Human Anatomy and Physiology (with Age-Related Features of the Child's Body) - Sapin, M.R., & Sivoglazov, V.I. 2002

The Doctrine of the Viscera (Splanchnology)
Digestive System
Liver

The liver is the largest digestive gland in The Human Body, characterized by a soft consistency and a reddish-brown color. In an adult, the liver weighs approximately 1.5 kg.

The liver plays a key role in protein, carbohydrate, lipid, and vitamin METABOLISM. Among its numerous Functions, the protective and Bile-producing functions are particularly vital. During the prenatal period, the liver also acts as a hematopoietic organ.

The liver is situated in the Abdominal cavity just beneath the Diaphragm on the right side, occupying the right hypochondrium, with only a small portion extending left into the epigastric region. The anterosuperior (diaphragmatic) surface of the liver is convex, conforming to the concavity of the diaphragm. The anterior margin of the liver is sharp. The inferior (visceral) surface features several impressions formed by adjacent Organs.

The falciform ligament, consisting of two peritoneal folds extending from the diaphragm to the liver, divides the diaphragmatic surface into two lobes—a larger right lobe and a smaller left lobe. Two sagittal fissures and one transverse fissure, which serves as the porta hepatis (hepatic hilum), are visible on the visceral surface. Entering the porta hepatis are the portal vein, the proper hepatic artery, and nerves, while the common hepatic duct and Lymphatic vessels exit from it. In the anterior portion of the right sagittal groove, situated between the quadrate and proper right lobes, lies the Gallbladder, whereas its posterior part lodges the INFERIOR VENA CAVA. The anterior section of the left sagittal groove contains the round ligament of the liver (ligamentum teres hepatis), which represents the embryonic umbilical vein. The posterior segment of this groove houses the fibrous remnant of the ductus venosus, which in the fetus connected the umbilical vein to the inferior vena cava.

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Fig. 46. The liver. Visceral surface:

1 — common bile duct, 2 — cystic duct, 3 — gallbladder, 4 — right lobe, 5 — peritoneal fold, 6 — round ligament of the liver, 7 — quadrate lobe, 8 — left lobe, 9 — common hepatic duct, 10 — hepatic artery, 11 — portal vein, 12 — caudate lobe, 13 — inferior vena cava

The liver is enclosed by the Peritoneum on all sides, except for the posterior surface where the peritoneum transitions from the diaphragm onto the liver. Beneath the peritoneum lies a dense fibrous capsule (Glisson's capsule). Delicate Connective Tissue septa inside the liver divide its parenchyma into prismatic lobules, each approximately 1.5 mm in diameter. Within these septa between the lobules lie the interlobular Branches of the portal vein, hepatic artery, and bile ducts, which together form the portal triad (portal zone). Blood capillaries at the center of the lobule drain into the central vein. Central Veins converge and merge, progressively increasing in size to eventually form 2–3 hepatic veins that empty into the inferior vena cava.

Hepatocytes (liver Cells) within the lobules are arranged radially in hepatic cords (plates), interspersed with blood capillaries. Each hepatic cord is composed of two rows of liver cells, between which runs a bile canaliculus. Consequently, one side of each hepatocyte faces a blood capillary, while the opposite side borders a bile canaliculus. This structural arrangement enables metabolic products to pass directly from the cells into the blood capillaries (such as Proteins, glucose, Lipids, and Vitamins) and into the bile canaliculi (bile). The bile canaliculi originate blindly near the central vein and extend toward the periphery of the lobule, where they drain into the interlobular bile ducts. These interlobular ducts converge and enlarge, eventually forming the common hepatic duct at the porta hepatis through the junction of the right and left hepatic ducts, which drain bile from their respective lobes.