The Liver building
The

Liver

The liver is the largest gland in the body, taking part in the processes of metabolism, digestion , blood circulation and hematopoiesis.

Anatomy . The liver is located in the abdominal cavity under the diaphragm in the right upper quadrant, the epigastric region and reaches the left hypochondrium. It comes in contact with the esophagus , stomach, right kidney and adrenal gland, with the transverse colon and duodenum (Figure 1).

topography of the liver
Fig. 1. Topography of the liver: 1 - stomach; 2 - projection of the pancreas; 3 - duodenum; 4 - gall bladder; 5 - common bile duct; 6 - liver.
The

The liver consists of two parts: the right and left (Figure 2). On the lower surface of the liver are two longitudinal and transverse grooves - the gates of the liver. These furrows divide the right share into the right-handed, caudate and square shares. In the right sulcus there is a gallbladder and a lower hollow vein. The portal of the liver includes the portal vein, the hepatic artery, the nerves, and the hepatic bile duct and lymphatic vessels exit. The liver, with the exception of the posterior surface, is covered with the peritoneum and has a connective tissue capsule (glisson capsule).

structure of the liver
Fig. 2. The structure of the liver: (a - the lower surface, b - the upper surface): 1 - the lower hollow vein; 2 - portal standing from the hepatic vein; 3 - common bile duct; 4 - right lobe of the liver; 5 - bladder duct; 6 - gall bladder; 7 - hepatic duct; 8 - left lobe of the liver; 9 - ligament of the liver.

The hepatic lobule, consisting of liver cells constitutes the main structural unit of the liver. Hepatic cells are arranged in the form of strands, called hepatic beams. They are bile capillaries, the walls of which are hepatic cells, and between them - blood capillaries, the walls of which are formed by stellate (Kupffer) cells. In the center of the lobule passes the central vein. Hepatic lobes form the parenchyma of the liver. Between them in the connective tissue are interlobular arteries, vein and bile duct. The liver receives a double blood supply: from the hepatic artery and portal vein, (see). The outflow of blood occurs from the liver through the central veins, which, merging, flow into the hepatic veins opening into the lower vena cava. On the periphery of the lobules of the bile capillaries, interlobular bile ducts are formed, which, merging, form a hepatic duct in the gates of the liver, which removes bile from the liver. Hepatic, the duct connects to the vesicular duct and forms a common bile duct (bile duct) that flows into the duodenum through its large nipple (nipple pectora).

The

Physiology . Absorbed substances from the intestine into the blood through the portal vein enter the liver, where they undergo chemical changes. The involvement of the liver is proven in all kinds of metabolism (see Nitrogen Exchange, Bilirubin, Fat Exchange, Pigment Exchange , Carbohydrate Exchange ). The liver takes a direct part in the water-salt metabolism and in maintaining the consistency of the acid-base balance. In the liver, vitamins (groups B, C, groups D, E and K) are deposited. Of carotenes, vitamin A is formed in the liver.

The barrier function of the liver is to delay some toxic substances entering through the portal vein, and transfer them to harmless to the body connections. No less important is the function of the liver in the deposition of blood. Liver vessels can contain 20% of all blood circulating in the vascular bed.

The liver has a cholagogic function. Bile in its composition contains many substances circulating in the blood (bilirubin, hormones, medicinal substances), as well as bile acids, formed in the liver itself. Bile acids contribute to the retention in the dissolved state of a number of substances found in bile ( cholesterol , calcium salts, lecithin). Getting with bile in the intestine, they promote emulsification and absorption of fat. In the process of formation of bile, Kupffer's and hepatic cells take part. The process of bile formation is affected by humoral (peptone, salts of choleic acid, etc.), hormonal (adrenaline, thyroxine, ACTH, cortin, sex hormones ) and nerve factors.

The liver (hepar) - the largest gland in the human body, taking part in the processes of digestion, metabolism and circulation, carries out specific enzymatic and excretory functions.

Embryology
The liver develops from the epithelial protrusion of the midgut. At the end of the first month of intrauterine life, the hepatic diverticulum begins to differentiate into the cranial part, from which all the liver parenchyma, the central and caudal parts, which give rise to the gallbladder and bile ducts, are formed. The primary lining of the liver due to the intensive multiplication of cells is rapidly growing and is introduced into the mesenchyma of the ventral mesentery. Epithelial cells are arranged in rows, forming hepatic beams. Between the cells there are cracks - bile ducts, and between the beams from the mesenchyme blood tubes and the first uniform elements of blood are formed. The liver of the six-week-old embryo already has a glandular structure. Increasing in volume, it occupies the entire sub-diaphragm region of the fetus and spreads caudally to the lower floor of the abdominal cavity.