Liver is like government: when it functions well, no one pays attention to it.

What is Liver ?
The largest solid organ in the body, situated on the right side below the diaphragm. The liver occupies the right hypochondrium (the epigastrium) and part of the left hypochondrium, and is level with the bottom of the sternum. Its undersurface is concave and covers the stomach, duodenum, hepatic flexure of colon, right kidney, and adrenal capsule. The liver secretes bile and is the site of numerous metabolic functions.

Anatomy of Liver
The liver consists of four lobes, five ligaments, and five fissures, and is covered by a tough fibrous membrane called Glisson's capsule, which is thickest at the transverse fissure. At this point the capsule carries the blood vessels and hepatic duct, which enter the organ at the hilus. Strands of connective tissue originating from the capsule enter the liver parenchyma and form the supporting network of the organ and separate the functional units of the liver, the hepatic lobules.
The many intrahepatic bile ducts converge and anastomose, finally forming the secretory duct of the liver, the hepatic duct, which joins the cystic duct from the gallbladder to form the common bile duct or the ductus choledochus, which enters the duodenum at the papilla of Vater. A ring of smooth muscle at the terminal portion of the choledochus, the sphincter of Oddi, permits the passage of bile into the duodenum by relaxing. The bile leaving the liver enters the gallbladder, where it undergoes concentration principally through loss of water absorbed by the gallbladder mucosa. When bile is needed in the small intestine for digestive purposes, the gallbladder contracts and the sphincter relaxes, thus permitting escape of the viscid gallbladder bile. Ordinarily, the sphincter of Oddi is contracted, shutting off the duodenal entrance and forcing the bile to enter the gallbladder after leaving the liver.
The functional units of the liver are the liver lobules, six-sided aggregations of hepatocytes permeated by capillaries called sinusoids. Lining these sinusoids are Kupffer cells, the macrophages of the liver.

Blood circulation in Liver
The liver is supplied with oxygenated blood from the hepatic artery, a branch of the celiac artery, and blood from all the digestive organs and spleen by way of the portal vein. The end products of digestion and other materials thus pass through the liver before entering general circulation.

Innervation to Liver
The nerve supply consists of parasympathetic fibers from the vagi and sympathetic fibers from the celiac plexus via the hepatic nerve.

The function of Liver
The liver is the most metabolically active organ of the body.