Liver, hepar is an unpaired organ, the largest gland in the human body, belonging to the digestive system. It occupies a central place in the regulation and integration of interorgan metabolism and is the “central biochemical laboratory of the body.”
This important liver in the regulation of homeostasis of the whole organism is determined, first of all, by its topographic-anatomical location between the hepatic portal vein system (v. portae hepatis) and the inferior vena cava, v. cava inferior.
70% of the blood passing through the liver comes from v. portae hepatis (the rest - through the hepatic artery), due to which all compounds that are absorbed into the gastrointestinal tract must pass through the liver.
The functions of the liver are varied.
The most important of them are:
- Regulatory-homeostatic
- Biliary
- Urinary
- Excretory
- Neutralizing
- Participates in the regulation of the metabolism of carbohydrates, lipids, proteins, vitamins, and partly water-mineral substances, as well as in the metabolism of pigments, nitrogenous non-protein substances.
In the embryonic period of development, the liver plays the role of a hematopoietic organ. In addition, it also performs an endocrine function, producing somatomedin hormones, which are mediators of pituitary somatotropin and stimulate the growth of bones and muscles.
Liver topography
The liver is located in abdominal cavity on the right under the diaphragm in the right hypochondrium, regio hypochondrica dextra. It occupies most of the upper floor of the abdominal cavity. The left lobe reaches the left hypochondrium, regio hypochondrica sinistra. From above, the liver is adjacent to the diaphragm.Skeletotopia. There are upper, lower, left and right borders of the liver, which are projected onto the anterior wall of the body.
Upper limit. On the right, the liver is located at the level of the V costal cartilage and corresponds to the dome of the diaphragm; along the anterior midline of the body, the level of the upper border of the liver passes between the body of the sternum, corpus sterni, and the xiphoid process, processus xiphoideus; on the left, the upper edge of the left lobe of the liver corresponds to the VI costal cartilage.
Bottom line. On the left, the liver corresponds to the costal arch, arcus costalis, holding to the left, it emerges from under the costal arch at the junction of the cartilages of the VII and X ribs. Crossing the median plane, the lower border of the liver passes between the upper and middle thirds of the distance from the xiphoid process to the navel; on the left, the liver extends under the left costal arch at the junction of the cartilages of the VII and VIII left ribs.
Left border. The left border of the liver is determined in the middle between the sternal line, linea stemalis, and the left sternal line, linea parasternalis sinistra.
Right border. The right border of the liver runs along the midaxillary line, linea axilatis media, at the top it corresponds to the VII rib, and at the bottom it passes at the level of the XI rib. From behind, in the back area, the upper border of the liver is projected at the level of the lower edge of the IX thoracic vertebra, and the lower border is projected in the middle of the XI thoracic vertebra. During breathing, the liver moves up and down. Thus, when exhaling, the liver can rise by 3 cm. In some cases, the boundaries may fluctuate relative to the skeleton.
Syntopy. The upper surface of the liver is covered by the dome of the diaphragm. Adjacent to the lower surface are a number of organs that remain squeezed in. Within the right lobe of the liver there are three impingements: impressio colica from the transverse colon, behind this is the renal impingement, impressio renalis, from the upper pole of the right kidney, and more posteriorly and higher is the imprinting from the gl. suprarenalis - impressio suprarenale. The anterior wall of the stomach is adjacent to the lower surface of the left lobe of the liver, as a result of which a gastric squeeze is formed, impressio gastrica, and at the back, in a small area, the abdominal part of the esophagus forms an esophageal squeeze - impressio oesophagea. The goalkeeper, pylorus, is adjacent to the quadrate lobe, and behind the gate of the liver is the upper horizontal part, which on the sides of the gallbladder on the quadrate and right parts of the liver forms a duodenal squeeze, impressio duodenalis.
Thus, the following organs are adjacent to the lower surface of the liver (colon transversum, gap dexter, gl. Suprarenalis, gaster, pylorus et duodenum).
The liver is a parenchymal organ; it has a reddish-brown color, soft consistency, and its weight in an adult is 1.5-2 kg. There are two surfaces of the liver: the upper diaphragmatic, fades diaphragmatica, and the lower visceral, fades visceralis, which are separated from each other by the lower edge, margo inferior. The diaphragmatic surface is convex and is divided by the falciform ligament, lig. falcifore forme hepatis, into two parts - right and left, lobus hepatis dexter et sinister.
The lower surface of the liver is uneven, there are several pits and grooves on it from the organs that adjoin it. Tracing from right to left, we see the renal squeeze, impressio renalis, adrenal glands, impressio suprarenalis, colon, impressio colica, duodenum, impressio duodenalis, pyloric, impressio pylorica, and gastric, impressio gastrica. On the lower surface there are three grooves that divide the liver into four parts: two longitudinal grooves, sulcus longitudinalis dexter et sinister, and one deep transverse groove - the porta hepatis. The right longitudinal groove in the initial section is called the gallbladder fossa; the gallbladder is located here, and in the posterior part of this groove lies the inferior vena cava. In the left longitudinal groove lies the round ligament of the liver, lig. teres hepatis, in which the obliterated umbilical vein, vena umbilicalis, is located. Behind this groove there is a fibrous cord - the remnant of the venous strait, lig. venosum.
In the transverse recess or at the gate of the liver, porta hepatis, vessels, nerves and the bile duct pass. To the left of the longitudinal groove is the left lobe of the liver, lobus hepatis sinister, to the right of the right longitudinal groove is the right lobe, lobus hepatis dexter. Between the fissure of the round ligament, the porta hepatis and the fossa of the gallbladder lies the quadrate lobe, lobus quadratus hepatis. The caudate lobe of the liver, lobus qaudatus hepatis, located between the porta hepatis, the fissure of the venous ligament and the groove of the inferior vena cava.
The liver is covered with a fibrous membrane, tunica fibrosa, which is tightly fused with the visceral layer of the peritoneum. The peritoneum covers the entire liver with the exception of the posterior part of the diaphragmatic surface and passes to neighboring organs, where it forms a number of ligaments: - Crescent ligament, lig. falciforme hepatis;
- Crown, lig. coronarium hepatis;
- Right and left triangular, lig. triangulare dextrum et sinistrum,
- Hepatoduodenal, lig. hepatoduodenal
- Hepatic-renal, lig. hepatorenal.
The liver parenchyma is formed by hepatic lobules, lobus hepatis, which are the structural and functional units of the liver. Between the lobules there is interlobular connective tissue, which forms the stroma of the organ. The hepatic lobules have the shape of hexagonal prisms with a flat base and a convex apex, 1.5 mm wide and slightly higher in height. The hepatic lobules are built from hepatic beams and lobular sinusoidal hemocapillaries. The hepatic beams consist of two rows of liver cells - hepatocytes. The hepatic beams and sinusoidal hemocapillaries are located in the radial direction, from the periphery to the center, where the central vein, v. centralis. Intralobar sinusoidal blood capillaries lined with flat endothelial cells. At the junction of endothelial cells one with the other there are fenestrae. These areas of the endothelium are called sieve-like areas. Between the rows of liver cells (hepatocytes) there are bile capillaries with a diameter of 0.5-1 microns. Bile capillaries do not have their own wall, but are limited by the plasmalemma of neighboring hepatocytes. Bile capillaries originate at the central end of the hepatic beam, pass along it, reach the periphery of the hepatic lobule and pass into cholangioles - short tubes that flow into the interlobular bile ducts, ductus interlobularis biliferi. There are about 500 thousand particles in the human liver, their width is 1.5 mm. The lobules of the liver are separated from each other by layers of connective tissue, which in humans are poorly developed. Intensive growth interlobular connective tissue in humans leads to a disease - cirrhosis of the liver.
Segmental structure of the liver. In the liver, in addition to lobes and lobules, segments are distinguished. In clinical practice, the scheme of segmental division of the liver in the portal system is widespread. According to Quino (1957), it has two parts (right and left), five sectors and eight segments.
A liver segment is considered to be a pyramidal section of its parenchyma adjacent to the so-called hepatic triad (a second-order branch of the portal vein, a branch of the proper hepatic artery that accompanies it, and the corresponding branch of the hepatic strait).
Starting from the groove of the vena cava, sulcus venae cavae, on the left there are:- Caudate segment of the left lobe;
- Posterior segment of the left lobe;
- Anterior segment of the left lobe;
- Square segment of the left lobe;
- Middle upper anterior segment of the right lobe;
- Lateral inferoanterior segment of the right lobe;
- Lateral infero-posterior segment of the right lobe;
- Middle superoposterior segment of the right lobe.
The segments are located around the gates of the liver along radii and are part of more independent areas of the liver - sectors.
Blood supply liver is carried out from two sources: the own hepatic artery, a. hepatica propria (branch of a. hepatica communis) and the portal vein, vena portae, which branch in the parenchyma of the gland to the hemocapillaries. The portal vein carries about 75% of the total blood flow through the liver. The portal vein brings blood from the unpaired abdominal organs and delivers substances absorbed in the intestines to the liver. The proper hepatic artery brings oxygenated blood from the aorta. In the liver parenchyma, these vessels branch into smaller ones: lobular, segmental, interlobular, perilobular, veins and arteries. These vessels are accompanied by bile ducts, ductuli biliferi. Branches of the portal vein, hepatic artery and bile ducts form so-called triads, next to which lymphatic vessels pass.
Interlobular veins and arteries run along the lateral edges of the particles, and perilobular veins extend and limit the lobules at different levels. From the perilobular veins and arteries, hemocapillaries begin, entering the hepatic lobules and merging, forming sinusoidal hemocapillaries through which blood flows from the periphery to the center of the particles. Lobulated sinusoidal hemocapillaries pass between the strands of hepatic cells radially and flow into the central vein located in the center of the hepatic lobule.
Thus, sinusoidal hemocapillaries are located in the liver lobules between two venous systems - the portal vein system (perilobular veins) and the hepatic vein system (central veins). These hemocapillaries form the so-called “strange network”, rete mirabile. Blood from the lobules flows into the collecting or sublobular veins. The sublobular veins merge to form the hepatic veins, vv. hepaticae. The latter, 3-4 in number, flow into the inferior vena cava. Along the entire course, the branches of the portal vein and hepatic artery are accompanied by the hepatic ducts.
Lymphatic vessels. Lymph flows from the liver through deep and superficial lymphatic vessels. Superficial lymphatic vessels pass through the liver capsule, forming lymphatic networks. Deep lymphatic vessels are located around the hepatic lobules and branches of the hepatic artery, portal vein and bile duct. The lymphatic capillaries of the fibrous capsule anastomose from the interlobular capillaries. There are no lymphatic capillaries inside the hepatic lobes. The lymphatic vessels of the right and left lobes of the liver flow into regional nodes.
IN right lobe the lymphatic vessels of the capsule are divided into three groups: the anterior ones reach the hepatic nodes, nodi hepatici, and anastomose with the lymphatic vessels of the gallbladder and the capsule of the visceral surface of the liver; the middle ones are directed to the falciform ligament, and then penetrate the diaphragm and approach the phrenic and lower parasternal nodes; the posterior ones are directed to the coronary triangular ligament of the liver, partially enter the abdominal nodes, and some of them penetrate the diaphragm and reach the posterior mediastinal nodes.
In the left lobe of the liver, the lymphatic vessels are also divided into three groups: the anterior parts are directed into the lesser omentum to the right gastric lymph nodes; medial - in the falciform ligament they are combined with the vessels of the same name in the right lobe; posterior ones - go to the left gastric and partially to the diaphragmatic nodes. The lymphatic vessels of the visceral surface of the liver (right, caudate and quadrate lobes) drain lymph to the hepatic nodes, nodi hepatici, and partially to the left gastric nodes. The deep lymphatic vessels are divided into two groups: the first are located around the branches of the hepatic artery, portal vein and bile duct and leave the liver through its gates, where they join the hepatic nodes, the second are located in the connective tissue around the branches of the hepatic vein (including the collection vein). They pass at the mouth of the hepatic veins and are combined with the gastrointestinal nodes.
Innervation The liver is carried out by the vagus nerves, branches of the abdominal and inferior phrenic plexuses and the right phrenic nerve. The greater and lesser abdominal nerves carry out the sympathetic innervation, vagus nerves - parasympathetic. Branches vagus nerves The abdominal plexus in the area of the porta hepatis forms the anterior and posterior hepatic plexuses. The anterior hepatic plexus is located in lig. hepatoduodenal along a. hepatica, and the posterior one - along the portal vein. These plexuses are widely anostomous to each other.
The branches of the right phrenic nerve pass through the inferior vena cava and enter the organs through the coronary ligament. Its fibers are part of the hepatic plexuses and represent sources of efferent innervation of the gallbladder and liver. This fact explains the irradiation of pain to the right supraclavicular region in diseases of the gallbladder and liver (phrenicus symptom or Mussi-Georgievsky symptom).
X-ray anatomy of the liver
During x-ray examination the liver is depicted as a shadow formation in accordance with its position. IN modern conditions Using the ultrasound method (ultrasound) and X-ray computed tomography (CT), it is possible to determine the size, shape and structure of these organs. IN clinical settings The method of cholangiography (injection of contrast agents) detects the bile ducts, gallbladder, and the presence of stones in them.On radiographs, the liver has an intense, uniform shadow. The contour of the diaphragmatic surface of the liver merges with the shadow of the right half of the diaphragm. The external and anterior contours of the right lobe of the liver are smooth and clear. The lower contour of the liver corresponds to its anterior edge - from the shadow to the spine it is directed downwards and outwards; on it one can trace the depression in the area of the porta hepatis and the fossa of the gallbladder. The lower contour forms an acute angle, not more than 60 °.
The left lobe of the liver in adults is projected onto the shadow of the spine and therefore is visible mainly in the left lateral projection, where the shadow has the shape of a triangle, with its base facing the anterior slope of the diaphragm, one side facing the anterior abdominal wall, and the second - to the anterior wall of the stomach. In children, the left lobe of the liver is large and its shadow lies to the left of the image of the spinal column.
Image of the liver in a plane perpendicular to longitudinal axis body, obtained using computed tomography.
Ultrasound examination (ultrasound) of the liver
Ultrasound examination of the liver is carried out by successive scans (slices) in different planes. Since most of the liver is covered by the ribs, studies are carried out through “windows” accessible to ultrasound. This is primarily the right hypochondrium and epigastric area.Ecoanatomically, two lobes are distinguished in the liver: the right - large and the left - smaller. The falciform ligament is the boundary between the right and left lobes. On the scanogram it looks like a narrow echo-positive strip. In its anterior part there is a fibrous cord - the round ligament of the liver, which on a scanogram looks like a hyperechoic formation of an oval or round shape. In horizontal sections, the liver has a wedge-shaped shape. Its upper surface corresponds to the arch of the diaphragm, the lower is slightly concave. On the lower surface of the liver there are two longitudinal depressions and one transverse. The true dimensions of the liver, according to S. L. Hagen-Ansert (1976), are: transverse - 20-22.5 cm; vertical right lobe - 15-17.5 cm; anterior-posterior (at the level of the upper pole of the right kidney) - 10-12.5 cm.
Normally, the contour of the liver is clear and even. Its front surface is curved; the back is concave. The liver parenchyma is normally homogeneous, conducts sound well, and contains a lot of small and medium-sized echostructures, the appearance of which is due to the presence of vessels, ligaments and large bile ducts. The branches of the portal vein are always clearly visible; they are directed parallel to the anterior abdominal wall. The hepatic veins are located fan-shaped at an angle to the anterior abdominal wall. The hepatic arteries are identified in a small segment, directly at the portal of the liver. They look like small tubular formations (structures) with a diameter of 1-1.5 mm, directed parallel to the right and left branches of the portal system of the liver. Intrahepatic ducts are normally not detected, except in the area of the hilum where the right and left hepatic ducts merge.
Computed tomography (CT) of the liver
CT scan liver allows you to vialize the entire organ from its upper border (the arch of the diaphragm) to the end of the caudate lobe. Sections are made after administration of a contrast agent. Computed tomographs are used to determine the size of the liver, its relief, visualize the vessels, and also carry out three-dimensional reconstructions necessary for studying complex anatomical areas, for example, such as the porta hepatis.On computed tomograms, the liver has clear contours and a homogeneous structure. Blood vessels appear as areas of low attenuation compared to the liver parenchyma. Well defined
its right and left parts. The shape of the liver changes depending on the level of the section on the tomogram. At the Th XII level, the liver has an indefinite shape, the bulk of the organ is represented by right side. It occupies most of the abdominal cavity, its contour on the right is convex, and from below it is concave and uneven. In the anterior sections of the section, to the left of the midline, the vault of the stomach is determined, located under the left half of the dome of the diaphragm. At the Th X-XI level, the left lobe of the liver begins to emerge, delimited from the right lobe by the falciform ligament. The upper border of the liver passes through the right arch of the diaphragm and corresponds to the position of the IX-X thoracic vertebra. Majority blood vessels are represented by the hepatic veins and branches of the portal vein, which is determined at the level of Th XII-L I. A cross-section of the inferior vena cava is visible along the posterior edge of the liver. The gallbladder on tomograms is in most cases clearly visible in the form of a round or ellipsoidal formation with low density. The bile ducts normally do not appear on tomograms.
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Liver (hepar) - the largest gland in the body (weighs up to 1.5 kg), has a dark brown color. It performs various functions in the human body.
In the embryonic period, hematopoiesis occurs in the liver, which gradually fades towards the end. intrauterine development, and after birth it stops.
After birth and in adulthood, liver functions are mainly related to metabolism. It produces bile, which enters the duodenum and is involved in the digestion of fats.
The liver synthesizes phospholipids necessary for building cell membranes, in particular in nervous tissue; cholesterol is converted into bile acids. In addition, the liver is involved in protein metabolism; it synthesizes a number of blood plasma proteins (fibrinogen, albumin, prothrombin, etc.).
Glycogen is formed from carbohydrates in the liver, which is necessary to maintain blood glucose levels. Old red blood cells are destroyed in the liver. Macrophages absorb harmful substances and microorganisms from the blood.
One of the main functions of the liver is to detoxify substances, in particular phenol, indole and other decay products absorbed into the blood in the intestines. Here, ammonia is converted into urea, which is excreted by the kidneys.
Liver location
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Rice. 4.18.b.
Most of the liver is located in the right hypochondrium, the smaller part extends to the left side of the peritoneal cavity.
The liver is adjacent to the diaphragm, reaching level IV on the right and level V on the left of the intercostal space (see Fig. 4.18 B).
Its lower right thin edge protrudes slightly from under the right hypochondrium only when taking a deep breath. But even then it is impossible to palpate a healthy liver through the wall of the abdomen, since it is softer than the latter. In a small area (“under the stomach”) the gland is adjacent to the anterior abdominal wall.
rice. 4.18 B.
Projections of the liver, stomach and large intestine onto the surface of the body:
1 - stomach,
2 - liver,
3 - large intestine.
Surfaces and grooves of the liver
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There are two surfaces of the liver: upper - diaphragmatic and lower - visceral. They are separated from each other by a sharp anterior edge and a blunt posterior one.
Diaphragmatic surface of the liver facing up and forward. It is divided longitudinally falciform ligament into two unequal parts: more massive - right and smaller - left lobe(see Atl.).
Visceral surface of the liver concave, facing down and has impressions from neighboring organs.
Three grooves are visible on it: right And left longitudinal(sagittal) and located between them transverse, which form a figure resembling the letter H (see Atl.).
In the posterior part of the right longitudinal groove the inferior vena cava passes through, into which the hepatic veins open here.
In the anterior part of the same furrow lies the gallbladder.
Transverse groove is gates of the liver. Through them the hepatic artery, portal vein and nerves enter, and the bile ducts and lymphatic vessels exit. At the gate, all these formations are covered with serous leaves, which pass from them to the organ, forming its cover.
Behind the transverse groove located tailed, and ahead - square fraction, limited by sagittal grooves.
Ligaments of the liver
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Coronary ligament, running along the posterior edge of the liver, and mentioned falciform ligament(remnant of the ventral mesentery) connect the liver to the diaphragm. On the lower surface of the liver in the anterior part of the left longitudinal groove runs round ligament(overgrown umbilical vein of the fetus), which continues to the back of the groove, where it turns into venous ligament (overgrown venous duct connecting the fetal portal and inferior vena cava). The round ligament ends on the anterior abdominal wall near the navel. Ligaments running from the portal of the liver to the duodenum and to the lesser curvature of the stomach form small seal.
Liver coatings
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Most of the liver, with the exception of the posterior edge, is covered by peritoneum. The latter, continuing onto it from neighboring organs, forms ligaments that fix the liver in a certain position.
The posterior edge of the liver is not covered by peritoneum and is fused with the diaphragm. The connective tissue lying under the peritoneum forms a capsule that gives a certain shape to the liver, which continues into the liver tissue in the form of connective tissue layers.
Previously it was believed that the liver parenchyma consists of small formations called liver lobules(see Atl.). The diameter of the lobule is no more than 1.5 mm. Each slice in cross section has the shape of a hexagon, in the center of it there is a central vein, and along the periphery, at the points of contact of adjacent lobules, there are branches of the renal artery, portal vein, lymphatic vessel and bile duct. Together they form portal tracts. Neighboring lobules in animals are separated by layers of loose connective tissue. However, in humans such layers are not normally detected, which makes it difficult to determine the boundaries of the lobule.
Blood supply to the liver
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The portal vein brings blood to the liver from the unpaired abdominal organs: the digestive tract and the spleen. The branches of the hepatic artery follow the course of the branches of the portal vein. Surrounded by layers of connective tissue, they enter the liver, divide repeatedly and form interlobular branches from which capillaries extend. The latter have an irregular shape and therefore were called sinusoidal. They radially penetrate the lobules from the periphery to the center. Liver cells (hepatocytes) located in the lobule between the capillaries (Fig. 4.19). They fold into strands, or liver beams, directed radially. Capillaries pour blood into central vein, which penetrates the lobule longitudinally along the axis and opens into one of the collecting sublobular veins draining into the hepatic veins. These veins leave the liver on its posterior surface and empty into the inferior vena cava.
Rice. 4.19.Rice. 4.19. Fragment of the liver lobule
(arrows show the direction of blood movement in sinusoidal capillaries):
1 - central vein of the lobule;
2 - sinusoid,
3 - hepatic artery;
4 - branch of the portal vein;
5 - bile duct;
6 - bile capillary
Bile formation
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Between hepatocytes in the beams, blind-closed bile capillaries, going to gallducts, which connect and give rise to the right and left (corresponding to the lobes of the gland) hepatic ducts. The latter, merging, form common hepatic duct. Bile is secreted through this continuous system of ducts. The lymph formed in the liver is excreted through the lymphatic vessels.
Long-term studies of the structure of the liver lobules have shown that each hepatocyte faces one side of the bile capillary and the other side faces the wall of one or two sinusoids. The wall of each bile capillary is formed by a strand of two or three hepatocytes called trabecula(Fig. 4.19). Hepatocytes are tightly connected to each other by intercellular contacts. In other words, the capillary is a gap between the membranes of hepatocytes (Figure 4.20). Trabeculae, like the sinusoidal capillaries surrounding them, anastomose with each other. All of them are oriented from the periphery of the lobule to its center. Thus, blood from the interlobular branches of the portal vein and hepatic artery, lying in the portal tracts, enters the sinusoids. Here it mixes and flows to the central vein of the lobule.
Rice. 4.20.Rice. 4.20. Bile capillary limited by three hepatocytes.
(Electron microscopy × 13000):
1 - tight contact;
2 - desmosomes;
3 - granular endoplasmic reticulum;
4 - lysosome;
5 - mitochondria;
6 - smooth endoplasmic reticulum;
7 - lumen of the bile capillary
Bile secreted by hepatocytes into the bile capillaries moves along them to the bile duct located in the portal tract. Each bile duct collects bile from capillaries occupying a specific position in the classic hepatic lobules (Fig. 4.21, A). This area has approximately triangular shape and is called "portal lobule".
Rice. 4.21. Portal lobule (A) and acini (B) of the liver (schemes according to Ham, Cormack):
1 - portal tract;
2 — boundaries of the classic lobule;
3 - portal lobule (triangle-shaped);
4 - central vein;
5—acinus (diamond-shaped);
6 - network of blood vessels between the lobules;
7 - zones of hepatocytes receiving blood of different composition (I, II, III)
Functions of liver cells
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Liver cells perform a large number of functions related to ensuring metabolic processes in the body. In this regard, the blood supply to hepatocytes is of great importance. To facilitate understanding of this issue, the concept has been introduced "liver acinus" The acini includes 1/6 of two adjacent lobules (Fig. 4.21, B), it is shaped like a diamond. Passing through the sinusoids, the blood gives oxygen and nutrients to the hepatocytes of the hepatic beams, and takes away carbon dioxide and metabolic products from them. Therefore, one could assume that cells lying near the central veins of the lobules receive smaller amounts of these substances from the blood than cells located near the portal tracts. However, blood from the hepatic artery and portal vein, before entering the sinusoids, passes through a network of vessels of progressively decreasing diameter. These vessels penetrate the liver parenchyma and open into sinusoids. Thus, hepatocytes located near these vessels (zone I in Fig. 4.21, B), receive more substances from the blood than more distant zones (zones II and III). The part of the acinus located near the central vein receives the most depleted blood. This difference in blood supply leads to the fact that the metabolic processes in these zones of the acinus are somewhat different from each other. For lack of diet nutrients or the cells of these zones react differently to certain toxins: cells lying near the central veins are more vulnerable.
Substances brought to the liver with blood pass through the wall of sinusoidal capillaries and are absorbed by hepatocytes (Fig. 4.22). Between the wall of the sinusoid and the surface of hepatocytes there is a slit-like Disse space, filled with blood plasma. In the postnatal period, blood cells are not found here.
Rice. 4.22.Rice. 4.22. Scheme of the relationship between hepatocytes and sinusoidal capillaries in the hepatic beams:
1 - hepatocyte nucleus,
2 - Golgi complex;
3 - Disse space;
4 - endothelial cells;
5 - smooth endoplasmic reticulum;
6 - lysosomes;
7 - bile capillary;
8 - granular endoplasmic reticulum;
9 - Kupffer cells
Numerous microvilli of hepatocytes face this space. The wall of the sinusoids is formed by a single layer of two types of cells. These are mainly thin endothelial cells. Between them lie larger Kupffer cells. They develop from blood monocytes and perform the function of macrophages. In the cytoplasm of Kupffer cells, all organelles characteristic of macrophages can be distinguished: phagosomes, secondary lysosomes and enzymes are often found. The surface of the cell, facing the lumen of the sinusoid, is covered with a large number of microvilli. These cells cleanse the blood of foreign particles, fibrin, and activated blood clotting factors that have entered it. They are involved in the phagocytosis of red blood cells, the exchange of bile pigments, hemoglobin and steroid hormones.
Endothelial cells of the sinusoid wall have numerous pores in the cytoplasm (Fig. 4. 23.) There is no basement membrane.
Rice. 4.23.Rice. 4.23. Sinusoids and Disse space (scanning electron microscopy) (according to Hem, Cormack):
1 - hepatocyte;
2 - microvilli on the surface of the hepatocyte facing the space of Disse;
3 - fenestrated endothelium of the sinusoid.
Blood plasma components up to 100 nm in size penetrate through the pores. Due to the free flow of fluid from the lumen of the sinusoid into the space of Disse, equal pressure is created on the endothelial cells from the inside and outside and the sinusoid maintains its shape. The wall of the sinusoid is also supported by processes of cells that accumulate lipids (lipocytes or Ito cells). These cells lie near the sinusoids among hepatocytes and have the ability to synthesize collagen. For this reason, lipocytes may be involved in the development of liver cirrhosis. In addition, throughout the liver parenchyma, and around the sinusoids in particular, there are a large number of reticular fibers that perform a supporting function.
As already mentioned, the surface of hepatocytes facing the lumen of the sinusoid is covered with microvilli. They significantly increase the cell surface area required for absorption of substances from the bloodstream and secretion. The other secretory surface of the hepatocyte faces the bile capillary.
The functions of hepatocytes are diverse. In the presence of insulin, they are able to capture excess glucose from the bloodstream and deposit it in the cytoplasm in the form of glycogen. This process is stimulated by the adrenal hormone hydrocortisone. In this case, glycogen is formed from proteins and polypeptides. When there is a lack of glucose in the blood, glycogen is broken down and glucose is secreted into the blood. The cytoplasm of hepatocytes contains a large number of mitochondria, lysosomes, well-developed smooth and granular endoplasmic reticulum, microbodies
(vesicles) containing metabolic enzymes fatty acids. Hepatocytes remove excess lipoproteins from the blood plasma entering the space of Disse. They also synthesize blood plasma proteins: albumins, fibrinogen and globulins (except immunoglobulins) and are processed medications and chemical substances absorbed in the intestines, as well as alcohol and steroid hormones.
The liver produces large amounts of lymph, rich in proteins. Lymphatic vessels are detected only in the portal tracts; they are not found in the tissue of the hepatic lobules.
Bile secreted by hepatocytes into the lumen of the bile capillary is collected in small bile ducts located along the boundaries of the lobules. These ducts combine into larger ones. The walls of the ducts are formed by cubic epithelium surrounded by a basement membrane. As already mentioned, these ducts merge to form the hepatic ducts. Bile is secreted continuously (up to 1.2 liters per day), but in intervals between periods intestinal digestion is not directed to the intestine, but through the cystic duct, which extends from the hepatic duct, into the gallbladder.
Gallbladder
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The gallbladder has bottom(slightly protruding from under the lower edge of the right lobe of the liver), body and the narrowed part - neck, facing the gate of the liver (see Atl.). The bladder serves as a temporary reservoir of bile (capacity 60 cm3). Here it thickens due to the absorption of water by the walls of the bubble. With the onset of intestinal digestion, bile enters through the cystic duct into the common bile duct. The latter is formed from the connection of the cystic duct with the hepatic duct and opens into the duodenum at an elevation - the papilla (see Atl.). Often the common bile duct merges with the pancreatic duct. In the area of confluence, an expansion is formed - duct ampulla. The duct is equipped with two sphincters, formed by smooth muscles. One of them lies in the area of the papilla, and the other in the wall of the bile duct. Contraction of the second sphincter blocks the path of bile into the duodenum. It is drained through the cystic duct and accumulates in the gallbladder.
The gallbladder is lined with a mucous membrane that forms folds. These folds straighten out when the bubble stretches. The epithelium of the mucous membrane is formed by cylindrical absorptive cells. Their surface is covered with microvilli. The epithelium lies on a thin plate of connective tissue, under which there is a poorly developed muscular layer. The latter is formed by longitudinal and circular smooth muscle cells with numerous elastic fibers. The outside of the gallbladder is covered with connective tissue, which extends to the liver.
Bile, produced by the liver, emulsifies food fats and activates the fat-digesting enzyme of the pancreas, but does not contain enzymes itself.
, , , , , , , , , , ), is the largest of the digestive glands, occupies the upper part of the abdominal cavity, located under the diaphragm (see Fig.), mainly on the right side. The shape of the liver somewhat resembles the cap of a large mushroom; it has an upper convex and lower slightly concave surface. However, the convexity is devoid of symmetry, since the most protruding and voluminous part is not the central, but the right rear, which tapers anteriorly and to the left in a wedge-shaped manner. Dimensions of the liver: from right to left on average 26-30 cm, from front to back - right lobe 20-22 cm, left lobe 15-16 cm, greatest thickness (right lobe) - 6-9 cm. Liver weight is on average 1500 g. Color its red-brown, soft consistency.
In the liver there is a convex upper diaphragmatic surface, facies diaphragmatica, lower, concave in places, visceral surface, facies visceralis, spicy bottom edge, margo inferior, separating the upper and lower surfaces in front, and a slightly convex back part, pars posterior, diaphragmatic surface.
On the lower edge of the liver there is notch of the round ligament, incisura ligamenti teretis; To the right is a small notch corresponding to the adjacent bottom of the gallbladder.
Diaphragmatic surface, facies diaphragmatica(see Fig.), convex and corresponds in shape to the dome of the diaphragm. From the highest point there is a gentle slope to the lower sharp edge and to the left, to the left edge of the liver; a steep slope follows to the posterior and right parts of the diaphragmatic surface. Upwards, towards the diaphragm, there is a sagittally located peritoneal falciform ligament of the liver, lig. falciforme hepatis, which follows from the lower edge of the liver back over approximately 2/3 of the width of the liver; behind the leaves of the ligament diverge to the right and left, turning into coronary ligament of the liver, lig. coronarium hepatis. The falciform ligament divides the liver, according to its upper surface, into two parts - right lobe of the liver, lobus hepatis dexter, large and having the greatest thickness, and left lobe of the liver, lobus hepatis sinister, – smaller. On the upper part of the liver a small cardiac impression, impressio cardiaca, formed as a result of heart pressure and corresponding to the tendon center of the diaphragm.
On the diaphragmatic surface there are upper part, pars superior facing the tendon center of the diaphragm; anterior part, pars anterior, facing anteriorly, to the costal part of the diaphragm, and to the anterior wall of the abdomen in the epigastric region (left lobe); right side, pars dextra, directed to the right, towards the lateral abdominal wall (corresponding to the midaxillary line), and back part, pars posterior, facing towards the back.
Visceral surface, facies visceralis(see Fig. , , ), flat, slightly concave, corresponds to the configuration of the underlying organs. There are three grooves on it, dividing this surface into four lobes. Two grooves have a sagittal direction and stretch almost parallel to one another from the anterior to the posterior edge of the liver; approximately in the middle of this distance they are connected, as if in the form of a crossbar, by a third, transverse, furrow.
The left sulcus consists of two sections: the anterior, extending to the level of the transverse sulcus, and the posterior, located posterior to the transverse. Deeper anterior section - fissure of the round ligament, fissura lig. teretis(in the embryonic period - the umbilical vein groove), begins on the lower edge of the liver from cuttings of the round ligament, incisura lig. teretis, lies in it round ligament of the liver, lig. teres hepatis, running in front and below the navel and enclosing the obliterated umbilical vein. Posterior part of the left sulcus - fissure of the venous ligament, fissura lig. venosi(in the embryonic period - fossa ductus venosi, fossa ductus venosi), contains venous ligament, lig. venosum(obliterated ductus venosus), and stretches from the transverse groove back to the left hepatic vein. The left groove, in its position on the visceral surface, corresponds to the line of attachment of the falciform ligament on the diaphragmatic surface of the liver and, thus, serves here as the boundary of the left and right lobes of the liver. At the same time, the round ligament of the liver is located in the lower edge of the falciform ligament, on its free anterior section.
The right groove is a longitudinally located fossa and is called fossa of the gallbladder, fossa vesicae felleae, which corresponds to a notch on the lower edge of the liver. It is less deep than the groove of the round ligament, but wider and represents the imprint of the gallbladder, vesica fellea. The fossa extends posteriorly to the transverse groove; its continuation posterior to the transverse groove is groove of the inferior vena cava, sulcus venae cavae inferioris.
The transverse groove (see Fig. , ) is gate of the liver, porta hepatis. It contains the own hepatic artery, a. hepatis propria, common hepatic duct, ductus hepaticus communis, and portal vein, v. portae.
Both the artery and the vein are divided into main branches, right and left, already at the porta hepatis.
These three grooves divide the visceral surface of the liver into four lobes of the liver, lobi hepatis. The left groove delimits the lower surface of the left lobe of the liver to the right; the right groove demarcates on the left the lower surface of the right lobe of the liver.
The middle area between the right and left grooves on the visceral surface of the liver is divided by a transverse groove into anterior and posterior. The front section is square lobe, lobus quadratus, rear – caudate lobe, lobus caudatus.
On the visceral surface of the right lobe of the liver (see Fig.), closer to the anterior edge, there is colonic impression, impressio colica; behind, to the very rear edge, there are: to the right - a large depression from the right kidney adjacent here, renal impression, impressio renalis, to the left – adjacent to the right furrow duodenal (duodenal) impression, impressio duodenalis; even more posteriorly, to the left of the renal depression, - depression of the right adrenal gland, adrenal depression, impressio suprarenalis.
Quadrate lobe of the liver, lobus quadratus hepatis, limited on the right by the fossa of the gallbladder, on the left by the gap of the round ligament, in front by the lower edge, and behind by the porta hepatis. In the middle of the width of the square lobe there is a depression in the form of a wide transverse groove - an imprint of the upper part of the duodenum, a duodenal depression that continues here from the right lobe of the liver.
Caudate lobe of the liver, lobus caudatus hepatis, located posterior to the portal of the liver, limited in front by the transverse groove of the portal of the liver, on the right - groove of the vena cava, sulcus venae cavae, left – fissure of the venous ligament, fissura lig. venosi, and behind - the posterior part of the diaphragmatic surface of the liver. On the anterior portion of the caudate lobe on the left there is a small protrusion - papillary process, processus papillaris, adjacent to the back of the left side of the portal of the liver; on the right the caudate lobe forms caudate process, processus caudatus, which goes to the right, forms a bridge between the posterior end of the gallbladder fossa and the anterior end of the groove of the inferior vena cava and passes into the right lobe of the liver.
Left lobe of the liver, lobus hepatis sinister, on the visceral surface, closer to the anterior edge, has a convexity - omental tubercle, tuber omentale, which faces lesser omentum, omentum minus(see below). On the posterior edge of the left lobe, immediately next to the fissure of the ligamentum venosum, there is an impression from the adjacent abdominal part of the esophagus - esophageal depression, impressio esophageale.
To the left of these formations, closer to the back, on the lower surface of the left lobe there is gastric impression, impressio gastrica.
Posterior part of the diaphragmatic surface, pars posterior faciei diaphragmaticae(see Fig., ), is a rather wide, slightly rounded area of the surface of the liver. It forms a concavity corresponding to the place of contact with the spine. Its central section is wide, and narrows to the right and left. Corresponding to the right lobe there is a groove in which the inferior vena cava is located - groove of the vena cava, sulcus venae cavae. Closer to the upper end of this groove in the substance of the liver three hepatic veins, venae hepaticae, flowing into the inferior vena cava. The edges of the groove of the vena cava are connected to each other by the connective tissue ligament of the inferior vena cava (see Fig.).
The liver is almost completely surrounded by the peritoneum. Serous membrane, tunica serosa, covers its diaphragmatic, visceral surfaces and lower edge. However, in places where the ligaments approach the liver and the gallbladder is adjacent, there remain areas of varying widths that are not covered by the peritoneum. The largest area not covered by peritoneum is on the posterior part of the diaphragmatic surface, where the liver is directly adjacent to the posterior wall of the abdomen; it has the shape of a rhombus - extraperitoneal field, area nuda. Corresponding to its greatest width, the inferior vena cava is located. The second such area is located at the location of the gallbladder. Peritoneal ligaments extend from the diaphragmatic and visceral surfaces of the liver (for their description, see “Peritoneum”).
Liver, development (external and internal structure), topography, functions. Projection of the liver onto the surface of the body, the boundaries of the liver according to Kurlov. Structural and functional unit of the liver. Hepatic ducts. Common bile duct. Gallbladder: structure, topography, functions. X-ray anatomy. Age characteristics.
Liver (hepar located in the upper abdominal cavity, located under the diaphragm. Most of it occupies the right hypochondrium and the epigastric region, the smaller part is located in the left hypochondrium. The liver is wedge-shaped, red-brown in color and soft in consistency.
Functions: neutralization of foreign substances, providing the body with glucose and other energy sources (fatty acids, amino acids), glycogen depot, regulation of hydrocarbon metabolism, depot of some vitamins, hematopoietic (only in the fetus), synthesis of cholesterol, lipids, phospholipids, lipoproteins, bile acids, bilirubin, regulation of lipid metabolism, production and secretion of bile, blood depot in case of acute blood loss, synthesis of hormones and enzymes.
In it distinguish: the superior or diaphragmatic surface, the inferior or visceral, a sharp inferior edge (separating the superior and inferior surfaces in front), and the slightly convex posterior portion of the diaphragmatic surface. On the lower edge there is a notch of the round ligament and to the right a notch of the gallbladder.
The shape and size of the liver are not constant. In adults, the length of the liver on average reaches 25-30 cm, width - 15-20 cm and height - 9-14 cm. Weight on average 1500 g.
Diaphragmatic surface (faciesdiaphragmatica convex and smooth, corresponding in shape to the dome of the diaphragm. From the diaphragmatic surface upward, to the diaphragm, there is a peritoneal falciform (supporting) ligament (lig. falciforme hepatis), which divides the liver into two unequal lobes: the larger one, the right one, and the smaller one, the left one. At the back, the leaves of the ligament diverge to the right and left and pass into coronary ligament of the liver (ligcoronarium), which is a duplication of the peritoneum extending from the upper and posterior walls of the abdominal cavity to the posterior edge of the liver. The right and left edges of the ligament expand, take on the shape of a triangle and form right and left triangular ligaments (ligtriangularedextrumetsinistrum). On the diaphragmatic surface of the left lobe of the liver there is cardiac depression (impressioncardiaca, formed by the adherence of the heart to the diaphragm, and through it to the liver.
On the diaphragmatic surface of the liver there are top part facing the tendon center of the diaphragm, front part, facing anteriorly, to the costal part of the diaphragm and to the PBS (left lobe), right side, directed to the right towards the lateral abdominal wall, back facing the back.
Visceral surface (facies visceralis) flat and somewhat concave. There are three grooves on the visceral surface, dividing this surface into four lobes: right (lobus hepatis dexter), left (lobus hepatis sinister), square (lobus quadratus), and caudate (lobus caudatus). Two grooves have a sagittal direction and stretch along the lower surface of the liver almost parallel from the anterior to the posterior edge; in the middle of this distance they are connected in the form of a crossbar by a third, transverse groove.
The left sagittal groove is located at the level of the falciform ligament of the liver, separating the right lobe of the liver from the left. In its anterior section the groove forms gap round ligament (fissureligteretis), in which it is located round ligament of the liver (lig. teres hepatis) - overgrown umbilical vein In the posterior section - fissure of the venous ligament (fissura lig. venosi), in which it is located venous ligament (lig. venosum) - overgrown venous duct, which in the fetus connected the umbilical vein with the inferior vena cava
The right sagittal groove, unlike the left, is not continuous - it is interrupted by the caudate process, which connects the caudate lobe with the right lobe of the liver. In the anterior section of the right sagittal groove, a gallbladder fossa (fossavesicaefelleae), in which the gallbladder is located; This groove is wider in front; towards the back it narrows and connects with the transverse groove of the liver. In the posterior part of the right sagittal groove is formed groove of the inferior vena cava (sulcus v. cavae). The inferior vena cava is tightly fixed to the liver parenchyma by connective tissue fibers, as well as hepatic veins, which, upon leaving the liver, immediately open into the lumen of the inferior vena cava. The inferior vena cava, emerging from the hepatic groove, immediately goes into the chest cavity through the opening of the vena cava of the diaphragm.
Transverse groove or gate of the liver (portahepatis connects the right and left sagittal grooves. The gates of the liver include the portal vein, the proper hepatic artery, nerves, and the common hepatic duct and lymphatic vessels. All these vessels and nerves are located in the thickness of the hepatoduodenal and hepatogastric ligament.
The visceral surface of the right lobe of the liver has depressions corresponding to the organs adjacent to it: colonic depression, renal depression, duodenal depression, adrenal depression. On the visceral surface there are lobes: quadrate and caudate. Sometimes the cecum and appendix or loops of small intestines.
Square lobe of the liver (lobusqudratus bounded on the right by the fossa of the gallbladder, on the left by the fissure of the round ligament, in front by the lower edge, and behind by the porta hepatis. In the middle of the quadrate lobe there is a duodenal depression.
Caudate lobe of the liver (lobuscaudatus located posterior to the porta hepatis, bounded in front by the transverse groove, on the right by the groove of the vena cava, on the left by the fissure of the venous ligament, and behind by the posterior surface of the liver. They depart from the caudate lobe caudate process– between the porta hepatis and the groove of the inferior vena cava and papillary process– rests on the gate next to the gap of the venous ligament. The caudate lobe is in contact with the lesser omentum, the body of the pancreas and the posterior surface of the stomach.
Left lobe of the liver has a convexity on its lower surface - omental tubercle (tuberomentalis), which faces the lesser omentum. Depressions are also distinguished: esophageal depression as a result of the adherence of the abdominal part of the esophagus, gastric depression.
The posterior part of the diaphragmatic surface is represented by an area not covered by the peritoneum - extraperitoneal field. The back is concave, as a result of its attachment to the spinal column.
Between the diaphragm and the upper surface of the right lobe of the liver there is a slit-like space - hepatic bursa.
Boundaries of the liver according to Kurlov:
1. along the right midclavicular line 9 ±1cm
2. along the anterior midline 9 ±1cm
3. along the left costal arch 7 ±1cm
The upper limit of absolute liver dullness using the Kurlov method is determined only by the right midclavicular line; it is conventionally considered that the upper limit of the liver along the anterior midline is located at the same level (normally the 7th rib). The lower border of the liver along the right midclavicular line is normally located at the level of the costal arch, along the anterior midline - at the border of the upper and middle third of the distance from the navel to the xiphoid process, and along the left costal arch - at the level of the left parasternal line.
The liver is covered over a large area by the chest. In connection with the respiratory movements of the diaphragm, oscillatory displacements of the liver borders up and down by 2-3 cm are noted.
The liver is located mesoperitoneally. Its upper surface is completely covered with peritoneum; on the lower surface the peritoneal cover is absent only in the area where the grooves are located; the posterior surface is devoid of peritoneal cover for a considerable extent. The extraperitoneal part of the liver on the posterior surface is bounded above by the coronary ligament, and below by the transition of the peritoneum from the liver to the right kidney, right adrenal gland, inferior vena cava and diaphragm. The peritoneum covering the liver passes to neighboring organs and forms ligaments at the transition points. All ligaments, except the hepatorenal ligament, are double layers of peritoneum.
Ligaments of the liver:
1.Coronoid ligament (ligcoronarium directed from the lower surface of the diaphragm to the convex surface of the liver and is located at the border of the transition of the upper surface of the liver to the posterior one. The length of the ligament is 5-20 cm. On the right and left it turns into triangular ligaments. The coronary ligament mainly extends to the right lobe of the liver and only slightly extends to the left.
2. Falciform ligament (ligfalciforme stretched between the diaphragm and the convex surface of the liver. It has an oblique direction: in the posterior section it is located according to the midline of the body, and at the level of the anterior edge of the liver it deviates 4-9 cm to the right of it.
The round ligament of the liver runs through the free anterior edge of the falciform ligament, which runs from the umbilicus to the left branch of the portal vein and lies in the anterior part of the left longitudinal groove. During the period of intrauterine development of the fetus, the umbilical vein is located in it, receiving arterial blood from the placenta. After birth, this vein gradually becomes empty and turns into a dense connective tissue cord.
3. Left triangular ligament (lig. triangulare sinistrum stretched between the lower surface of the diaphragm and the convex surface of the left lobe of the liver. This ligament is located 3-4 cm anterior to the abdominal esophagus; on the right it passes into the coronary ligament of the liver, and on the left it ends with a free edge.
4. Right triangular ligament (lig. triangulare dextrum located on the right between the diaphragm and the right lobe of the liver. It is less developed than the left triangular ligament and is sometimes completely absent.
5. Hepatorenal ligament (lig. hepatorenale is formed at the junction of the peritoneum from the lower surface of the right lobe of the liver to the right kidney. The inferior vena cava passes through the medial part of this ligament.
6.Hepatogastric ligament (lig. hepatogastricum located between the porta hepatis and the posterior part of the left longitudinal groove above and the lesser curvature of the stomach below.
7. Hepatoduodenal ligament (lig. hepatoduodenale stretched between the porta hepatis and the upper part of the duodenum. On the left it passes into the hepatogastric ligament, and on the right it ends with a free edge. The ligament contains the bile ducts, hepatic artery and portal vein, lymphatic vessels and The lymph nodes, as well as nerve plexuses.
Fixation of the liver is carried out due to the fusion of its posterior surface with the diaphragm and the inferior vena cava, the supporting ligamentous apparatus and intra-abdominal pressure.
Structure of the liver: On the outside, the liver is covered with a serous membrane (visceral peritoneum). Under the peritoneum there is a dense fibrous membrane (Glisson's capsule). From the porta hepatis side, the fibrous membrane penetrates the substance of the liver and divides the organ into lobes, lobes into segments, and segments into lobules. The gates of the liver include the portal vein (collects blood from the unpaired abdominal organs) and the hepatic artery. In the liver, these vessels are divided into lobar, then into segmental, subsegmental, interlobular, perilobular. Interlobular arteries and veins are located close to the interlobular bile duct and form the so-called. hepatic triad. Capillaries begin from the periphery of the lobules and veins, which merge at the periphery of the lobules and form sinusoidal hemocapillary. Sinusoidal hemocapillaries in the lobules run radially from the periphery to the center and merge in the center of the lobules to form central vein. The central veins drain into the sublobular veins, which merge with each other to form the segmental and lobar hepatic veins, which drain into the inferior vena cava.
The structural and functional unit of the liver is liver lobule. There are about 500 thousand hepatic lobules in the human liver parenchyma. The hepatic lobule has the shape of a multifaceted prism, through the center of which runs the central vein, from which it diverges radially like rays liver beams (plates), in the form of double radially directed rows of liver cells - hepatocytes. Sinusoidal capillaries are also located radially between the hepatic beams; they carry blood from the periphery of the lobule to its center, i.e. the central vein. Inside each beam, between 2 rows of hepatocytes, there is a bile duct (canaliculus), which is the beginning of the intrahepatic biliary tract, which subsequently serves as a continuation of the extrahepatic biliary tract. In the center of the lobule near the central vein, the bile ducts are closed, and at the periphery they flow into the bile interlobular ducts, then into the interlobular bile ducts and as a result form the right hepatic bile duct, which removes bile from the right lobe, and the left hepatic duct, which removes bile from left lobe of the liver. After leaving the liver, these ducts give rise to the extrahepatic bile ducts. At the porta hepatis, these two ducts merge to form the common hepatic duct.
Based general principles The branching of the intrahepatic bile ducts, hepatic arteries and portal veins in the liver distinguishes 5 sectors and 8 segments.
Liver segment– a pyramidal section of the hepatic parenchyma surrounding the so-called hepatic triad: a branch of the portal vein of the 2nd order, the accompanying branch of the hepatic artery and the corresponding branch of the hepatic duct.
Liver segments are usually numbered counterclockwise around the porta hepatis, starting with the caudate lobe of the liver.
The segments, when grouped, are included in larger independent areas of the liver - sectors.
Left dorsal sector corresponds to C1 includes the caudate lobe and is visible only on the visceral surface and posterior part of the liver.
Left paramedian sector occupies the anterior part of the left lobe of the liver (C3) and its quadrate lobe (C4).
Left lateral sector corresponds to C2 and occupies the posterior portion of the left lobe of the liver.
Right paramedian sector is a hepatic parenchyma bordering the left lobe of the liver, the sector includes C5 and C8.
Right lateral sector corresponds to the most lateral part of the right lobe, includes C7 and C6.
Gallbladder (vesicafellea located in the fossa of the gallbladder on the visceral surface of the liver, it is a reservoir for the accumulation of bile. The shape is often pear-shaped, length 5-13cm, volume 40-60ml of bile. The gallbladder is dark green in color and has a relatively thin wall. .
There are: bottom of the gallbladder (fundus), which comes out from under the lower edge of the liver at the level of the VIII-IX ribs; neck of the gallbladder (collum– the narrower end, which is directed towards the gate of the liver and from which the cystic duct departs, connecting the bladder with the common bile duct; body of the gallbladder (corpus– located between the bottom and the neck. A bend forms at the junction of the body and the neck.
The upper surface of the bladder is fixed to the liver by connective tissue fibers, the lower surface is covered with peritoneum. Most often, the bladder lies mesoperitoneally, sometimes it can be covered with peritoneum on all sides and have a mesentery between the liver and the bladder.
The body and neck are adjacent to the upper part of the 12-RK at the bottom and sides. The bottom of the bubble and part of the body are covered with POC. The bottom of the bladder may be adjacent to the PBS when it protrudes from under the anterior edge of the liver.
Shells:
1. serous– peritoneum, passing from the liver, if there is no peritoneum – adventitia;
2.muscular– a circular layer of smooth muscles, among which there are also longitudinal and oblique fibers. Stronger muscle layer expressed in the cervical region, where it passes into the muscular layer of the cystic duct.
3.CO– thin, has a submucosal base. The CO forms numerous small folds; in the cervical area they become spiral folds and pass into the cystic duct. There are glands in the cervical area.
Blood supply: from the cystic artery (), which most often arises from the right branch of the hepatic artery. At the border between the neck and body, the artery divides into anterior and posterior branches, which approach the bottom of the bladder.
Arteries biliary tract(diagram): 1 - proper hepatic artery; 2 - gastroduodenal artery; 3 - pancreaticoduodenal artery; 4 - superior mesenteric artery; 5 - cystic artery.
The outflow of venous blood occurs through the cystic vein, which accompanies the artery of the same name and flows into the portal vein or its right branch.
Innervation: branches of the hepatic plexus.
Bile ducts:
1 -- ductus hepaticus sinister; 2 - ductus hepaticus dexter; 3 - ductus hepaticus communis; 4 - ductus cysticus; 5 - ductus choledochus; 6 - ductus pancreaticus; 7 - duodenum; 8 - collum vesicae felleae; 9 - corpus vesicae felleae; 10 - fundus vesicae felleae.
To the extrahepatic bile ducts relate: right and left hepatic, common hepatic, cystic and common bile. At the gates of the liver they emerge from the parenchyma right and left hepatic ducts (ductus hepaticus dexter et sinister). The left hepatic duct in the liver parenchyma is formed by the fusion of the anterior and posterior branches. The anterior branches collect bile from the quadrate lobe and the anterior part of the left lobe, and the posterior branches collect bile from the caudate lobe and the posterior part of the left lobe. The right hepatic duct is also formed from the anterior and posterior branches, which collect bile from the corresponding parts of the right lobe of the liver.
Common hepatic duct (ductus hepaticus communis), is formed by the fusion of the right and left hepatic ducts. The length of the common hepatic duct ranges from 1.5 to 4 cm, diameter - from 0.5 to 1 cm. As part of the hepatoduodenal ligament, the duct descends down, where it connects with the cystic duct to form the common bile duct.
Behind the common hepatic duct is the right branch of the hepatic artery; in rare cases it passes anterior to the duct.
Cystic duct (ductus cysticus), has a length of 1-5 cm, a diameter of 0.3-0.5 cm. It passes in the free edge of the hepatoduodenal ligament and merges with the common hepatic duct (usually at an acute angle), forming the common bile duct. The muscular layer of the cystic duct is poorly developed, and the CO forms a spiral fold.
Common bile duct (ductus choledochus), has a length of 5-8 cm, diameter - 0.6-1 cm. It is located between the leaves of the hepatoduodenal ligament, to the right of the common hepatic artery and anterior to the portal vein. In its direction it is a continuation of the common hepatic duct.
It distinguishes fourparts pars supraduodenalis, pars retroduodenalis, pars pancreatica, pars intramuralis
1. The first part of the duct is located above the 12th PC, in the free edge of the hepatoduodenal ligament. Near the duodenum, the gastroduodenal artery passes to the left of the duct.
2. The second part of the duct passes retroperitoneally, behind the upper part of the duodenum. In front, this part of the duct is crossed by the superior posterior pancreatic-duodenal artery, then it bends around the duct from the outside and passes to its posterior surface.
3. The third part of the duct most often lies in the thickness of the head of the pancreas, less often in the groove between the head of the gland and the descending part of the duodenum.
4. The fourth part of the duct passes through the wall descending department duodenum. On the mucous membrane of the duodenum, this part of the duct corresponds to a longitudinal fold.
The common bile duct opens, as a rule, together with the pancreatic duct at major duodenal papilla (papilla duodeni major). In the area of the papilla, the mouths of the ducts are surrounded by muscle - sphincter of hepatopancreatic ampulla. Before merging with the pancreatic duct, the common bile duct in its wall has sphincter of the common bile duct, blocking the flow of bile from the liver and gallbladder into the lumen of 12-PC.
The common bile duct and the pancreatic duct most often merge and form an ampulla 0.5-1 cm long. In rare cases, the ducts open into the duodenum separately.
The wall of the common bile duct has a pronounced muscular layer, there are several folds in the bile duct, and the bile glands are located in the submucosa.
The extrahepatic bile ducts are located in the duplication of the hepatoduodenal ligament along with the common hepatic artery, its branches and the portal vein. At the right edge of the ligament is the common bile duct, to the left of it is the common hepatic artery, and deeper than these formations and between them is the portal vein; In addition, between the leaves of the ligament lie lymphatic vessels and nerves. The division of the proper hepatic artery into the right and left hepatic arteries occurs in the middle of the length of the ligament, and the right hepatic artery is directed upward and lies under the common hepatic duct; at the place of their intersection, the cystic artery departs from the right hepatic artery, which is directed upward to the region of the angle formed by the confluence cystic duct into the common hepatic duct. Next, the cystic artery passes along the wall of the gallbladder.
Blood supply: cystic artery.
Innervation: hepatic plexus (sympathetic branches, branches of the vagus nerve, phrenic branches).
Liver, hepar, is the largest of the digestive glands, occupies the upper part of the abdominal cavity, located under the diaphragm, mainly on the right side.
By shape liver somewhat resembles the cap of a large mushroom, has an upper convex and lower slightly concave surface. However, the convexity is devoid of symmetry, since the most protruding and voluminous part is not the central part, but the right rear one, which tapers anteriorly and to the left in a wedge-shaped manner. Human liver dimensions: from right to left on average 26-30 cm, from front to back - right lobe 20-22 cm, left lobe 15-16 cm, greatest thickness (right lobe) - 6-9 cm. The weight of the liver is on average 1500 g. Its color is red -brown, soft consistency.
Structure human liver: there is a convex upper diaphragmatic surface, facies diaphragmatica, a lower, sometimes concave, visceral surface, facies visceralis, a sharp lower edge, margo inferior, separating the upper and lower surfaces in front, and a slightly convex rear part, pars posterior. diaphragmatic surface.
On the lower edge of the liver there is a notch of the round ligament, incisura ligaments teretis: to the right there is a small notch corresponding to the adjacent bottom of the gallbladder.
The diaphragmatic surface, facies diaphragmatica, is convex and corresponds in shape to the dome of the diaphragm. From the highest point there is a gentle slope to the lower sharp edge and to the left, to the left edge of the liver; a steep slope follows to the posterior and right parts of the diaphragmatic surface. Upwards, to the diaphragm, there is a sagittally located peritoneal falciform ligament of the liver, lig. falciforme hepatis, which follows from the lower edge of the liver back for about 2/3 of the width of the liver: behind the leaves of the ligament diverge to the right and left, passing into the coronary ligament of the liver, lig. coronarium hepatis. The falciform ligament divides the liver, according to its upper surface, into two parts - the right lobe of the liver, lobus hepatis dexter, which is large and has the greatest thickness, and the left lobe of the liver, lobus hepatis sinister, which is smaller. On the upper part of the liver one can see a small cardiac depression, impressio cardiaca, formed as a result of the pressure of the heart and corresponding to the tendon center of the diaphragm.
On the diaphragm liver surface distinguish the upper part, pars superior, facing the tendon center of the diaphragm; the anterior part, pars anterior, facing anteriorly, to the costal part of the diaphragm, and to the anterior wall of the abdomen in the epigastric region (left lobe); the right part, pars dextra, directed to the right, towards the lateral abdominal wall (corresponding to the mid-axillary line), and the back part, pars posterior, facing towards the back.
The visceral surface, facies visceralis, is flat, slightly concave, corresponding to the configuration of the underlying organs. There are three grooves on it, dividing this surface into four lobes. Two grooves have a sagittal direction and stretch almost parallel to one another from the anterior to the posterior edge of the liver; approximately in the middle of this distance they are connected, as if in the form of a crossbar, by a third, transverse, furrow.
The left sulcus consists of two sections: the anterior, extending to the level of the transverse sulcus, and the posterior, located posterior to the transverse. The deeper anterior section is the fissure of the round ligament, fissura lig. teretis (in the embryonic period - the groove of the umbilical vein), begins on the lower edge of the liver from the notch of the round ligament, incisura lig. teretis. it contains the round ligament of the liver, lig. teres hepatis, running in front and below the navel and enclosing the obliterated umbilical vein. The posterior section of the left groove is the fissure of the venous ligament, fissura lig. venosi (in the embryonic period - fossa ductus venosi, fossa ductus venosi), contains the venous ligament, lig. venosum (obliterated ductus venosus), and stretches from the transverse groove back to the left hepatic vein. The left groove, in its position on the visceral surface, corresponds to the line of attachment of the falciform ligament on the diaphragmatic surface of the liver and, thus, serves here as the boundary of the left and right lobes of the liver. At the same time, the round ligament of the liver is located in the lower edge of the falciform ligament, on its free anterior section.
The right groove is a longitudinally located fossa and is called the gallbladder fossa, fossa vesicae felleae, which corresponds to a notch on the lower edge of the liver. It is less deep than the groove of the round ligament, but wider and represents the imprint of the gallbladder located in it, vesica fellea. The fossa extends posteriorly to the transverse groove; its continuation posterior to the transverse groove is the groove of the inferior vena cava, sulcus venae cavae inferioris.
The transverse groove is the gate of the liver, porta hepatis. It contains the own hepatic artery, a. hepatis propria, common hepatic duct, ductus hepaticus communis, and portal vein, v. portae.
Both artery and vein are divided into main branches, right and left, already at the hilum liver.
These three grooves divide the visceral surface of the liver into four lobes of the liver, lobi hepatis. The left groove delimits the lower surface of the left lobe of the liver to the right; the right groove demarcates on the left the lower surface of the right lobe of the liver.
The middle area between the right and left grooves on the visceral surface of the liver is divided by a transverse groove into anterior and posterior. The anterior portion is the quadrate lobe, lobus quadratus, the posterior portion is the caudate lobe, lobus caudatus.
On the visceral surface of the right lobe of the liver, closer to the anterior edge, there is a colonic depression, impressio colica; behind, to the very rear edge, there are: to the right - a large depression from the right kidney adjacent here, the renal depression, impressio renalis, to the left - the duodenal (duodenal) depression, impressionio duodenalis, adjacent to the right groove; even more posteriorly, to the left of the renal depression, - depression of the right adrenal gland, adrenal depression, impressio suprarenalis.
The square lobe of the liver, lobus quadratus hepatis, is bounded on the right by the fossa of the gallbladder, on the left by the fissure of the round ligament, in front by the lower edge, and behind by the porta hepatis. In the middle of the width of the square lobe there is a depression in the form of a wide transverse groove - an imprint of the upper part of the duodenum, a duodenal depression that continues here from the right lobe of the liver.
The caudate lobe of the liver, lobus caudatus hepatis, is located posterior to the portal of the liver, limited in front by the transverse groove of the portal of the liver, on the right - by the groove of the vena cava, sulcus venae cavae, on the left - by the fissure of the venous ligament, fissura lig. venosi, and behind - the posterior part of the diaphragmatic surface of the liver. On the anterior portion of the caudate lobe on the left there is a small protrusion - the papillary process, processus papillaris, adjacent to the back of the left side of the porta hepatis; on the right, the caudate lobe forms the caudate process, processus caudatus, which goes to the right, forms a bridge between the posterior end of the gallbladder fossa and the anterior end of the groove of the inferior vena cava and passes into the right lobe of the liver.
The left lobe of the liver, lobus hepatis sinister, on the visceral surface, closer to the anterior edge, has a convexity - the omental tubercle, tuber omentale, which faces the lesser omentum, omentum minus. On the posterior edge of the left lobe, immediately next to the fissure of the venous ligament, there is a depression from the adjacent abdominal part of the esophagus - the esophageal depression, impressio esophageale.
To the left of these formations, closer to the back, on the lower surface of the left lobe there is a gastric impression, impressio gastrica.
The posterior part of the diaphragmatic surface, pars posterior faciei diaphragmaticae, is a rather wide, slightly rounded section of the surface of the liver. It forms a concavity corresponding to the place of contact with the spine. Its central section is wide, and narrows to the right and left. According to the right lobe, there is a groove in which the inferior vena cava is located - the groove of the vena cava, sulcus venae cavae. Closer to the upper end of this groove in the substance of the liver, three hepatic veins, venae hepaticae, are visible, flowing into the inferior vena cava. The edges of the groove of the vena cava are connected to each other by the connective tissue ligament of the inferior vena cava.
The liver is almost completely surrounded by the peritoneum. The serous membrane, tunica serosa, covers its diaphragmatic, visceral surfaces and lower edge. However, in places where the ligaments approach the liver and the gallbladder is adjacent, there remain areas of varying widths that are not covered by the peritoneum. The largest area not covered by peritoneum is on the posterior part of the diaphragmatic surface, where the liver is directly adjacent to the posterior wall of the abdomen; it has the shape of a rhombus - extraperitoneal field, area nuda. Corresponding to its greatest width, the inferior vena cava is located. The second such area is located at the location of the gallbladder. The peritoneal ligaments extend from the diaphragmatic and visceral surfaces of the liver.
The structure of the liver.
The serous membrane, tunica serosa, covering the liver, is underlain by the subserosal base, tela subserosa, and then by the fibrous membrane, tunica fibrosa. Through the portal of the liver and the posterior end of the gap of the round ligament, together with the vessels, connective tissue penetrates into the parenchyma in the form of the so-called perivascular fibrous capsule, capsula fibrosa perivascularis, in the processes of which there are bile ducts, branches of the portal vein and the proper hepatic artery; along the course of the vessels it reaches the fibrous membrane from the inside. This is how a connective tissue frame is formed, in the cells of which the liver lobules are located.
Liver lobule.
Liver lobule, lobulus hepaticus, 1-2 mm in size. consists of liver cells - hepatocytes, hepatocyti, forming liver plates, laminae hepaticae. In the center of the lobule is the central vein, v. centralis, and around the lobule there are interlobular arteries and veins, aa. interlobular et vv, interlobulares, from which interlobular capillaries originate, vasa capillaria interlobularia. Interlobular capillaries enter the lobule and pass into sinusoidal vessels, vasa sinusoidea, located between the hepatic plates. In these vessels arterial and venous (from v, portae) blood mixes. The sinusoid vessels empty into the central vein. Each central vein joins the sublobular, or collecting, veins, vv. sublobulares, and the latter - into the right, middle and left hepatic veins. vv. hepaticae dextrae, mediae et sinistrae.
Between the hepatocytes lie bile canaliculi, canaliculi biliferi, which flow into the bile ducts, ductuli biliferi, and the latter, outside the lobules, connect into interlobular bile ducts, ductus interlobulares biliferi. Segmental ducts are formed from the interlobular bile ducts.
Based on the study of intrahepatic vessels and bile ducts, a modern understanding of the lobes, sectors and segments of the liver has emerged. The branches of the portal vein of the first order bring blood to the right and left lobes of the liver, the border between which does not correspond to the external border, but passes through the fossa of the gallbladder and the groove of the inferior vena cava.
Second-order branches provide blood flow to the sectors: in the right lobe - to the right pyramidal sector, sector paramedianum dexter, and the right lateral sector, sector lateralis dexter; in the left lobe - into the left paramedian sector, sector paramedianum sinister, the left lateral sector, sector lateralis sinister, and the left dorsal sector, sector dorsalis sinister. The last two sectors correspond to liver segments I and II. The other sectors are each divided into two segments, so that there are 4 segments in the right and left lobes.
The lobes and segments of the liver have their own bile ducts, branches of the portal vein and their own hepatic artery. The right lobe of the liver is drained by the right hepatic duct, ductus hepaticus dexter, which has anterior and posterior branches, r. anterior et r. posterior, the left lobe of the liver - the left hepatic duct, ductus hepaticus sinister, consisting of medial and lateral branches, r. medialis et lateralis, and the caudate lobe - by the right and left ducts of the caudate lobe, ductus lobi caudati dexter et ductus lobi caudati sinister.
The anterior branch of the right hepatic duct is formed from the ducts of segments V and VIII; the posterior branch of the right hepatic duct - from the ducts of segments VI and VII; the lateral branch of the left hepatic duct is from the ducts of segments II and III. The ducts of the quadrate lobe of the liver flow into the medial branch of the left hepatic duct - the duct of the IV segment, and the right and left ducts of the caudate lobe, the ducts of the I segment can flow together or separately into the right, left and common hepatic ducts, as well as into the posterior branch of the right and into the lateral branch left hepatic duct. There may be other options for connecting segmental ducts I-VIII. The ducts of segments III and IV are often connected.
The right and left hepatic ducts at the anterior edge of the porta hepatis or already in the hepatoduodenal ligament form the common hepatic duct, ductus hepaticus communis.
The right and left hepatic ducts and their segmental branches are not permanent structures; if they are absent, then the ducts forming them flow into the common hepatic duct. The length of the common hepatic duct is 4-5 cm, its diameter is 4-5 cm. Its mucous membrane is smooth and does not form folds.
Topography of the liver.
Topography of the liver. The liver is located in the right hypochondrium, in the epigastric region and partially in the left hypochondrium. Skeletotopically, the liver is determined by its projection onto the chest walls. On the right and in front along the midclavicular line, the highest point of the liver (right lobe) is determined at the level of the fourth intercostal space; to the left of the sternum, the highest point (left lobe) is at the level of the fifth intercostal space. The lower edge of the liver on the right along the mid-axillary line is determined at the level of the tenth intercostal space; further forward the lower border of the liver follows the right half of the costal arch. At the level of the right midclavicular line, it emerges from under the arch, goes from right to left and upward, crossing the epigastric region. The lower edge of the liver crosses the linea alba of the abdomen halfway between the xiphoid process and the umbilical ring. Further, at the level of VIII of the left costal cartilage, the lower border of the left lobe crosses the costal arch to meet the upper border to the left of the sternum.
On the back right, along the scapular line, the border of the liver is defined between the seventh intercostal space (or VIII rib) at the top and top edge XI ribs below.
Liver syntopy. At the top, the upper part of the diaphragmatic surface of the liver is adjacent to the right and partially to the left dome of the diaphragm; in front of it, the anterior part is adjacent in sequence to the costal part of the diaphragm and to the anterior abdominal wall: behind the liver is adjacent to the X and XI thoracic vertebrae and legs of the diaphragm, the abdominal esophagus, and the aorta and to the right adrenal gland. The visceral surface of the liver is adjacent to the cardiac part, the body and pylorus of the stomach, the upper part of the duodenum, the right kidney, the right flexure of the colon and the right end of the transverse colon. The gallbladder is also adjacent to the internal surface of the right lobe of the liver.
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Lobes, sectors and segments of the liver
Left dorsal sector, corresponding to the first (CI) hepatic segment, includes the caudate lobe and is visible only on the visceral surface and posterior part of the liver.
Left lateral sector(II segment - CII) covers the posterior portion of the left lobe of the liver.
Left paramedian sector occupies the anterior part of the left lobe of the liver (III segment - CIII) and its quadrate lobe (IV segment - CIV) with a section of parenchyma on the diaphragmatic surface of the organ in the form of a strip tapering posteriorly (towards the groove of the inferior vena cava).
Right paramedian sector is a hepatic parenchyma bordering the left lobe of the liver. This sector includes segment V (CV), which occupies the posteromedial part of the right lobe of the liver on its diaphragmatic surface.
Right lateral sector, corresponding to the most lateral part of the right lobe of the liver, includes VI-CVI (lies in front) and VII-CVI segments. The latter is located behind the previous one and occupies the posterolateral part of the diaphragmatic surface of the right lobe of the liver.
Layers of connective tissue extend from the fibrous capsule deep into the liver, dividing the parenchyma into lobules, which are the structural and functional units of the liver.
The liver lobule (lobulus hepatis) has a prismatic shape, its diameter is 1.0-1.5 mm. The total number of lobules is approximately 500 thousand. The lobule is built from radially converging cell rows from the periphery to the center - hepatic beams. Each beam consists of two rows of liver cells - hepatocytes. Between the two rows of cells within the hepatic beam are the initial sections of the biliary tract (bile duct, ductulus bilifer). Between the beams, blood capillaries (sinusoids) are located radially, which converge from the periphery of the lobule to its central vein (v.centralis), located in the center of the lobule. There is a perisinusoidal space between the wall of the sinus capillary and hepatocytes (Disse). Between the lobules there is a small amount of connective tissue, in the thickness of which interlobular bile ducts, arteries and veins are located. Interlobular ducts, artery and vein are located nearby, forming the so-called hepatic triad. Thanks to this design, hepatocytes secrete in two directions: into the bile ducts - bile, into the blood capillaries - glucose, urea, fats, vitamins, etc., which enter the liver cells from the bloodstream or are formed in these cells.
Hepatocytes have a polygonal shape, their diameter is 20-25 microns. Most hepatocytes have one nucleus, a minority have two or more nuclei. The cytoplasm of the hepatocyte looks large or finely meshed, depending on the severity and composition of the inclusions (lipids, pigments). Hepatocytes have many mitochondria, pronounced endoplasmic reticulum and the Golgi complex, a significant number of ribosomes, lysosomes, as well as microbodies with products of fatty acid metabolism. There are many glycogen grains in the cytoplasm. The cytolemma of hepatocytes has numerous microvilli facing the perisinusoidal space, towards the blood capillaries.
The bile ducts originate from the intrahepatic lobules.
The liver lobules contain bile ducts, or canaliculi. The lumen (diameter) of the bile ducts is 0.5-1 microns. They do not have their own walls, since they are expanded zones of intercellular gaps between the rows of hepatocytes that make up the hepatic beam. Bile ducts have short blind branches (intermediate tubules of Hering), extending between adjacent hepatocytes, forming the walls of the bile ducts. Bile ducts (canaliculi) begin blindly near the central vein and go to the periphery of the lobule, where they open into interlobular (around lobular) bile ducts (ductuli interlobulares). The interlobular ducts connect with each other, increase in diameter, and form the right and left hepatic ducts (ductus hepaticus dexter et sinister). At the porta hepatis, these two ducts unite into the common hepatic duct, 4-6 cm long. Between the layers of the hepatoduodenal ligament, the common hepatic duct connects with the cystic duct (duct of the gallbladder) and forms the common bile duct.
The common bile duct (ductus choledochus, s.biliaris) is located between the layers of the hepatoduodenal ligament, anterior to the portal vein and to the right of the proper hepatic artery. Next, the common bile duct runs behind the upper part of the duodenum, then between its descending part and the head of the pancreas. In the wall of the duodenum, the common bile duct connects with the pancreatic duct and together with it forms an extension - the hepatopancreatic ampulla (ampulla hepatopancreatica). The ampulla opens into the duodenum at the apex of its major papilla. In the walls of the mouth of the hepatopancreatic ampulla there is a thickening of circular bundles of myocytes that form the sphincter of the hepatopancreatic ampulla, or sphincter of Oddi. The distribution of circular smooth muscle bundles of this sphincter is uneven. Smooth muscle bundles are most concentrated at the base of the major papilla and have a thickness of up to 75 microns, in the thickness of the nipple itself - 40 microns. The length of the sphincter is 15-20 microns.
During the period between food digestion processes, the sphincter of Oddi is closed, bile accumulates in the gallbladder, where it is concentrated. During the digestion process, the sphincter of Oddi opens and bile enters the duodenum.
There is also a sphincter in the walls of the terminal part of the common bile duct before its merger with the pancreatic duct. This sphincter of the common bile duct, when contracted, blocks the flow of bile from the biliary tract into the hepatopancreatic ampulla and further into the duodenum.
The walls of the interlobular bile ducts are formed by single-layer cuboidal epithelium. The walls of the hepatic, cystic and common bile ducts have three membranes. The mucous membrane is lined with single-layer high prismatic epithelium. The epithelium also contains goblet cells. The lamina propria of the mucous membrane is well developed, contains many longitudinal and circular elastic fibers, and a few multicellular mucous glands. The submucosa is poorly developed. The muscular layer is thin, consists mainly of spiral bundles of smooth myocytes, between which there is connective tissue.
Innervation of the liver
The liver is innervated by the branches of the vagus nerves and the hepatic (sympathetic) plexus.
Blood supply to the liver
The gates of the liver include the proper hepatic artery and the portal vein. The artery carries arterial blood, the portal vein carries venous blood from the stomach, pancreas, intestines, and spleen. Inside the liver, the artery and portal vein branch to the interlobular arteries and interlobular veins, which are located along with the bile interlobular ducts between the lobules of the liver. From the interlobular veins, wide blood capillaries (sinusoids) extend into the lobules and flow into the central vein. Arterial capillaries extending from the interlobular arteries flow into the initial sections of the sinusoids. The central veins of the hepatic lobules are connected to each other, forming sublobular (collecting) veins. The sublobular veins merge with each other, enlarge, and ultimately 2-3 hepatic veins are formed. They leave the liver in the area of the groove of the inferior vena cava and flow into this vein.
Lymph outflow: into the hepatic, celiac, right lumbar, upper diaphragmatic, parasternal lymph nodes.
Age-related features of the liver
In a newborn, the liver is large and occupies more than half the volume of the abdominal cavity. The weight of the liver in a newborn is 135 g, which is 4.0-4.5% of body weight (in adults 2-3%). The diaphragmatic surface of the liver is convex, the left lobe of the liver is equal in size to the right or larger. The lower edge of the liver is convex, located under its left lobe colon. The upper border of the liver along the right midclavicular line is at the level of the 5th rib, and along the left - at the level of the 6th rib. The left lobe of the liver crosses the costal arch along the left midclavicular line. The transverse size of the liver in a newborn is 11 cm, longitudinal - 7 cm, vertical - 8 cm. In a 3-4 month old child, the intersection of the costal arch with the left lobe of the liver, due to a decrease in its size, is already on the parasternal line. In newborns, the lower edge of the liver along the right midclavicular line protrudes from under the costal arch by 2.5-4.0 cm, and along the anterior midline - by 3.5-4.0 cm below the xiphoid process.
Sometimes the lower edge of the liver reaches the right wing ilium. In children 3-7 years old, the lower edge of the liver is 1.5-2.0 cm below the costal arch (along the midclavicular line). In a 7-year-old child, the weight of the liver reaches 700 g. After 7 years, the lower edge of the liver does not protrude from under the costal arch; Only the stomach is located under the liver. From this time on, the skeletotopy of the child’s liver is almost no different from the skeletotopy of an adult. In children, the liver is very mobile, and its position easily changes with changes in body position. The liver reaches its final size after 20-29 years. After 60-70 years, the weight of the liver decreases, its connective tissue grows. In hepatocytes with age, the amount of lipofuscin increases, the number of dividing hepatocytes sharply decreases, and the size of their nuclei increases.
Hepar, the largest of the digestive glands, occupies the upper abdominal cavity, located under the diaphragm, mainly on the right side.
By shape liver somewhat resembles the cap of a large mushroom, has an upper convex and lower slightly concave surface. However, the convexity is devoid of symmetry, since the most protruding and voluminous part is not the central part, but the right rear one, which tapers anteriorly and to the left in a wedge-shaped manner. Human liver dimensions: from right to left on average 26-30 cm, from front to back - right lobe 20-22 cm, left lobe 15-16 cm, greatest thickness (right lobe) - 6-9 cm. The weight of the liver is on average 1500 g. Its color is red -brown, soft consistency.
Structure human liver: there is a convex upper diaphragmatic surface, facies diaphragmatica, a lower, sometimes concave, visceral surface, facies visceralis, a sharp lower edge, margo inferior, separating the upper and lower surfaces in front, and a slightly convex rear part, pars posterior. diaphragmatic surface.
On the lower edge of the liver there is a notch of the round ligament, incisura ligaments teretis: to the right there is a small notch corresponding to the adjacent bottom of the gallbladder.
The diaphragmatic surface, facies diaphragmatica, is convex and corresponds in shape to the dome of the diaphragm. From the highest point there is a gentle slope to the lower sharp edge and to the left, to the left edge of the liver; a steep slope follows to the posterior and right parts of the diaphragmatic surface. Upwards, to the diaphragm, there is a sagittally located peritoneal falciform ligament of the liver, lig. falciforme hepatis, which follows from the lower edge of the liver back for about 2/3 of the width of the liver: behind the leaves of the ligament diverge to the right and left, passing into the coronary ligament of the liver, lig. coronarium hepatis. The falciform ligament divides the liver, according to its upper surface, into two parts - the right lobe of the liver, lobus hepatis dexter, which is large and has the greatest thickness, and the left lobe of the liver, lobus hepatis sinister, which is smaller. On the upper part of the liver one can see a small cardiac depression, impressio cardiaca, formed as a result of the pressure of the heart and corresponding to the tendon center of the diaphragm.
On the diaphragm liver surface distinguish the upper part, pars superior, facing the tendon center of the diaphragm; the anterior part, pars anterior, facing anteriorly, to the costal part of the diaphragm, and to the anterior wall of the abdomen in the epigastric region (left lobe); the right part, pars dextra, directed to the right, towards the lateral abdominal wall (corresponding to the mid-axillary line), and the back part, pars posterior, facing towards the back.
The visceral surface, facies visceralis, is flat, slightly concave, corresponding to the configuration of the underlying organs. There are three grooves on it, dividing this surface into four lobes. Two grooves have a sagittal direction and stretch almost parallel to one another from the anterior to the posterior edge of the liver; approximately in the middle of this distance they are connected, as if in the form of a crossbar, by a third, transverse, furrow.
The left sulcus consists of two sections: the anterior, extending to the level of the transverse sulcus, and the posterior, located posterior to the transverse. The deeper anterior section is the fissure of the round ligament, fissura lig. teretis (in the embryonic period - the groove of the umbilical vein), begins on the lower edge of the liver from the notch of the round ligament, incisura lig. teretis. it contains the round ligament of the liver, lig. teres hepatis, running in front and below the navel and enclosing the obliterated umbilical vein. The posterior part of the left groove is the fissure of the venous ligament, fissura lig. venosi (in the embryonic period - fossa ductus venosi, fossa ductus venosi), contains the venous ligament, lig. venosum (obliterated ductus venosus), and stretches from the transverse groove back to the left hepatic vein. The left groove, in its position on the visceral surface, corresponds to the line of attachment of the falciform ligament on the diaphragmatic surface of the liver and, thus, serves here as the boundary of the left and right lobes of the liver. At the same time, the round ligament of the liver is located in the lower edge of the falciform ligament, on its free anterior section.
The right groove is a longitudinally located fossa and is called the gallbladder fossa, fossa vesicae felleae, which corresponds to a notch on the lower edge of the liver. It is less deep than the groove of the round ligament, but wider and represents the imprint of the gallbladder located in it, vesica fellea. The fossa extends posteriorly to the transverse groove; its continuation posterior to the transverse groove is the groove of the inferior vena cava, sulcus venae cavae inferioris.
The transverse groove is the gate of the liver, porta hepatis. It contains the own hepatic artery, a. hepatis propria, common hepatic duct, ductus hepaticus communis, and portal vein, v. portae.
Both artery and vein are divided into main branches, right and left, already at the hilum liver.
These three grooves divide the visceral surface of the liver into four lobes of the liver, lobi hepatis. The left groove delimits the lower surface of the left lobe of the liver to the right; the right groove demarcates on the left the lower surface of the right lobe of the liver.
The middle area between the right and left grooves on the visceral surface of the liver is divided by a transverse groove into anterior and posterior. The anterior portion is the quadrate lobe, lobus quadratus, and the posterior portion is the caudate lobe, lobus caudatus.
On the visceral surface of the right lobe of the liver, closer to the anterior edge, there is a colonic depression, impressio colica; behind, to the very rear edge, there are: to the right - a large depression from the right kidney adjacent here, the renal depression, impressio renalis, to the left - the duodenal (duodenal) depression, impressionio duodenalis, adjacent to the right groove; even more posteriorly, to the left of the renal depression, - depression of the right adrenal gland, adrenal depression, impressio suprarenalis.
The square lobe of the liver, lobus quadratus hepatis, is bounded on the right by the fossa, on the left by the fissure of the round ligament, in front by the lower edge, and behind by the porta hepatis. In the middle of the width of the square lobe there is a depression in the form of a wide transverse groove - an imprint of the upper part, a duodenal indentation that continues here from the right lobe of the liver.
The caudate lobe of the liver, lobus caudatus hepatis, is located posterior to the portal of the liver, limited in front by the transverse groove of the portal of the liver, on the right - by the groove of the vena cava, sulcus venae cavae, on the left - by the fissure of the venous ligament, fissura lig. venosi, and behind - the posterior part of the diaphragmatic surface of the liver. On the anterior section of the caudate lobe on the left there is a small protrusion - the papillary process, processus papillaris, adjacent to the back of the left part of the porta hepatis; on the right, the caudate lobe forms the caudate process, processus caudatus, which goes to the right, forms a bridge between the posterior end of the gallbladder fossa and the anterior end of the groove of the inferior vena cava and passes into the right lobe of the liver.
The left lobe of the liver, lobus hepatis sinister, on the visceral surface, closer to the anterior edge, has a convexity - the omental tubercle, tuber omentale, which faces the lesser omentum, omentum minus. On the posterior edge of the left lobe, immediately next to the fissure of the venous ligament, there is a depression from the adjacent abdominal part of the esophagus - the esophageal depression, impressio esophageale.
To the left of these formations, closer to the back, on the lower surface of the left lobe there is a gastric impression, impressio gastrica.
The posterior part of the diaphragmatic surface, pars posterior faciei diaphragmaticae, is a rather wide, slightly rounded section of the surface of the liver. It forms a concavity corresponding to the place of contact with the spine. Its central section is wide, and narrows to the right and left. Corresponding to the right lobe there is a groove in which the inferior vena cava is located - the groove of the vena cava, sulcus venae cavae. Closer to the upper end of this groove in the substance of the liver, three hepatic veins, venae hepaticae, are visible, flowing into the inferior vena cava. The edges of the groove of the vena cava are connected to each other by the connective tissue ligament of the inferior vena cava.
The liver is almost completely surrounded by the peritoneum. The serous membrane, tunica serosa, covers its diaphragmatic, visceral surfaces and lower edge. However, in places where the ligaments approach the liver and the gallbladder is adjacent, there remain areas of varying widths that are not covered by the peritoneum. The largest area not covered by peritoneum is on the posterior part of the diaphragmatic surface, where the liver is directly adjacent to the posterior wall of the abdomen; it has the shape of a rhombus - extraperitoneal field, area nuda. Corresponding to its greatest width, the inferior vena cava is located. The second such area is located at the location of the gallbladder. The peritoneal ligaments extend from the diaphragmatic and visceral surfaces of the liver.
The structure of the liver.
The serous membrane, tunica serosa, covering the liver, is underlain by the subserosal base, tela subserosa, and then by the fibrous membrane, tunica fibrosa. Through the portal of the liver and the posterior end of the gap of the round ligament, together with the vessels, connective tissue penetrates into the parenchyma in the form of the so-called perivascular fibrous capsule, capsula fibrosa perivascularis, in the processes of which are located the branches of the portal vein and the proper hepatic artery; along the course of the vessels it reaches the fibrous membrane from the inside. This is how a connective tissue frame is formed, in the cells of which the liver lobules are located.
Liver lobule.
Liver lobule, lobulus hepaticus, 1-2 mm in size. consists of liver cells - hepatocytes, hepatocyti, forming liver plates, laminae hepaticae. In the center of the lobule is the central vein, v. centralis, and around the lobule there are interlobular arteries and veins, aa. interlobular et vv, interlobulares, from which interlobular capillaries originate, vasa capillaria interlobularia. Interlobular capillaries enter the lobule and pass into sinusoidal vessels, vasa sinusoidea, located between the hepatic plates. In these vessels arterial and venous (from v, portae) blood mixes. The sinusoid vessels empty into the central vein. Each central vein joins the sublobular, or collecting, veins, vv. sublobulares, and the latter - into the right, middle and left hepatic veins. vv. hepaticae dextrae, mediae et sinistrae.
Between the hepatocytes lie bile canaliculi, canaliculi biliferi, which flow into the ductuli biliferi, and the latter, outside the lobules, connect into the ductus interlobulares biliferi. Segmental ducts are formed from the interlobular bile ducts.
Based on the study of intrahepatic vessels and bile ducts, a modern understanding of the lobes, sectors and segments of the liver has emerged. The branches of the portal vein of the first order bring blood to the right and left lobes of the liver, the border between which does not correspond to the external border, but passes through the fossa of the gallbladder and the groove of the inferior vena cava.
Second-order branches provide blood flow to the sectors: in the right lobe - to the right pyramidal sector, sector paramedianum dexter, and the right lateral sector, sector lateralis dexter; in the left lobe - into the left paramedian sector, sector paramedianum sinister, the left lateral sector, sector lateralis sinister, and the left dorsal sector, sector dorsalis sinister. The last two sectors correspond to liver segments I and II. The other sectors are each divided into two segments, so that there are 4 segments in the right and left lobes.
The lobes and segments of the liver have their own bile ducts, branches of the portal vein and their own hepatic artery. The right lobe of the liver is drained by the right hepatic duct, ductus hepaticus dexter, which has anterior and posterior branches, r. anterior et r. posterior, the left lobe of the liver - the left hepatic duct, ductus hepaticus sinister, consisting of medial and lateral branches, r. medialis et lateralis, and the caudate lobe - by the right and left ducts of the caudate lobe, ductus lobi caudati dexter et ductus lobi caudati sinister.
The anterior branch of the right hepatic duct is formed from the ducts of segments V and VIII; the posterior branch of the right hepatic duct - from the ducts of segments VI and VII; the lateral branch of the left hepatic duct is from the ducts of segments II and III. The ducts of the quadrate lobe of the liver flow into the medial branch of the left hepatic duct - the duct of the IV segment, and the right and left ducts of the caudate lobe, the ducts of the I segment can flow together or separately into the right, left and common hepatic ducts, as well as into the posterior branch of the right and into the lateral branch left hepatic duct. There may be other options for connecting segmental ducts I-VIII. The ducts of segments III and IV are often connected.
The right and left hepatic ducts at the anterior edge of the porta hepatis or already in the hepatoduodenal ligament form the common hepatic duct, ductus hepaticus communis.
The right and left hepatic ducts and their segmental branches are not permanent structures; if they are absent, then the ducts forming them flow into the common hepatic duct. The length of the common hepatic duct is 4-5 cm, its diameter is 4-5 cm. Its mucous membrane is smooth and does not form folds.
Topography of the liver.
Topography of the liver. The liver is located in the right hypochondrium, in the epigastric region and partially in the left hypochondrium. Skeletotopically, the liver is determined by its projection onto the chest walls. On the right and in front along the midclavicular line, the highest point of the liver (right lobe) is determined at the level of the fourth intercostal space; to the left of the sternum, the highest point (left lobe) is at the level of the fifth intercostal space. The lower edge of the liver on the right along the mid-axillary line is determined at the level of the tenth intercostal space; further forward the lower border of the liver follows the right half of the costal arch. At the level of the right midclavicular line, it emerges from under the arch, goes from right to left and upward, crossing the epigastric region. The lower edge of the liver crosses the linea alba of the abdomen halfway between the xiphoid process and the umbilical ring. Further, at the level of VIII of the left costal cartilage, the lower border of the left lobe crosses the costal arch to meet the upper border to the left of the sternum.
Colon. It is also adjacent to the internal surface of the right lobe of the liver.
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