Anatomy of the liver and biliary tracts

Macroscopic structure of the liver is well known and therefore omitted in this section.
The conception of the microscopic structure of the liver recently significantly refined.
Electron microscopic and entomologicheskie research made it possible to connect many functions of cells with defined its structural units - organelles.
All of the most important cellular structures built by membrane-granular basis. To the surface of membranes permanently or temporarily attached certain enzymes. Membranes have special physical value. They regulate the activity of enzymes and interaction of intracellular enzymes with the substrate, provide the processes of synthesis in the cell, while preserving the specific features of cells.
The main cell element of the liver are epithelial cells - hepatocytes.
The structure of hepatocytes provides multiple functions: absorption, participation in interstitial exchange, accumulation of various substances, secretion and excretion. This corresponds to an abundance zitoplazmaticakih organelles and specialization of separate parts of the cell membranes.
In hepatic cell distinguish the shell, the cytoplasm, carrying the organelles, and the kernel with nucleoli (Fig. 48).

Fig. 48. The scheme of the hepatocyte ultrastructure, kuperovskaya cells and epithelial cells of bile ducts (by A. F. Bluhera, 1964).
I hepatocyte; II - kuperovskaya cell; III - related hepatocyte; IV - cell bile duct. 1 - nucleus; 2 - core; 3 - the mitochondria; For - elementary particles; 4 - complementary mechanism; 5 - tank protein; 6 - a drop of fat; 7 - endoplasmic network; 7a - grain glycogen; 8 - endoplasmic network (granular); 9 - ribosome; 10 - perebrannye bullock; 11 - Golgi apparatus; 12 - gall capillary fibers; 13 - desmosome; 14 - shell nuclei; 15 - microbikini; 16 - border kuperovskaya cells; 17 - the space of the thesis; 18 - vacuoles.

In hepatocytes secrete two poles - sinusoidal and biliary. First converted to a sine wave, which is reported through the so-called presinusoidal gap (the space of the RICS), located between the lung and endothelial cells. Here is the absorption of various metabolites. On biliary pole cell has a "deepening" of the plasma membrane, which, together with similar "deepening" of neighboring hepatocytes forms gall capillary, where the excretion of bile and other substances. These poles hepatocytes equipped with fringed protrusions cytoplasm - microvilli, which significantly increases the surface of cells. The migration of substances occurs not only between listed and biliary poles, but also between the kernel and sinusoidal pole of the cell.
The core of the hepatocyte person has a diameter of about 8 m, it is surrounded by a double membrane. The outer shell of the nucleus is connected with the endoplasmic network of cells. Nucleoplasm consists predominantly of DNA considered by gistologii as chromatin. After puberty in humans in the liver along with diploid nuclei can be found tetraploid, and after the age of 20 - and octaploid. The growth of pripodnesti nuclei is considered precyclone state. In the chromatin network concluded 1-2 basophilic nucleolus containing grain RNA.
The main substance of the cytoplasm (the matrix) consists of proteins and surrounds all the other components of cytoplasm. In the hepatocyte cytoplasm visible rich endoplasmic network of system convoluted tubule, often grouped in bunches. There are granular endoplasmic network (elastoplast) and smooth endoplasmic network. The grit elastoplast formed by clusters of ribonucleoproteins (ribosomes) on the surface of membranes. Ribosomes are considered as the place of protein synthesis.
Smooth endoplasmic network free of ribosomes and, apparently, plays a significant role in glycogenesis, glycogenolysis, and in cholesterol metabolism, is the place of formation of bilious acids, conjugation of bilirubin, synthesis of steroids; participates in the removal of many substances, including drugs. In endoplasmic reticulum is most specific for liver cells functions. The energy required to do this, accumulated by mitochondria, which in hepatocyte contains more than 1000. They have a double membrane, which is based on lipid molecules, covered protein particles. The outer membrane smooth, and the internal forms webbed folds - Christa. The space between them filled in the basic substance - matrix, consisting of protein.
In mitochondria runs a large amount of energy processes, mainly oxidative phosphorylation. They contain a lot of phospholipids, enzymes electron-transport system ("respiratory chain") and can oxidize many substrates, including fatty acids and intermediate products of the Krebs cycle. The energy released by the mitochondria can be transformed into high-energy vospitanie communication ATP.
The biliary pole liver cells are visible so-called perebrannye patterns: a tight little body, microtelco and complementary mechanism. Last contain many enzymes active at acidic pH, particularly acid phosphatase. The pathological conditions of these enzymes can be freed and destroy the cell. The function of lysosomes is diverse: the digestion of insoluble substances, destruction of organelles with a short lifetime, the accumulation of various materials (ferritin, lipofuscin, bile pigment, copper etc). About biliary pole is located and the Golgi apparatus, consisting of a system of particles and bubbles built from pagkakataong membranes. It is functionally connected with the excretory activity of hepatocytes, in particular with excretion of bile. The whole group: complementary mechanism, microtelco, the Golgi apparatus can be considered as a tool for isolating any of absorbed material that must be secreted or excreted or should be accumulated for metabolic processes in the cytoplasm. In addition, the cytoplasm contains various include: lipids, glycogen, protein secretion and pigment granules. The nature of these inclusions depends on the power and level of exchange processes. The endothelial cells of sinusoidal liver (kuperovskaya cells) are considerable variability. They are oblong education serrated kernel and a small rim of cytoplasm, carrier few mitochondria and different number of lysosomes. They are often seen phagocytary material.
Endothelial cells produce argyrophile fiber than steadying fibrous structures forming reticulosis backbone of the liver (Century, Orel, 1960). In pathological conditions endothelial cells proliferate and can be transformed into macrophages, fibroblasts (Popper, Schaffner, 1965; A. F. of Bluger and others, 1970).
According to the settled opinion, liver consists of many small units - slices. Last is formed by a series of liver cells - of trabeculae, radially converging to Central Vienna. Beams consist of two layers of cells, among which are the gall capillaries. Between the beams are the sine - capillary bed, which circulates the blood that washes liver cells. On the periphery of the segments are the so-called portal tracts, or the portal of the field. They are clusters of connective tissue, of which originate lattice, or reticulose, fiber, connective tissue forming the backbone of the liver. In the portal fields are magdalsophia branching portal vein and hepatic artery, and magdalsophia bile ducts (the so-called "portal triad" - Fig. 49).

Fig. 49. Histological pattern hepatic lobules.
1 - branches of the hepatic artery; 2 - biliary tract; 3 - portal tracts; 4 - trabeculae liver cells; 5 - Central Vienna; 6 - magdalsophia branching portal vein.

Elias (1949, 1954, 1956), who studied the serial slices through the liver, created a solid model. According to Elias, the basis of the structure of the liver are liver plates consisting of one row of cells, They delimit cylindrical blood space - gaps related to each other numerous anastomoses. The result is a so-called hepatic labyrinth (Fig. 50). Under normal pressure in the portal and Central veins these space converge to a lacuna, embodying the portal vein. Channel portal vein is surrounded by a bounding plate, whose cells are smaller than normal hepatic and more basophils. Limiting the album is penetrated by blood vessels leading to the parenchyma (septal branches of veins and arteries) and nutrical uniform hyangilam flowing into the bile duct (Fig. 51).

Fig. 50. Hepatic maze for Elias.
Explanation in the text.
Fig. 51. Stereometric scheme normal liver (Elias).
And - branch of the hepatic artery; (D - gall course; VP - portal vein; V - the branch of the portal vein; P - liver cell; L - the guide plate.

The stability of the structure of the liver primarily ensured by connecting the skeleton of the liver. It was founded retikuluma, or lattice, fibers, and derived from connective tissue capsule portal channels. Longitudinal fibers form the basis of sinusoidal. They are moving away so called twisted fibers, surrounding the hepatocytes. Reticulin fibers have complex colloidal structure, easily changing depending on conditions. In addition to the connective tissue framework of the stability of the liver structure due turgor of liver cells, blood vessels and biliary tract.
The liver has a unique system of blood circulation, as it gets the blood through two vascular system: the portal vein and hepatic artery. The outflow of blood is via hepatic vein. Portal vein flow the bulk of blood flowing from the abdominal organs. The blood from the distal intestine comes in through the portal vein of the inferior mesenteric vein (v. mesenterica inferior). Last flows into the splenic vein (v. lienalis) or directly into the main trunk of the portal vein. Superior mesenteric vein (v. mesenterica superior), at which blood flowing from the rest of the intestine and partly from the stomach, connecting with splenic vein, forms the trunk of the portal vein. Here poured coronary Vienna stomach (v. coronaria ventriculi). Splenic vein through the fabric of the spleen takes a short Vienna stomach, and sometimes coronary vein. These veins anastomose with each other, forming a fistula between the portal vein and the inferior Vena veins.
There are three groups of natural Porto kafelnyh anastomoses:
1) in the area pryamokishechnye venous plexus - through the inferior mesenteric vein and pryamokishechnye Vienna;
2) in the zone of esophago-gastric plexus - through the splenic vein, sometimes flowing into it coronary veins of the stomach, esophageal plexus and pollonarrua Vienna;
3) in the system paraumbilical veins, anastomosis with the veins of the abdominal wall and diaphragm.
In addition, there are anastomoses located and retroperitoneal fat: a) between the mesenteric veins and kidneys; b) upper mesenteric vein through the splenic with pronephros Vienna and in between the splenic and left renal vein.
These natural Porto kavalenya anastomoses are of great importance for compensation circulation disorder in the system of portal vein.
The barrel of the portal vein, located dorsal to the head of the pancreas liver-duodenal sheaf, comes to the gates of the liver, which is divided into two main branches, heading to the respective shares of the liver. In the future, these branches are divided up twigs 6-th and 7-th order. Branch of the portal vein, hepatic artery and gall ways pass right in the portal channels (see Fig. 51). Their end branches penetrate through restrictive record and included in the liver parenchyma. End magdalsophia branching portal vein, extending, form a sine wave, from which the blood is collected in Central Vienna and then in the liver. Arterioles hepatic artery branches are connected with a portal veins and sinuses.
Thus, in the system of hepatic blood circulation is activated arterial blood.
Wall sinusoidal consists of syncytium endothelial cells, however, the latter do not form a continuous layer, and between them there are cracks. Unlike blood capillaries other bodies of the liver sinusoids not have the basal membrane. Thus, sinusoidal surface of hepatocytes through space the Diss is washed directly blood plasma (NoviKoff. Essner, 1960; Pnillips, 1968).
Vnutritrekovye arterioles and venules, at the confluence them in sinusoid is equipped with the sphincters. Thanks to the action of these sphincter sine wave may be dominated or portal (venous), or arterial blood, depending on the status of metabolism in the moment, and first of all depending on the needs of the liver in oxygen. Under physiological conditions operates only a quarter of all sinusoidal, the remaining 3/4 isolated from the effective circulation. This is a large reserve capacity of the liver in the regulation of the latter.
Intrahepatic branches of the hepatic artery, the portal and hepatic veins braided lymphatic vessels. Lymphatic vessels are lying in the portal tracts lead to lymph nodes in the gate of the liver. Through the lymphatic vessels, surrounding the hepatic veins, lymph enters the lymph nodes located near the Vena cava. Lymphatic vessels within the segments not identified (D. A. Zhdanov, 1962).
Gall capillaries located between the plates of liver cells that give rise to a system of ducts. Wall they formed part of cytoplasm of liver cells. In the zone, which is lined with capillary, cytoplasm thickened and has microbikini acting in the lumen of the bile capillary. Lumen gall capillaries not greater than 1 micron in diameter and because of the small size can easily be blocked fibers and gall clots. Using an electron microscope, the possibility of direct communication between the gall capillaries and the spaces of the thesis (Kouiller, 1957; Popper, 1960). Gall capillaries located between liver slices, go into the capillaries of the bounding plate. Last through the narrow passage lined cubic epithelium ("inserted", channels of Goering or cholangio), connected with bile passages located in the portal tracts.
For all ukrupnenie bilious channels bile comes in intrahepatic bile ducts. The walls have their fibrous membrane, poor smooth muscle fibers and mucous membrane lined single cubic epithelium. These ducts, gradually merging, form the right and left hepatic ducts (dd. hepatici), which is usually already outside the liver meet in the common hepatic duct. From the specified duct 3 cm below the gate liver branches off cystic duct (d. cysticus). The further part of the common bile duct (d. choledochus) - next to the hepatic artery and portal vein takes place in the liver-duodenal sheaf near the pancreatic head and sometimes through its fabric, the inside wall of the descending part of the duodenum. Here it is opened in the last gleam along or near the outlet duct pancreas. When passing through the wall of the intestine lumen of the common bile duct forms spindle extension, lying under the intestine mucous, - paterova ampoule. In the place where the vial is opened in the gut, a small protrusion of its walls, the so-called Tatarov nipple (papilla Vateri.) It is a ring of muscle pulp - sphincter of Oddi, which is the most powerful muscle education on the path of bile. The gallbladder is adjacent to the lower surface of the liver in the so-called gallbladder fossa. Its body is covered abdominal cover, shared with the liver, and is connected with the last loose connective tissue small vascular branches and lymph vessels. The bottom it stands out from under the front edge of the liver and is adjacent to the anterior abdominal wall approximately respectively the intersection of the outer edge of the right rectus and right costal arch. The neck of the bladder facing backwards and upwards, it departs cystic duct. He is held in the thickness of the liver-duodenal sheaf and flows into the common hepatic duct. At the junction of the cervix in cystic duct muscle layer few hypertrophies, and fiber it sent a circular - sphincter of Ludens. The mucosa of the bladder are lined with tall cylindrical epithelium, rich folds and forms a narrow introduction into the muscle layer of the so-called moves Rokitanskйho - Asifa. In proximal part of the cystic duct mucous forms several spiral folds that can close a significant part of its clearance, the so - called valves Geister (valvulae Heisteri, Fig. 52).

Fig. 52. The scheme of the biliary tract.
1 - gall bladder; 2 - cystic duct and valves of Gaster; 3 - hepatic duct; 4 - the common bile duct; 5 - pancreatic duct; 6 - Federov papilla.

The capacity of the gallbladder equal 30-70 ml, but he concentrates hepatic bile in 5-10 times or more. The movement of bile in a gall ways is due to three main factors: secretory pressure bile, which can reach 30 cm of water. century; the contractile force of the gallbladder; reductions (peristaltic) sphincter of Oddi. Famous role plays and valve-sphincter system cervical gallbladder.
Innervation of the liver is left branch of the vagus nerve fibers of the sympathetic nerve, coming from the solar plexus. Sympathetic fibers entwine predominantly hepatic artery and its ramifications, at the same time parasympathetic accompany the ramifications of the portal vein. Vnutriportovaya innervation studied enough. In the liver parenchyma contains a lot of nerve fibers running along hepatic plates between the walls of capillaries and liver cells and forming a closed network. These fibres end bulges and function as receptors (C. M. Godunov, 1962).
Regulation of functions of the biliary system is humoral way and nervous system. Along with involvement of the Central nervous system the parasympathetic and sympathetic nerves, in the regulation of the essential role of private nerve ganglia, lying in the walls of the extrahepatic bile duct. The vagus nerve enhances muscle tone of the gallbladder, the condition of the sphincter of Oddi depends on the irritation of the nerve. Sympathetic nerve reduces tone and gall bladder and sphincter of Oddi. Reflex regulation emptying of the biliary tract is made with the help of unconditional (particularly food), and the conditional irritants; therefore, it is under the control of the higher functions of the nervous system that is proved by the works of laboratories I. P. Pavlov and K. M. Bykov.
Ivi et al. (1934, 1937) showed that in the regulation of the motor function of the biliary tract is of great importance humoral mechanism. Upon receipt of fat in the duodenum mucous her and jejunum highlights in the blood hormones - secretin, cholecystokinin that cause contraction of the gallbladder and the disclosure of the sphincter of Oddi.
Due to the many reflex influences and complexity of the regulatory framework of the biliary tract motility is often violated, which is of great importance in pathology.

   The main pathological changes
Research methods
   Biochemical studies
   Instrumental investigations
Chronic hepatitis and liver cirrhosis
   Etiology
   Pathogenesis and morphogenesis
   Pathologic anatomy
   Classification
   Clinical symptomatology and for
Syndromes, aggravating for liver cirrhosis
      Portal hypertension
      Ascites
      Portosystemic encephalopathy
   Diagnosis
   Prevention
   Treatment
Liver abscess, parasitic diseases of the liver, liver tumors
   Liver abscess
Parasitic diseases
      Opisthorchiasis liver
      Echinococcosis of the liver
   Liver tumors
      Benign liver tumors
      Malignant tumors of the liver
Diseases of the biliary tract
   Cholecystitis, cholelithiasis
      The etiology and pathogenesis
      Pathologic anatomy
      Classification
      Clinical symptoms
      Forecast
      Prevention and treatment
Biliary dyskinesia