of fats are synthesized in the liver: triglycerides, cholesterol, phospholipids. Triglycerides are the main component of adipose tissue and perform a storage function. Cholesterol is necessary for the formation of cell membranes, the synthesis of steroid hormones (sex hormones, mineralocorticoids, glucocorticosteroids) and calcidiol (vitamin D metabolite). Vitamin D is synthesized in the skin under the influence of ultraviolet radiation. It then goes through two stages of activation, one of which also occurs in the liver. Phospholipids are the main component of cell membranes and myelin (a fat-like substance that performs nerve fibers function of an insulator, preventing the dissipation of an electrical impulse).
• Participation in the metabolism of vitamins. The liver is responsible for the absorption and storage of fat-soluble (A, D, E, K) and some water-soluble (B6, B12) vitamins.
• Participation in the exchange of trace elements. In the described organ, the following microelements are exchanged - iron, copper, manganese, molybdenum, cobalt, zinc, etc.
• Participation in hemostasis (blood clotting). The liver synthesizes many protein factors that ensure the formation blood clot. In liver diseases, increased bleeding is often observed precisely in connection with this fact.
• Disarming function. In the liver, many toxic substances are neutralized, which are formed during the life of the body or enter it from the outside. Inactivated (neutralized) substances are then excreted from the body with bile or urine.
• "Blood depositing" function of the liver. About 30% of the blood that the heart pumps in one minute passes through the liver. When there is a shortage of blood in the body (for example, with blood loss), the blood flow is redistributed in favor of other organs, and in the liver it becomes significantly less.
• endocrine function. Everyone knows about the existence of growth hormone, which promotes the growth of the human body. However, the growth hormone itself (somatotropin) does not have such effects. It affects the liver, stimulating the formation of somatomedins (insulin-like growth factors) in it, which already independently stimulate the growth of the body. Even in the liver, calcidiol is synthesized from vitamin D, which then enters the kidneys and is converted to calcitriol, a hormone involved in the metabolism of calcium and phosphorus.
• Regulation blood pressure. Angiotensinogen is formed in the liver, which, activated in several stages, turns into angiotensin 2, a powerful factor that increases blood pressure.
• immune function. Some protective proteins (for example, antibodies, lysozyme, etc.) are formed in the liver, which have a bactericidal (kill bacteria), viricidal (kill viruses), fungicidal (kill fungi) action.
• Drug transformation. In the liver, both deactivation (neutralization) and activation of some drugs occur. That is why, in case of liver pathology, some drugs reduce their activity and require an increase in dosage, while others increase activity and involve a decrease in the dose taken in order to reduce their toxic effect on the body.
• Hematopoietic and blood-destroying function. In the described organ in an adult, the destruction of red blood cells (erythrocytes) that have served their time occurs. In the fetus, it also produces blood cells. By the time of birth, normal hematopoiesis in the liver stops, and in the newborn, this function is already performed by other organs.

Thus, the liver is a multifunctional organ that ensures the constancy of the internal environment of the body.