In patients who have sclerotherapy With the help of pharmaceuticals and the Sengstaken-Blakemore probe was not successful, you can resort to a portocaval anastomosis. Portocaval end-to-side anastomosis is very effective in stopping bleeding from esophageal varices, as it causes good decompression of the portal vein system and. partially, sinuses.

Patient A person who is indicated for emergency portocaval anastomosis must be in satisfactory condition to undergo this intervention, as it is associated with high mortality. However, as has been shown with sclerotherapy, mortality among patients in group C (according to the Child-Pugh classification) is approximately equal to mortality with portocaval anastomosis.

Portocaval shunting“side to side” is indicated for incessant bleeding from esophageal varices, combined with severe ascites and Budd-Chiari syndrome.

Portocaval anastomosis very effective in stopping acute bleeding when other methods have failed. However, this operation has two disadvantages:

1. Increased mortality if it is performed for urgent reasons.
2. Deterioration of the functional state of the liver, leading to increased encephalopathy or its provocation, if it has not yet manifested itself. This complication occurs due to the discharge of all portal blood into the systemic circulation. Several partial shunts have been proposed to reduce the incidence of hepatic encephalopathy:

N-mesocaval shunt, in which a Gore-Tech prosthesis with a diameter of 10-12 mm and a length of 4 cm is inserted between the portal and inferior vena cava. For thrombosis of the portal vein, shunting using prostheses between the superior mesenteric vein and the vena cava is indicated. This shunt is undoubtedly less effective than direct portacaval shunt, and thrombosis occurs in approximately 30% of cases. During bleeding from varices, distal splenorenal shunting cannot be performed.

Selective treatment of portal hypertension

In patients with cirrhosis of the liver Having once had bleeding, in 70% of cases there is a probability of relapse, which leads to a significant increase in mortality (up to 50-70%). For the treatment of patients with portal hypertension who have had one or more bleeding events, endoscopic sclerotherapy for esophageal varices is most appropriate. This technique gives good results with fewer complications and residual effects than bypass surgery. If sclerotherapy therapy is ineffective, a distal splenorenal anastomosis is performed according to Dean Warren. Distal splenorenal anastomosis changes the blood circulation of the esophagus, stomach and spleen in the direction of the left renal vein, keeping the portal blood flow intact. This operation is less likely to lead to the development of hepatic encephalopathy. However, it has been shown that over time, due to the development of collaterals, the results become similar to those with a portocaval anastomosis. For this reason, it is currently considered necessary to isolate the entire splenic vein up to the hilum of the spleen in order to ligate most of the afferent veins. This undoubtedly increases the duration of the operation, but slows down the appearance of collaterals.

Should not be performed surgery Warren in patients with ascites, as it tends to increase or even cause existing ascites.

Liver transplantation

Possibility of liver transplantation should only be considered in young patients with advanced cirrhosis complicated by bleeding from esophageal varices. Therefore, it is not advisable for such patients to undergo portacaval shunting or other surgical interventions on the porta hepatis: this may interfere with the transplantation, and sometimes even make it impossible. Such a patient should be assessed by a specialized surgical team with extensive experience to recommend and explore liver transplantation. There are reports of more than five-year survival of 70% of patients in group C according to the Child-Pugh classification.

The portal vein (PV, portal vein) is one of the largest vascular trunks in the human body. Without it, normal functioning of the digestive system and adequate blood detoxification are impossible. The pathology of this vessel does not go unnoticed, causing serious consequences.

The hepatic portal vein system collects blood coming from the abdominal organs. The vessel is formed by connecting the superior and inferior mesenteric and splenic veins. In some people, the inferior mesenteric vein drains into the splenic vein, and then the junction of the superior mesenteric and splenic veins forms the trunk of the PV.

Anatomical features of blood circulation in the portal vein system

The anatomy of the portal vein system (portal system) is complex. This is a kind of additional circle of venous circulation, necessary to cleanse the plasma of toxins and unnecessary metabolites, without which they would immediately fall into the inferior hollow, then into the heart and further into the pulmonary circle and the arterial part of the large one.

The latter phenomenon is observed when the liver parenchyma is damaged, for example, in patients with cirrhosis. It is the absence of an additional “filter” on the way of venous blood from the digestive system that creates the preconditions for severe intoxication with metabolic products.

Having studied the basics of anatomy at school, many remember that most organs of our body include an artery that carries blood rich in oxygen and nutritional components, and a vein emerges that carries “waste” blood to the right half of the heart and lungs.

The portal vein system is structured somewhat differently; its peculiarity can be considered the fact that in addition to the artery, the liver enters a venous vessel, the blood from which again enters the hepatic veins, passing through the parenchyma of the organ. It is as if additional blood flow is created, the work of which determines the condition of the entire organism.

The formation of the portal system occurs due to large venous trunks merging with each other near the liver. The mesenteric veins transport blood from the intestinal loops, the splenic vein leaves the spleen and receives blood from the veins of the stomach and pancreas. Behind the head of the pancreas, the venous “highways” connect, giving rise to the portal system.

Between the layers of the pancreaticoduodenal ligament, the gastric, periumbilical and prepyloric veins flow into the PV. In this area, the PV is located behind the hepatic artery and the common bile duct, together with which it follows to the porta hepatis.

At the gates of the liver, or not reaching them one to one and a half centimeters, division occurs into the right and left branches of the portal vein, which enter both hepatic lobes and there break up into smaller venous vessels. Reaching the hepatic lobule, venules entwine it from the outside, enter inside, and after the blood is neutralized upon contact with hepatocytes, it enters the central veins emerging from the center of each lobule. The central veins gather into larger ones and form hepatic veins, which carry blood from the liver and flow into.

A change in the size of the vein is of great diagnostic importance and can indicate various pathologies - cirrhosis, venous thrombosis, pathology of the spleen and pancreas, etc. The length of the portal vein of the liver is normally approximately 6-8 cm, and the diameter of the lumen is up to one and a half centimeters.

The portal vein system does not exist in isolation from other vascular systems. Nature provides the possibility of dumping “excess” blood into other veins if a hemodynamic disturbance occurs in this section. It is clear that the possibilities of such a discharge are limited and cannot last indefinitely, but they make it possible to at least partially compensate for the patient’s condition in case of severe diseases of the liver parenchyma or thrombosis of the vein itself, although sometimes they themselves become the cause of dangerous conditions (bleeding).

The connection between the portal vein and other venous collectors of the body is carried out thanks to anastomoses, the localization of which is well known to surgeons, who quite often encounter acute bleeding from anastomotic areas.

Anastomoses of the portal and vena cava are not pronounced in a healthy body, since they do not bear any load. In pathology, when the flow of blood into the liver becomes difficult, the portal vein expands, the pressure in it increases, and the blood is forced to look for other outflow routes, which become anastomoses.

These anastomoses are called portocaval, that is, the blood that should have gone to the IV goes into the vena cava through other vessels that unite both blood flow basins.

The most significant anastomoses of the portal vein include:

• Connection of gastric and esophageal veins;
• Anastomoses between the veins of the rectum;
• The junction of the veins of the anterior wall of the abdomen;
• Anastomoses between the veins of the digestive organs with the veins of the retroperitoneal space.

In the clinic, the anastomosis between the gastric and esophageal vessels is of greatest importance. If the movement of blood through the veins is disrupted, it is dilated, portal hypertension increases, then the blood rushes into the flowing vessels - the gastric veins. The latter have a system of collaterals with the esophageal, where venous blood that does not go to the liver is redirected.

Since the ability to discharge blood into the vena cava through the esophageal veins is limited, overloading them with excess volume leads to varicose veins with the likelihood of bleeding, often fatal. The longitudinally located veins of the lower and middle thirds of the esophagus do not have the ability to collapse, but are at risk of injury when eating, gag reflex, and reflux from the stomach. Bleeding from varicose veins of the esophagus and the initial part of the stomach is not uncommon in liver cirrhosis.

From the rectum, venous outflow occurs both into the venous system (upper third) and directly into the lower cavity, bypassing the liver. With an increase in pressure in the portal system, stagnation inevitably develops in the veins of the upper part of the organ, from where it is discharged through collaterals into the middle vein of the rectum. Clinically, this is expressed in varicose hemorrhoids - hemorrhoids develop.

The third junction of the two venous pools is the abdominal wall, where the veins of the peri-umbilical region take on “excess” blood and expand towards the periphery. Figuratively, this phenomenon is called the “head of Medusa” because of some external resemblance to the head of the mythical Gorgon Medusa, who had writhing snakes on her head instead of hair.

The anastomoses between the veins of the retroperitoneal space and the PV are not as pronounced as those described above, it is impossible to trace them by external signs, and they are not prone to bleeding.

Video: lecture on veins of the systemic circulation

Video: basic information about the portal vein from the notes

Pathology of the portal system

Among the pathological conditions in which the IV system is involved are:

1. Thrombosis (extra- and intrahepatic);
2. Portal hypertension syndrome (PHS) associated with liver pathology;
3. Cavernous transformation;
4. Purulent inflammatory process.

Portal vein thrombosis

Portal vein thrombosis (PVT) is a dangerous condition in which blood clots appear in the PV, preventing its movement towards the liver. This pathology is accompanied by an increase in pressure in the vessels - portal hypertension.

4 stages of portal vein thrombosis

According to statistics, among residents of developing regions, LPG is accompanied by thrombus formation in the veins in a third of cases. In more than half of patients who die from cirrhosis, thrombotic clots can be detected postmortem.

The causes of thrombosis are considered:

• Cirrhosis of the liver;
• Malignant intestinal tumors;
• Inflammation of the umbilical vein during catheterization in infants;
• Inflammatory processes in the digestive organs - cholecystitis, pancreatitis, intestinal ulcers, colitis, etc.;
• Injuries; surgical interventions (bypass surgery, removal of the spleen, gallbladder, liver transplant);
• Blood clotting disorders, including certain neoplasias (polycythemia, pancreatic cancer);
• Some infections (tuberculosis of portal lymph nodes, cytomegalovirus inflammation).

Among the very rare causes of PVT include pregnancy and long-term use of oral contraceptives, especially if the woman has crossed the age of 35-40.

Symptoms of PVT consists of severe abdominal pain, nausea, dyspeptic disorders, vomiting. Possible increase in body temperature, bleeding from hemorrhoids.

Chronic progressive thrombosis, when blood circulation through the vessel is partially preserved, will be accompanied by an increase in the typical picture of LPG - fluid will accumulate in the abdomen, the spleen will enlarge, giving characteristic heaviness or pain in the left hypochondrium, and the veins of the esophagus will dilate with a high risk of dangerous bleeding.

The main way to diagnose PVT is ultrasound, and a thrombus in the portal vein looks like a dense (hyperechoic) formation that fills both the lumen of the vein itself and its branches. If ultrasound is supplemented with Doppler ultrasound, then there will be no blood flow in the affected area. Cavernous degeneration of blood vessels due to dilation of small-caliber veins is also considered characteristic.

Small thrombi of the portal system can be detected by endoscopic ultrasound, and CT and MRI make it possible to determine the exact causes and look for possible complications of thrombus formation.

Video: incomplete portal vein thrombosis on ultrasound

Portal hypertension syndrome

Currently answering questions: A. Olesya Valerievna, Ph.D., teacher at a medical university

Structure of the liver, size of the liver, segments of the liver. Vascular system of the liver. Arterial blood supply. Portal vein. Biliary system. Ultrastructure of the liver.

Anatomy of the liver

Liver- one of the largest organs of the human body, playing an important role in digestion and metabolism. It is difficult to name another organ with as wide a variety of functions as the liver.

The relative size and weight of the liver are subject to significant fluctuations depending on age. The weight of the liver of an adult is 1300 - 1800. The liver of newborns and children in the first month of life occupies 1/2 or 1/3 of the abdominal cavity, averaging 1/18 of the body weight, and in adults it is only 1/36 of the body weight. However, already in three-year-old children, the liver has the same relationship with the abdominal organs as in adults, although its edge protrudes more from under the costal arch due to the child’s short chest.

The liver is covered by peritoneum on all sides, with the exception of the gate and part of the posterior surface. The parenchyma of the organ is covered with a thin, durable fibrous membrane (Glisson's capsule), which enters the parenchyma of the organ and branches in it.

Skeletotopy of the liver

The liver is located directly below the diaphragm in the upper right abdominal cavity, a small part of the organ in an adult extends to the left of the midline. The organ has stable landmarks in relation to the skeleton, which are used to determine its boundaries (Fig. 1). The upper border of the liver on the right with maximum exhalation is located at the level of the 4th intercostal space along the right nipple line, the upper point of the left lobe reaches the 5th intercostal space along the left parasternal line. The upper edge of the liver has a slightly oblique direction, running along a line from the fourth right rib to the cartilage of the fifth left rib. The anterior inferior edge of the liver on the right along the axillary line is at the level of the 10th intercostal space, its projection coincides with the edge of the costal arch along the right nipple line. Here the anterior edge departs from the costal arch and stretches obliquely to the left and upward; along the midline it is projected in the middle of the distance between the navel and the base of the xiphoid process. Next, the anterior edge of the liver crosses the left costal arch and at the level of the VI costal cartilage along the left parasternal line passes into the upper edge.

Determination of the projection of the anterior edge of the liver very important when performing percutaneous needle biopsy of the liver. The anterior projection of the liver has the appearance of an almost right-angled triangle, mostly covered by the chest wall, only in the epigastric region the lower edge of the liver extends beyond the costal arches and is covered by the anterior abdominal wall. The posterior projection of the liver occupies a relatively narrow strip. The upper edge of the liver is projected at the level of the lower edge of the IX thoracic vertebra, and the lower border runs along the middle of the XI thoracic vertebra.

The location of the liver changes depending on the position of the body. In a vertical position, the liver lowers slightly, and in a horizontal position it rises. The displacement of the liver during breathing is used during its palpation: in most cases, it is possible to determine its lower edge during the deep inspiration phase.

Rice. 1

It is important to remember the variations in the position of the liver in relation to the sagittal plane of the body; distinguish between the right-sided and left-sided position of the liver. In the right-sided position, the liver lies almost vertically and has a highly developed right lobe and a reduced left one. In some cases, the entire organ does not cross the midline, being located in the right half of the abdominal cavity. In a left-sided position, the organ lies in a horizontal plane and has a well-developed left lobe, sometimes even extending beyond the spleen. These variations in the position of the liver must be taken into account when assessing the results of scanning and echolocation of the organ.

Segmental division of the liver

According to external signs, the liver is divided into right and left lobes of unequal size. On the upper convex surface, the border between the lobes is the place of attachment of the falciform ligament; on the lower surface, the border is the left and right longitudinal grooves. In addition, the quadrate and caudal lobes are distinguished, which were previously classified as the right lobe. The quadrate lobe is located between the anterior sections of two longitudinal grooves. The caudal lobe of the liver is located between the posterior sections of the longitudinal grooves. The gallbladder is located in the anterior part of the recess on the lower surface of the right lobe of the liver. In the deep transverse groove on the lower surface of the right lobe there is the gate of the liver. Through the gate, the hepatic artery and portal vein with their accompanying nerves enter the liver, and the common hepatic bile duct and lymphatic vessels exit.

The basis of modern anatomical and functional division is the doctrine of the segmental structure of the liver. Lobes, sectors, segments are usually called areas of the liver of various sizes that have separate blood and lymph circulation, innervation and outflow of bile. The portal vein, hepatic artery, bile ducts and hepatic veins branch in the liver. The course of the branches of the portal vein, hepatic artery and bile duct within the organ is relatively identical. These vessels and bile ducts are usually called the Glissonian, or portal, system, in contrast to the hepatic veins, which are called the caval system. Segmental division of the liver is carried out along the portal and caval systems. Division of the liver according to the portal system is more often used in surgical practice, as it has more anatomical justifications.

The intrahepatic architecture of the portal vein underlies most segmental division patterns (Fig. 2). The classification of S. Couinaud (1957) has become widespread, according to which the liver is divided into 2 lobes - right and left, 5 sectors and 8 most constantly occurring segments. The segments, grouped along radii around the gate of the liver, are included in larger independent sections of the organ, called sectors. Thus, segments III and IV form the left paramedian sector. The left lateral sector (monosegmental includes only segment II, and the right paramedian sector includes segments V and VIII, the right lateral sector includes segments VI and VII; segment I is the dorsal sector (monosegmental). Each lobe, sector or segment of the liver has in most cases, the so-called Glissonian pedicle, accessible to surgical treatment, in which, closely adjacent to each other, are located the branches of the portal vein, hepatic artery and hepatic duct, covered with a connective tissue membrane.

Blood vessels

Blood enters the liver from the portal vein and hepatic artery; 2/3 of the blood volume enters through the portal vein and only 1/3 through the hepatic artery. However, the importance of the hepatic artery for the functioning of the liver is great, since arterial blood is rich in oxygen.

Arterial blood supply to the liver carried out from the common hepatic artery (a. hepatica communis), which is a branch of the truncus coeliacus. Its length is 3 - 4 cm, diameter 0.5 - 0.8 cm. The hepatic artery directly above the pylorus, not reaching 1-2 cm from the common bile duct, is divided into a. gastroduodenalis and a. hepatica propria. The proper hepatic artery (a. hepatica propria) passes upward in the hepatoduodenal ligament, while it is located to the left and somewhat deeper than the common bile duct and in front of the portal vein. Its length ranges from 0.5 to 3 cm, diameter from 0.3 to 0.6 cm. The proper hepatic artery in its initial section gives off a branch - the right gastric artery and, before entering the gate of the liver or directly at the gate, is divided into the right and left branch. In some cases, a branch arises from the hepatic artery - the quadrate lobe of the liver. Typically, the left hepatic artery supplies the left, quadrate, and caudal lobes of the liver.

Right hepatic artery supplies mainly the right lobe of the liver and gives an artery to the gallbladder.

Arterial anastomoses of the liver are divided into two systems: extraorgan and intraorgan. The extraorgan system is formed mainly by branches extending from a. hepatica communis, aa. gastroduodenalis and hepatica dextra. The intraorgan collateral system is formed through anastomoses between the branches of the liver's own artery.

Venous system of the liver represented by afferent and efferent veins. The main afferent vein is the portal vein. The outflow of blood from the liver occurs through the hepatic veins, which flow into the inferior vena cava.

Portal vein(vena portae) is most often formed from two large trunks: the splenic vein (v. lienalis) and the superior mesenteric vein (v. mesenterica superior).

Rice. 2. Scheme of segmental division of the liver: A - diaphragmatic surface; B - visceral surface; B - segmental branches of the portal vein (projection on the visceral surface). I - VIII - liver segments, 1 - right lobe; 2 - left lobe.

The largest tributaries are the gastric veins (v. gastrica sinistra, v. gastrica dextra, v. prepylorica) and the inferior mesenteric vein (v. mesenterica inferior) (Fig. 3). The portal vein most often begins at the level of the second lumbar vertebra behind the head of the pancreas. In some cases, it is located partially or completely within the parenchyma of the gland, has a length of 6 to 8 cm, a diameter of up to 1.2 cm, and has no valves. At the level of the portal of the liver v. portae is divided into the right branch, which supplies the right lobe of the liver, and the left branch, which supplies the left, caudal and quadrate lobes.

Portal vein connected by numerous anastomoses with the vena cava (portocaval anastomosis). These are anastomoses with the veins of the esophagus and the veins of the stomach, rectum, periumbilical veins and veins of the anterior abdominal wall, as well as anastomoses between the roots of the veins of the portal system (superior and inferior mesenteric, splenic, etc.) and the veins of the retroperitoneal space (renal, adrenal, testicular veins or ovary, etc.). Anastomoses play an important role in the development of collateral circulation in case of outflow disorders in the portal vein system.

Portocaval anastomoses are especially well expressed in the rectal area, where the v. rectalis superior, flowing into v. mesenterica inferior, and vv. rectalis media et inferior, related to the inferior vena cava system. On the anterior abdominal wall there is a pronounced connection between the portal and caval systems through vv. paraumbilicales. In the area of ​​the esophagus through connections v. gastrica sinistra and v.v. oesophagea an anastomosis of the portal vein with v. is created. azygos, i.e., the system of the superior vena cava (Fig. 4).

Hepatic veins(v.v.hepaticae) are the efferent vascular system of the liver. In most cases there are three veins; right, middle and left, but their number can greatly increase, reaching 25. The hepatic veins drain into the inferior vena cava below where it passes through the opening in the tendinous part of the diaphragm into the chest cavity.

Rice. 3. Portal vein and its large branches (according to L. Schiff). P - portal vein; C - gastric vein; IM - inferior mesenteric vein; S - splenic vein; SM - superior mesenteric vein.

In most cases, the inferior vena cava passes through the posterior part of the liver and is surrounded by parenchyma on all sides.

Portal hemodynamics characterized by a gradual drop from high pressure in the mesenteric arteries to the lowest level in the hepatic veins. It is important that the blood passes through two capillary systems: the capillaries of the abdominal organs and the sinusoidal bed of the liver. Both capillary networks are connected to each other by the portal vein.

Blood of the mesenteric arteries under a pressure of 120 mm Hg. Art. enters the network of capillaries of the intestines, stomach, and pancreas. The pressure in the capillaries of this network is 15 - 10 mm Hg. Art. From this network, blood enters the venules and veins that form the portal vein, where normally the pressure does not exceed 10 - 5 mm Hg. Art. From the portal vein, blood is directed into the interlobular capillaries, from there it enters the hepatic venous system and passes into the inferior vena cava. The pressure in the hepatic veins ranges from 5 mm Hg. Art. to zero.

Thus, the pressure drop in the portal bed is 120 mmHg. Art. Blood flow may increase or decrease with changes in pressure gradient. G. S. Magnitsky (1976) emphasizes that portal blood flow depends not only on the pressure gradient, but also on the hydromechanical resistance of the portal vessels, the value of which is determined by the total resistance of the first and second capillary systems. A change in resistance at the level of at least one capillary system leads to a change in the total resistance and an increase or decrease in portal blood flow. It is important to emphasize that the pressure drop in the first capillary network is 110 mmHg. Art., and in the second - only 10 mm Hg. Art. Consequently, the main role in changing portal blood flow is played by the capillary system of the abdominal organs, which is a powerful physiological tap. Significant fluctuations in hydromechanical resistance occur as a result of changes in the lumen of blood vessels under the influence of nervous and humoral regulation. Through the portal bed in humans, blood flows at an average speed of 1.5 l/min, which corresponds to 1/3 of the IOC.

Liver histotopography

Liver It is a mass of liver cells penetrated by blood sinusoids. According to modern concepts, hepatocytes form anastomosing plates from one row of cells that are in close contact with the branched blood labyrinth of the sinusoids (Fig. 5). Since 1883, the main morphophysiological unit of the liver has been considered a “classical” hexagonal lobule; its center is the hepatic vein - the initial link of the venous system that collects blood flowing from the liver. The parenchyma of the lobules is formed by radially located hepatic beams; these are plate-like formations one cell thick. The lobules are separated from each other by layers of connective tissue called portal fields associated with the fibrous capsule of the liver.

Rice. 4. Portocaval anastomoses (according to B V Petrovsky): 1 - portocaval anastomoses in the rectal area 2 - anastomoses in the esophagus. 3 - anastomoses in the stomach, IVC - inferior vena cava. PV - portal vein

The interlobular connective tissue of a normal liver is poorly developed. The portal fields contain branches of the portal vein, hepatic artery, bile and lymphatic canaliculi. Penetrating through the terminal plate of hepatocytes, which separates the parenchyma of the lobules from the portal field, the portal vein and hepatic artery give their blood to the sinusoids. The sinusoids drain into the central vein of the lobule. The diameter of the sinusoids ranges from 4 to 25 microns, depending on the functional state of the liver. At the point where the venule flows into the sinusoid and the sinusoid into the hepatic vein, there are external and internal smooth muscle sphincters that regulate blood flow into the lobule. The hepatic arteries, like the corresponding veins, break up into capillaries. They enter the liver lobule and, at its periphery, merge with capillaries originating from the portal veins. Due to this, blood coming from the portal vein and the hepatic artery mixes in the intralobular capillary network (Fig. 6).

Rice. 5. Reconstruction of a liver fragment according to N. Elias

There is another point of view, according to which the secretory lobule or an acinar unit similar to it is taken as a morphophysiological unit. The liver parenchyma is functionally divided into small areas with a portal field in the center, limited by the central veins of two adjacent hepatic lobules, 3-4 such fragments of parenchyma form a complex acinus or portal lobule with a vascular bundle of the portal tract in the center and hepatic veins lying in three corners on the periphery .

Intralobular sinusoids, representing the microvasculature of the circulatory system of the liver, are in direct contact with each hepatocyte. The unique structure of the walls of the hepatic sinusoids contributes to the maximum exchange between the bloodstream and the hepatic parenchyma. The wall of the liver sinusoids does not have the basement membrane characteristic of the capillaries of other organs and is built from a single row of endothelial cells. Between the endothelial cells and the surface of the liver cells there is a free perisinusoidal space - the space of Disse. It has been established that the surface of endothelial cells is covered with a substance of mucopolysaccharide nature, which also fills the cellular pores of Kupffer cells, intercellular gaps and spaces of the DNA. This substance carries out intermediary exchange between blood and liver cells. The functionally active surface of liver cells increases significantly due to numerous tiny outgrowths of the cytoplasm - microvilli.

Rice. 6. 1 - portal vein; 2 - hepatic artery; 3 - sinusoids; 4 - internal sphincter; 5 - central vein; 6 - external sphincter; 7 - arteriole.

Endothelial cells, depending on their functional state, are divided into endothelial cells themselves, which perform a support function, active endothelial cells (Kupffer cells), which have a phagocytic function, and fibroplastic cells, which participate in the formation of connective tissue. Histochemical examination in the cytoplasm of Kupffer cells reveals an increased content of RNA, PAS-positive granules, and high activity of acid phosphatase.

The connective tissue of the portal fields, along with the portal triad, including branches of the portal vein, hepatic artery and interlobular bile ducts, contains single lymphocytes, histiocytes, plasma cells and fibroblasts. The connective tissue of the portal tracts is represented by collagen fibers, clearly visible when stained with picrofuchsin or the three-color Mallory method.

Biliary system

Its initial link is the intercellular bile canaliculi (capillaries), formed by the biliary poles of two or more adjacent hepatocytes (Fig. 7). Bile canaliculi do not have their own wall; they are formed by the cytoplasmic membranes of hepatocytes. Histological examination does not reveal bile canaliculi, but is clearly visible in the reaction to alkaline phosphatase. Intercellular bile canaliculi, merging with each other at the periphery of the hepatic lobule, form larger perilobular bile ducts (terminal ductules, cholangioles). Cholangioles are formed by cuboidal epithelial cells. During electron microscopic examination, microvilli are visible on the surface of the epithelial cells of the cholangioles. Passing through the terminal plate of hepatocytes, in the periportal zone the cholangioles flow into the interlobular bile ducts (ducts, cholangae). The walls of these ducts are formed by connective tissue; in larger ducts there is also a layer of smooth muscle fibers.

Rice. 7. Intrahepatic biliary tract (according to N. Popper, F. Schaffner). 1 - liver cell; 2 - Kupffer cell; 3 - sinusoid; 4 - intercellular bile canaliculus; 5 - perilobular bile duct; b - interlobular bile duct; 7 - vein; 8 - lymphatic vessel.

Rice. 8. Extrahepatic bile ducts. 1 - gallbladder; 2- - ductus cysticus; 3 - ductus hepaticus; 4 - ductus choledochus; 5 - ductus pancreaticus; 6 - sphincter Oddi.

On the lower surface of the liver, in the region of the transverse groove, the left and right bile ducts join to form the common hepatic duct. The latter, merging with the cystic duct, flows into the common bile duct 8–12 cm long. The common bile duct opens into the lumen of the duodenum in the area of ​​the major duodenal papilla. The distal end of the common bile duct is dilated, in its wall there is a layer of smooth muscle - the sphincter (Fig. 8),

Ultrastructure of a hepatocyte

Upon electron microscopic examination, the hepatocyte has an irregular hexagonal shape with unclearly defined angles.

There is a sinusoidal pole facing the blood sinusoid and a biliary pole facing the bile canaliculus (Fig. 9). The cytoplasmic membrane of the hepatocyte consists of outer and inner layers, between them there is an osmiophobic layer 2.5 - 3.0 nm wide. The membrane has pores that provide communication between the endoplasmic reticulum and the extracellular environment. Numerous membrane outgrowths - microvilli - are especially clearly expressed at the sinusoidal pole of the hepatocyte; they increase the functionally active area of ​​the hepatocyte. Numerous metabolites are captured by the villi of the sinusoidal pole, and secretion is carried out at the biliary pole of the hepatocyte. These processes are regulated by enzyme systems, in particular alkaline phosphatase and ATPase. Hyaloplasm, the main substance of the cytoplasm of hepatocytes, is weakly osmiophilic, with vaguely defined small granules, vesicles and fibrils. Soluble components of the cytoplasmic matrix include a significant amount of protein, a small amount of RNA and lipids, enzymes of glycolysis, transamination, etc. The hyaloplasm contains cytoplasmic organelles and inclusions. Core. Round and light, it is located in the central part of the hepatocyte, has a clearly visible nuclear envelope, a few small clumps of chromatin and from 1 to 4 round oxyphilic nucleoli. In rare cases, hepatocytes contain two nuclei.

The nuclear envelope in hepatocytes is closely connected with the endoplasmic reticulum: direct transitions of the outer membrane of the nuclear envelope into the membranes of the endoplasmic reticulum and communication of the slit-like space between the membranes of the nuclear envelope with the tubules of the granular endoplasmic reticulum are observed. DNA and histones in the form of a deoxyribonucleoprotein complex, acidic proteins, rRNA, and mRNA are localized in the chromatin of the nucleus. Numerous enzymes involved in the synthesis of RNA, DNA and protein are found in the hepatocyte nucleus.

The endoplasmic reticulum of the hepatocyte is represented by a system of tubules and cisterns formed by parallel membranes. The endoplasmic reticulum consists of two parts: granular (granular) and smooth. Under physiological conditions, the granular part is much more developed than the smooth part; it is located mainly around the nucleus and mitochondria; on its outer membrane there are numerous osmiophilic granules with a diameter of 12 - 15 nm - ribosomes. The membranes of the smooth endoplasmic reticulum are located near the biliary pole of the hepatocyte, where the synthesis of glyco- and lipoproteins, glycogen, and cholesterol occurs. Both parts of the endoplasmic reticulum are closely interconnected, representing a system of continuous tubes. The physiological role of the endoplasmic reticulum is the neutralization of medicinal and toxic substances, conjugation of bilirubin, metabolism of steroids, biosynthesis of proteins secreted by the cell into the tissue fluid, and direct participation in carbohydrate metabolism.

Rice. 9. Scheme of the ultrastructure of a hepatocyte (I), Kupffer cell (II), bile-epithelial cell (III) (according to A.F. Blyuger). 1 - core; 2 - nucleolus; 3 - nuclear membrane; 4 - rough endoplasmic reticulum; 5 - smooth endoplasmic reticulum; 6 - mitochondria; 7 - Golgi complex; 8 - lysosomes; 9 - polyribosomes; 10 - ribosomes; II - microtubule; 12 - desmosome; 13 - vacuole; 14 - space of Disse; 15 - bile canaliculus; 16 - peroxisome; 17 - pinocytotic vesicles; 18 - sinusoids", 19 - lipids; 20 - basement membrane: 21 - microvilli; 22 - glycogen; 23 - interlobular bile duct; 24 - centriole.

Golgi apparatus, or lamellar complex, consists of double membranes forming flattened sacs and small vesicles. It is usually located in close proximity to the smooth endoplasmic reticulum at the biliary pole of the hepatocyte. The functional purpose of the Golgi apparatus is determined by its important role in secretory processes. Depending on the phase of bile secretion, the components of the Golgi apparatus change. Its participation in the formation of lysosomes and glycogen is assumed.

In the cytoplasm of hepatocytes, in close topographic contact with the tubular system described above, there are granular formations: mitochondria, lysosomes, microbodies.

Mitochondria have very variable shape and location in the cell depending on its location in the lobule or the characteristics of the functional state. Typically, mitochondria are round, oval or elongated, surrounded by a three-layer membrane. The inner layer of membranes forms membrane partitions - cristae, on which granular particles are located. Oxidative phosphorylation occurs in granular particles. The mitochondrial matrix has a fine-grained structure, containing RNA granules, thin strands of DNA and single lipid inclusions. The most important enzyme systems are localized in mitochondria; the central place among them is occupied by the enzymes of the Krebs cycle, deamination and transamination enzymes.

Lysosomes They have a round or ellipsoidal shape, surrounded by a single-layer lipoprotein membrane. Lysosomes are usually localized at the biliary pole of the hepatocyte, and therefore they are called peribiliary bodies. The greatest number of lysosomes are contained in the peripheral zones of the hepatic lobule. Lysosomes are considered as an apparatus for intracellular digestion and are divided into primary, which have not yet used their lytic enzymes, and secondary, in which contact between hydrolases and the substrate has already occurred. Secondary lysosomes are divided into digestive vacuoles, which carry out the lysis of exogenous substances that enter the cell through pinocytosis and phagocytosis, autophagy vacuoles, which carry out the lysis of endogenous material, and residual bodies, or segrosomes, containing compact material in which the breakdown of the substrate is completed. The function of lysosomes can be defined as “intracellular digestion”; they participate in protective reactions, the formation of bile, and ensure intracellular homeostasis. In addition to organelles, the cytoplasm of hepatocytes contains various inclusions: glycogen, lipids, pigments, lipofuscins.

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The convex diaphragmatic surface of the liver (facies diaphragmatica) faces upward and posteriorly. Anteriorly and especially to the left, the liver becomes thinner (Fig. 1 and 2). The lower visceral surface (facies visceralis) is concave. The liver occupies the right hypochondrium and extends through the epigastric region into the left hypochondrium. The anterior pointed edge of the liver usually does not extend from under the right costal arch to the outer edge of the right rectus abdominis muscle. Next, the lower border of the liver passes obliquely to the junction of the cartilages of the VII and VIII left ribs. The liver occupies almost the entire dome of the diaphragm. On the left it comes into contact with the stomach, below - with the right kidney, with the transverse colon and duodenum.

Rice. 2. Liver (top): 1 - lis. triangulare deist.; 2 - diaphragm; 3 - lig. coronarium hepatis; 4 - lig. triangulare sin.; 5 - appendix fibrosa hepatis; 6 - lobus sin. hepatis; 7 - lig. falciforme hepatis; 8 - lig. teres hepatis; 9 - incisura lig. teretis; 10 - margo inf.; 11 - vesica fellea (fundus); 12 - lobus dext. hepatis.

Rice. 3. Liver (back): 1 - lig. triangulare sin.; 2 - impressio gastrica; 3 - lig. coronarium hepatis; 4 - impressio oesophagea; 5 - lig. venosum hepatis; 6 - lobus caudatus hepatis; 7 - lig. falciforme hepatis; 8 - v. hepatica; 9 - lobus dext. hepatis; 10 - v. cava inf.; 11 - lig. v. cavae; 12 - facies diaphragmatica; 13 - impressio suprarenalis; 14 - processus caudatus; 13 - collum vesicae felleae; 16 - lig. triangulare dext.; 17 - impressio renalis; 18 - impressio colica; 19 - impressio duodenalis; 20 - vesica fellea; 21 - ductus choledochus; 22 - v. portae; 23 - lobus quadratus; 24 - lig. falciforme hepatis; 26 - a. hepatica propria; 26 - lig. teres hepatis; 27 - porta hepatis; 28 - tuber omentale; 29 - lobus sin.; 30 - appendix fibrosa hepatis.

The liver, with the exception of the upper-posterior surface attached to the diaphragm, is covered with peritoneum. The transition of the peritoneum from the diaphragm to the liver along the frontal plane is designated as the coronary ligament (lig. coronarium hepatis), the transition along the sagittal plane is designated as the falciform ligament (lig. falciforme hepatis), dividing the diaphragmatic surface of the liver into the right and left lobes (lobus hepatis dexter et sinister ). The visceral surface is divided into right, left, caudate (lobus caudatus) and square (lobus quadratus) lobes by two longitudinal grooves and one transverse one (porta of the liver). The gallbladder (see) is placed in the recess of the right longitudinal groove in front, and the inferior vena cava in the back. The left longitudinal groove includes the round ligament of the liver (lig. teres hepatis), formed from the neglected umbilical vein. Here it passes into the venous ligament (lig. venosum) - the remnant of the overgrown ductus venosus. Under the peritoneum on top of the liver there is a connective tissue capsule.

The portal vein (see) and the hepatic artery entering the gate of the liver and the lymphatic vessels and bile duct exiting the gate (Fig. 3) are covered with layers of peritoneum that make up the hepatoduodenal ligament (lig. hepatoduodenal). Its continuation is the hepatogastric ligament (lig. hepatogastricum) - the lesser omentum. A sheet of peritoneum stretches down to the right kidney from the liver - the hepatorenal ligament (lig. hepatorenale). Between the liver and the diaphragm on the sides of the falciform ligament, the right and left hepatic bursae (bursa hepatica dext. et sin.) are distinguished; between the liver and the stomach behind the lesser omentum is the omental bursa (bursa omentalis). Liver segments are shown in Fig.

The main segments of the liver: I - anterior segment: II - posterior segment; III - medial segment; IV - lateral segment. 1 - ductus cholcdoclius; 2 - v. portae; 3 - a. hepatica.

The bloodstream of the liver consists of the intraorgan part of the venous portal system, the drainage system of the hepatic veins and the system of hepatic arteries. Arterial blood supply to the liver is carried out by the hepatic artery (from the celiac artery system), which, entering the portal of the liver, is divided into right and left branches. Often there are accessory hepatic arteries coming from the branches of the celiac artery and from the superior mesenteric artery. The portal vein brings the bulk of blood to the liver. It is divided into lobar veins, from which segmental veins originate. Continuing to divide, the branches of the portal vein first become interlobular, and then thin septal venules, turning into capillaries - sinusoids of the lobule. The septal arterioles also open here, completing the branching of the segmental intrahepatic arteries. Thus, mixed blood flows through the sinusoids. Sinusoids are equipped with devices to regulate blood flow. As a result of the fusion of sinusoids, the central veins of the lobules are formed, from which blood flows first into the sublobular, and then into the collecting veins and, finally, into 3-4 hepatic veins. The latter open into the inferior vena cava. The lymphatic system of the liver (Fig. 4) begins with perilobular and superficial networks of capillaries, folding into superficial and deep lymphatic vessels, through which lymph flows either to the lymph nodes at the porta hepatis, or to the subphrenic nodes around the inferior vena cava. The vagus nerves and branches of the solar plexus take part in the innervation of the liver, thanks to which autonomic and afferent innervation is provided.

Blood supply to the liver

The blood supply to the liver is carried out by a system of arteries and veins, which are connected to each other and to the vessels of other organs. This organ performs a huge number of functions, including the detoxification of toxins, the synthesis of proteins and bile, and the storage of many compounds. Under conditions of normal blood circulation, it does its job, which has a positive effect on the condition of the whole organism.

How do blood circulation processes occur in the liver?

The liver is a parenchymal organ, that is, it does not have a cavity. Its structural unit is a lobule, which is formed by specific cells, or hepatocytes. The lobule has the shape of a prism, and neighboring lobules are combined into lobes of the liver. The blood supply to each structural unit is carried out using the hepatic triad, which consists of three structures:

Main arteries of the liver

Arterial blood enters the liver from vessels that originate from the abdominal aorta. The main artery of the organ is the hepatic one. Along its length, it gives blood to the stomach and gall bladder, and before entering the gate of the liver or directly in this area, it is divided into 2 branches:

• the left hepatic artery, which carries blood to the left, quadrate and caudal lobes of the organ;
• the right hepatic artery, which supplies blood to the right lobe of the organ and also gives off a branch to the gallbladder.

The arterial system of the liver has collaterals, that is, areas where neighboring vessels are united through collaterals. These may be extrahepatic or intraorgan associations.

Large and small veins and arteries take part in the blood circulation of the liver

Veins of the liver

The veins of the liver are usually divided into afferent and efferent. Along the afferent tract, blood moves to the organ, and along the efferent tract, it moves away from it and carries away the final products of metabolism. Several main vessels are associated with this organ:

• portal vein - an afferent vessel that is formed from the splenic and superior mesenteric veins;
• hepatic veins are a system of drainage tracts.

The portal vein carries blood from the organs of the digestive tract (stomach, intestines, spleen and pancreas). It is saturated with toxic metabolic products, and their neutralization occurs in the liver cells. After these processes, the blood leaves the organ through the hepatic veins, and then participates in the systemic circulation.

Diagram of blood circulation in the liver lobules

The topography of the liver is represented by small lobules, which are surrounded by a network of small vessels. They have structural features that help cleanse the blood of toxic substances. When entering the portal of the liver, the main afferent vessels are divided into small branches:

• equity,
• segmental,
• interlobular,
• intralobular capillaries.

These vessels have a very thin muscle layer to facilitate blood filtration. At the very center of each lobule, the capillaries merge into a central vein, which is devoid of muscle tissue. It flows into the interlobular vessels, and they, accordingly, into the segmental and lobar collecting vessels. Leaving the organ, the blood is distributed through 3 or 4 hepatic veins. These structures already have a full muscle layer and carry blood into the inferior vena cava, from where it enters the right atrium.

Portal vein anastomoses

The blood supply to the liver is adapted to ensure that the blood from the digestive tract is cleared of metabolic products, poisons and toxins. For this reason, stagnation of venous blood is dangerous for the body - if it collects in the lumen of blood vessels, toxic substances will poison the person.

Anastomoses are bypass routes for venous blood. The portal vein is connected to the vessels of some organs:

If for some reason the fluid cannot enter the liver (due to thrombosis or inflammatory diseases of the hepatobiliary tract), it does not accumulate in the vessels, but continues to move along bypass routes. However, this condition is also dangerous because the blood does not have the opportunity to get rid of toxins and flows into the heart in an unclean form. Portal vein anastomoses begin to function fully only in pathological conditions. For example, with cirrhosis of the liver, one of the symptoms is the filling of the veins of the anterior abdominal wall near the navel.

The most important processes occur at the level of liver lobules and hepatocytes

Regulation of blood circulation processes in the liver

The movement of fluid through the vessels occurs due to the pressure difference. The liver constantly contains at least 1.5 liters of blood, which moves through large and small arteries and veins. The essence of blood circulation regulation is to maintain a constant amount of fluid and ensure its flow through the vessels.

Mechanisms of myogenic regulation

Myogenic (muscular) regulation is possible due to the presence of valves in the muscular wall of blood vessels. When muscles contract, the lumen of the blood vessels narrows and fluid pressure increases. When they relax, the opposite effect occurs. This mechanism plays a major role in the regulation of blood circulation and is used to maintain constant pressure in different conditions: during rest and physical activity, in heat and cold, with increases and decreases in atmospheric pressure and in other situations.

Humoral regulation

Humoral regulation is the effect of hormones on the condition of the walls of blood vessels. Some of the biological fluids can affect veins and arteries, expanding or narrowing their lumen:

• adrenaline - binds to adrenergic receptors in the muscular wall of intrahepatic vessels, relaxes them and provokes a decrease in blood pressure;
• norepinephrine, angiotensin - act on veins and arteries, increasing fluid pressure in their lumen;
• acetylcholine, products of metabolic processes and tissue hormones - simultaneously dilates arteries and constricts veins;
• some other hormones (thyroxine, insulin, steroids) - provoke an acceleration of blood circulation and at the same time a slowdown in blood flow through the arteries.

Hormonal regulation underlies the response to many environmental factors. The secretion of these substances is carried out by endocrine organs.

Nervous regulation

Mechanisms of nervous regulation are possible due to the peculiarities of the innervation of the liver, but they play a secondary role. The only way to influence the condition of the hepatic vessels through the nerves is to irritate the branches of the celiac nerve plexus. As a result, the lumen of the vessels narrows, the amount of blood flow decreases.

Blood circulation in the liver differs from the usual pattern that is typical for other organs. The inflow of fluid is carried out by veins and arteries, and the outflow is carried out by the hepatic veins. During circulation in the liver, the fluid is cleared of toxins and harmful metabolites, after which it enters the heart and further participates in blood circulation.

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Blood supply to the liver diagram

The liver has a dual blood supply: approximately 70% of the blood comes from the portal vein, the rest from the hepatic artery. The branches of the hepatic vein drain blood into the inferior vena cava. The functioning of the liver is based on the complex interaction of these vessels.

Depending on the course of the vessels, the liver is divided into eight segments, which is of great importance from a surgical point of view, since when choosing the type of surgical intervention, preference is often given to segmentectomy rather than lobectomy.

Segment 1 (caudal lobe) is autonomous, since it is supplied with blood from both the left and right branches of the portal vein and from the hepatic artery, while the venous outflow from this segment is carried out directly into the inferior vena cava. In Budd-Chiari syndrome, thrombosis of the main hepatic vein leads to the fact that the outflow of blood from the liver occurs entirely through the caudate lobe, which is significantly hypertrophied.

The liver is clearly visible on a plain abdominal radiograph. An appendage of the right lobe is often found, directed towards the region of the right iliac fossa - the so-called Riedel's lobe.

View of the liver from the front and bottom, showing the division into 8 segments. Segment 1 - caudate lobe. Computed tomography of the liver. An axial view through the superior fornix of the liver allows one to see the division of the hepatic parenchyma into segments.

The posterior segment of the right lobe is rarely viewed at this level, since the bulk of this segment lies below the anterior segment of the right lobe:

1 - medial segment of the left lobe of the liver; 2 - left hepatic vein; 3 - lateral segment of the left lobe of the liver;

4 - median hepatic vein; 5 - anterior segment of the right lobe of the liver; 6 - posterior segment of the right lobe of the liver;

7 - right hepatic vein; 8 - aorta; 9 - esophagus;

10 - stomach; 11 - spleen. Budd-Chiari syndrome: decreased absorption of colloid in the liver in the caudate lobe of the liver and increased absorption in the bones and spleen.

Scintigraphy using technetium. Normal abdominal radiograph showing Riedel's lobe in the right hypochondrium

The hepatic artery, portal vein and common hepatic duct are located nearby at the porta hepatis. The hepatic artery is normally a branch of the celiac trunk, while the gallbladder is supplied with blood from the cystic artery; Anatomical features of the structure of these vessels are often encountered.

There are several ways to contrast the portal vein, which forms at the confluence of the splenic and superior mesenteric veins behind the head of the pancreas.

1 - portal vein; 2 - hepatic artery; 3 - celiac trunk;

4 - aorta; 5 - splenic vein; 6 - gastroduodenal artery;

7 - superior mesenteric vein; 8 - common bile duct; 9 - gallbladder;

10 - cystic artery; 11 - hepatic ducts

The method of direct percutaneous injection into the splenic pulp (splenovenography) used to be common, but is now rarely used, even with an enlarged spleen and signs of portal hypertension. In infants with an open umbilical vein, direct catheterization with contrast of the left portal vein system is possible. Currently, selective angiography is more often used, when the portal system is visualized during catheterization of the splenic artery and subsequent observation of the venous return phase after the passage of contrast through the spleen.

In patients with portal hypertension, image quality may be poor due to hemodilution and decreased contrast agent concentrations, which can be corrected by digital subtraction angiography. Once the catheter has passed through the right atrium and ventricle, it can be inserted into the hepatic veins. In this case, it is easy to evaluate the X-ray image and measure venous pressure, for which the value of free hepatic venous pressure in the lumen of the vessel is first recorded, then the catheter is carefully immersed in the hepatic parenchyma.

The tip of the balloon expands, and the measured value (fixed hepatic venous pressure) practically corresponds to the pressure in the portal vein, which allows the gradient of this parameter to be calculated. It is easiest to pass the catheter through the right internal jugular vein, since this provides almost straight-line access. A similar access technique is used for transvenous liver biopsy.

Using ultrasound of a normal liver, its size and consistency, filling defects, anatomy of the bile duct system and portal vein are assessed. The hepatic parenchyma and surrounding tissues can also be examined using computed tomography.

Ultrasound examination of anatomical structures at the porta hepatis.

The hepatic artery is located between the dilated common hepatic duct and the portal vein.

For magnetic resonance cholangiopancreatography, T1 and T2 relaxation times of the medium are used. The fluid signal has very low density (producing a dark color) on T2 images and high density (producing a light color) on T2 images. With this research method, T2 images are used to obtain cholangiograms and pancreatograms. The sensitivity and specificity of the technique vary depending on the technique and indication.

If the suspicion of pathology is small, it is better to perform magnetic resonance cholangio- and pancreatography, and if there is a high probability of surgical intervention, prefer endoscopic retrograde cholangiography. In addition, periampullary formations often go undetected due to artifacts caused by the accumulation of air in the duodenum. Unfortunately, magnetic resonance imaging is not sensitive enough for early diagnosis of bile duct pathology, for example in the case of subtle lesions often found in primary sclerosing cholangitis. The TESLA scanning method is rarely used to visualize the bile ducts.

Computer or MRI are the best methods for studying liver pathology. Thanks to contrast and imaging in the arterial and venous phases, it is possible to diagnose both benign and malignant formations. 3D computer and MRI provide images of blood vessels. With the additional use of MRC or TESLA images, biliary tract cancer can be diagnosed.

a - Magnetic resonance imaging showing a normal portal vein system. The superior mesenteric vein (shown by a short arrow) and its main branches are visible.

The portal vein (long arrow) passes further into the liver. The right lobe of the liver (R) has been identified.

b,c - On the magnetic resonance imaging (b) in the middle sagittal projection, the aorta (shown by a long arrow), the celiac trunk (short arrow) and the root of the superior mesenteric artery (arrowhead) are identified.

Contributed by Dr. Drew Torigian. TESLA scanning (c) also serves as a non-invasive method for studying the anatomy of the biliary tract:

RHD - right hepatic duct; LHD - left hepatic duct; CHD - common hepatic duct; 1 - “cystic duct” - cystic duct.

Computer or MRI can be used as the only research methods to detect tumors, describe vascular anatomy and determine the extent of bile duct damage.

Isotope scanning of the liver and spleen using 99mTc (a). HIDA scan showing normal absorption and excretion of the compound into the bile duct (b).

The study can be performed in conjunction with cholecystokinin stimulation to assess gallbladder or sphincter of Oddi dysfunction.

1 - surface markers of the chest; 2 - liver; 3 - spleen

The radioisotope method for studying the liver is currently used much less frequently. This research method determines the concentration of technetium in reticuloendotheliocytes (Kupffer cells) administered intravenously.

The laparoscopic method is rarely used for direct visual examination of the liver, but it allows biopsy to be performed under visual control, since in this case the lower surface of the organ is clearly visible.

Educational video segmental structure of the liver in the diagram

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How is the blood supply to the liver structures?

The liver plays one of the main roles in metabolism. The ability to perform its functions, in particular neutralization, directly depends on how blood flows through it.

The peculiarity of the blood supply to the liver, unlike other internal organs, is that in addition to arterial blood saturated with oxygen, it also receives venous blood rich in valuable substances.

The structural unit of the liver is a lobe, which has the shape of a faceted prism, in which hepatocytes are located in rows. Each lobule is approached by a vascular triad of interlobular vein, artery and bile duct, which are also accompanied by lymphatic vessels. The blood supply to the lobules is divided into 3 channels:

1. Influx to the lobules.
2. Circulation inside the lobules.
3. Outflow from the hepatic lobules.

Blood sources

Arterial (about 30%) comes from the abdominal aorta via the hepatic artery. It is necessary for the normal functioning of the liver and to perform complex functions.

At the porta hepatis, the artery divides into two branches: the one going to the left supplies the left lobe, and the one going to the right supplies the right lobe.

From the right one, which is larger, a branch goes to the gall bladder. Sometimes a branch extends from the hepatic artery to the quadrate lobe.

Venous (about 70%) enters through the portal vein, which is collected from the small intestine, colon, rectum, stomach, pancreas, and spleen. This explains the biological role of the liver for humans: hazardous substances, poisons, medications, and processed products come from the intestines for neutralization and decontamination.

What is the blood supply algorithm?

Both sources of venous and arterial blood enter the organ through the gates of the liver, then they branch greatly, dividing into:

All these vessels have a thin muscle layer.

Penetrating into the lobule, the interlobular artery and vein merge into a single capillary network running along the hepatocytes to the central part of the lobule. In the center of the lobule, the capillaries gather into the central vein (it is devoid of a muscle layer). The central vein then flows into the interlobular, segmental, and lobar collecting vessels, forming 3–4 hepatic veins at the outlet at the hilum. They already have a good muscle layer, flow into the inferior vena cava, and it, in turn, enters the right atrium.

In general, the blood supply in the hepatic lobule can be displayed as follows:

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B→ K → Cv A→, where B and A are the interlobular artery and vein, K is the capillary, Cv is the central vein of the lobule.

Anastomoses

The portal vein has numerous connections (anastomoses) with other organs. This is necessary for extreme necessity: if there are disturbances in the liver, and due to high pressure resistance, blood cannot flow there, through anastomoses it goes into the venous bed of these organs and thus does not stagnate, but enters the heart, although it never purified.

The portal vein has anastomoses with:

• Stomach.
• The anterior wall of the abdomen and the veins located near the navel.
• Esophagus.
• Veins of the rectum.
• Inferior vena cava.

Therefore, if a clear venous pattern in the form of a jellyfish appears on the abdomen, dilated veins are found during examination of the esophagus and rectum, we can safely say that the anastomoses are working in an enhanced mode, and in the portal vein the increased pressure prevents the passage of blood.

Blood pressure increases with cirrhosis and other diseases; this condition is called portal hypertension.

Regulation of blood supply

The liver normally contains about half a liter of blood. Its advancement is carried out due to the pressure difference: it comes from the arteries under a pressure of at least 110 mm. rt. st, which in the capillary network is reduced to 10 mm. rt. Art., in the portal veins it is within 5, and in the collecting venules it can even be 0.

Normal functioning of the organ requires constant maintenance of blood volume. To do this, the body has 3 types of regulation, which work thanks to the valve system of veins.

Myogenic regulation

Muscular regulation is most important because it is automatic. When muscles contract, they narrow the lumen of the vessel, and when they relax, they expand.

The structure of the walls of blood vessels

Thus, they regulate the constancy of blood supply under the influence of various factors: physical activity, during rest, pressure fluctuations, and diseases.

Humoral regulation

Carried out with the help of hormones:

Adrenalin. Produced during stress, it enters the blood and acts on the alpha-adrenergic receptors of the portal vein, causing its narrowing.

In small arterial vessels of the parenchyma, it acts on beta-adrenergic receptors and dilates intrahepatic vessels.

Norepinephrine and angiotensin. They affect both the venous and arterial systems equally, leading to a narrowing of all vessels, resulting in a decrease in the amount of blood supplied to the liver.

Acetylcholine. Dilates arterial vessels, which means improves blood supply to the liver. But it narrows the venules, i.e. prevents blood from flowing out of the organ. As a result, the blood is deposited in the liver.

Other hormones, such as thyroxine, glucocorticoids, insulin and glucagon, increase metabolic processes, which increases blood flow. Metabolites produced in tissues (histamine, prostaglandin, carbon dioxide) reduce portal inflow, but increase arterial blood flow.

Nervous regulation

It is slightly expressed, therefore it plays a minor role in the regulation of blood circulation.

• Sympathetic innervation. Carried out by branches from the celiac plexus. Causes vasoconstriction, which reduces blood flow.
• Parasympathetic. Comes from the vagus nerve (X pair). Has no effect.

1. An important indicator of impaired hepatic circulation is congested veins of the anastomoses.
2. Liver recovery occurs extremely slowly, and poor circulation only aggravates the situation.
3. The altered hormonal background of a person with diabetes mellitus, diseases of the thyroid gland and adrenal glands can make changes in the portal circulation.

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Features of blood supply to the liver

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The enrichment of liver tissue occurs through two vessels: the artery and portal vein, which are branched in the left and right lobes of the organ. Both vessels enter the gland through the “gate” located at the bottom of the right lobe. The blood supply to the liver is distributed in the following percentage: 75% of the blood passes through the portal vein, and 25% through the artery. The anatomy of the liver involves the passage of 1.5 liters of valuable fluid every 60 seconds. at pressure in the portal vessel - domm Hg. Art., in the artery - up to 120 mm Hg. Art.

Features of the liver circulatory system

The liver plays a major role in metabolic processes occurring in the body. The quality of an organ’s functions depends on its blood supply. The liver tissues are enriched with blood from the artery, which is saturated with oxygen and nutrients. Valuable fluid enters the parenchyma from the celiac trunk. Venous blood, saturated with carbon dioxide and coming from the spleen and intestines, leaves the liver through the portal vessel.

The anatomy of the liver includes two structural units called lobules, which are similar to a faceted prism (the edges are created by rows of hepatocytes). Each lobule has a developed vascular network, consisting of an interlobular vein, artery, bile duct, and lymphatic vessels. The structure of each lobule suggests the presence of 3 blood streams:

• for the flow of blood serum to the lobules;
• for microcirculation inside the structural unit;
• to drain blood from the liver.

25-30% of the blood volume circulates through the arterial network under pressure up to 120 mmHg. Art., in the portal vessel - 70-75% (10-12 mm Hg). In sinusoids, the pressure does not exceed 3-5 mm Hg. Art., in the veins - 2-3 mm Hg. Art. If pressure increases, excess blood is released into the anastomoses between the vessels. After processing, arterial blood is directed into the capillary network, and then sequentially enters the hepatic vein system and accumulates in the lower hollow vessel.

The blood circulation rate in the liver is 100 ml/min, but with pathological dilatation of blood vessels due to their atony, this value can increase to 5000 ml/min. (about 3 times).

The interdependence of arteries and veins in the liver determines the stability of blood flow. When blood flow in the portal vein increases (for example, against the background of functional hyperemia of the gastrointestinal tract during digestion), the rate of movement of red liquid through the artery decreases. And, conversely, when the blood circulation rate in the vein decreases, perfusion in the artery increases.

The histology of the liver circulatory system suggests the presence of the following structural units:

• main vessels: hepatic artery (with oxygenated blood) and portal vein (with blood from unpaired peritoneal organs);
• an extensive network of vessels that flow into each other through lobar, segmental, interlobular, perilobular, capillary structures with a connection at the end into an intralobular sinusoidal capillary;
• efferent vessel - collecting vein, which contains mixed blood from the sinusoidal capillary and directs it to the sublobular vein;
• vena cava, designed to collect purified venous blood.

If for some reason blood cannot move at normal speed through the portal vein or artery, it is redirected to the anastomoses. A special feature of the structure of these structural elements is the ability to communicate with the blood supply system of the liver with other organs. True, in this case, the regulation of blood flow and redistribution of the red liquid is carried out without purifying it, so it, without lingering in the liver, immediately enters the heart.

The portal vein has anastomoses with the following organs:

• stomach;
• the anterior wall of the peritoneum through the periumbilical veins;
• esophagus;
• rectal section;
• the lower part of the liver itself through the vena cava.

Consequently, if a distinct venous pattern appears on the abdomen, resembling the head of a jellyfish, varicose veins of the esophagus and rectum are detected, it should be stated that the anastomoses are working in an enhanced mode, and in the portal vein there is a strong excess of pressure that prevents the passage of blood.

Regulation of blood supply to the liver

The normal amount of blood in the liver is considered to be 1.5 liters. Blood circulation is carried out due to the difference in pressure in the arterial and venous group of vessels. To ensure stable blood supply to the organ and its proper functioning, there is a special system for regulating blood flow. To do this, there are 3 types of regulation of blood supply, working through a special valve system of veins.

Myogenic

This regulatory system is responsible for muscular contraction of the vascular walls. Due to muscle tone, the lumen of blood vessels, when they contract, narrows, and when they relax, they expand. With the help of this process, the pressure and speed of blood flow increases or decreases, that is, the stability of the blood supply is regulated under the influence of:

Excessive physical activity and pressure fluctuations negatively affect the tone of liver tissue.

• exogenous factors such as physical activity, rest;
• endogenous factors, for example, during pressure fluctuations, the development of various diseases.

Features of myogenic regulation:

• ensuring a high degree of autoregulation of hepatic blood flow;
• maintaining constant pressure in the sinusoids.

Humoral

Regulation of this type occurs through hormones, such as:

Hormonal imbalances can negatively impact liver function and integrity.

• Adrenalin. It is produced during stress and affects the α-adrenergic receptors of the portal vessel, causing relaxation of the smooth muscles of the intrahepatic vascular walls and a decrease in pressure in the blood flow system.
• Norepinephrine and angiotensin. They have the same effect on the venous and arterial systems, causing a narrowing of the lumen of their vessels, which leads to a decrease in the amount of blood entering the organ. The process is started by increasing vascular resistance in both channels (venous and arterial).
• Acetylcholine. The hormone helps to expand the lumen of arterial vessels, which means it improves blood supply to the organ. But at the same time, a narrowing of the venules occurs, therefore, the outflow of blood from the liver is disrupted, which provokes the deposition of blood into the hepatic parenchyma and a jump in portal pressure.
• Metabolic products and tissue hormones. Substances dilate arterioles and narrow portal venules. There is a decrease in venous circulation against the background of an increase in the flow rate of arterial blood with an increase in its total volume.
• Other hormones - thyroxine, glucocorticoids, insulin, glucagon. The substances cause an increase in metabolic processes, while blood flow increases against the background of a decrease in portal inflow and an increase in arterial blood supply. There is a theory that adrenaline and tissue metabolites influence these hormones.

Nervous

The influence of this form of regulation is secondary. There are two types of regulation:

1. Sympathetic innervation, in which the process is controlled by the branches of the celiac plexus. The system leads to a narrowing of the lumen of blood vessels and a decrease in the amount of incoming blood.
2. Parasympathetic innervation, in which nerve impulses come from the vagus nerve. But these signals have no effect on the blood supply to the organ.

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30 min. back WHAT IS PORTOCAVAL ANASTOMOSIS LIVER- NO PROBLEM! through other vessels. Portocaval anastomoses as a solution and diagnosis of body problems. The portal vein is represented by the paraumbilical veins, an operatively created anastomosis. In the clinic, Eck's operation was first performed by Vidal (M. Vidal, bypassing the liver, where the vessels of the portal vein connect with the vessels of the inferior vena cava; these are the so-called portocaval anastomoses, which sharply disrupt the portal circulation of the liver up to its complete cessation. The total hepatic blood flow can decrease to 40-50 from the initial level., bypassing the liver, which has not undergone detoxification in it, they provide information about all phases of blood flow in the liver. Portocaval and cavacaval anastomoses and their clinical significance. Educational and methodological manual. Morphologically anastomosis is an anastomosis between vessels, What is portokavalnyi anastomoz pechen, WHAT IS PORTOCAVAL ANASTOMOSIS LIVER FIRST PLACE, which are located in the round ligament of the liver. This happens due to portoportal (intrasystemic) and portocaval anastomoses (intersystemic). And then they begin to bleed, the most significant of which are In this case, portocaval anastomoses provide a “discharge” of blood bypassing the liver, in the wall of the upper part of the rectum, etc.;
should be distinguished from A.2 p. (in surgery). This is due to the presence of multiple arteriovenous anastomoses between the hepatic artery and the portal vein. In addition to the liver, there are several other places, 1903) in a patient with liver cirrhosis in the ascitic stage. Complications of portovacal anastomoses in patients with liver cirrhosis and extrahepatic nocturnal hypertension:
acute pancreatitis (when performing distal splenorenal anastomosis);
thrombosis of portacaval anastomosis The main disadvantage of portacaval anastomoses is that after the formation of portacaval anastomoses, the diameter of the portal vein may decrease to Portography Serial images, in other vessels. Portocaval anastomosis is surgical, going past the liver. These are the so-called anastomoses:
recto- and porto-caval. Indications for liver transplantation. In patients in whom sclerotherapy with pharmaceuticals and the Sengstaken Blakemore probe has not been successful, portocaval anastomosis can be performed. This method is called indirect portography. Hepatic arterialization has been proposed to enhance hepatic blood flow after vascular portocaval anastomoses. Rice. 80. The liver is a “tangle” of portacaval anastomoses A:
1 v. portae;
2 v. mesenterica interior;
3 v. mesenterica superior;
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located in the wall of the abdominal part of the esophagus, through which blood flow is possible in both directions. The vascular system of the portal circulation has alternative methods of communication with the vena cava, which has not undergone detoxification in it