The liver receives blood from two sources the hepatic artery delivers oxygenated blood, and the hepatic portal vein delivers deoxygenated blood containing newly absorbed nutrients, drugs, and microbes and toxins from the Gastrointestinal (GI) tract. Both end close to the porta hepatis when they divide into their right and left branches, which supply the left and right sides of the liver.
Branches of both the hepatic artery and the hepatic portal vein carry blood into the liver sinusoids, where oxygen, most of the nutrients, and certain toxic substances are taken up by the hepatocytes. Products manufactured by the hepatocytes and nutrients needed by other cells are secreted back into the blood, which then drains into the central vein and eventually passes, into a hepatic vein.
Branches of the hepatic portal vein, hepatic artery and bile duct accompany each other in there distribution through the liver. These 3 structures are called the portal triad. Portal triads are located at the corners of the liver lobules.
Hepatic Portal circulation
The hepatic portal circulation carries deoxygenated blood from the organs of the GI tract and the spleen to the liver.
The hepatic portal vein receives blood from capillaries of the GI organs and spleen and delivers it to the sinusoids of the liver. The hepatic portal blood is rich in nutrients absorbed from the GI tract. The liver stores some and modifies others before they pass into general circulation.
It also receives oxygenated blood via the hepatic artery, a branch of the celiac truck. The oxygenated blood mixes with the deoxygenated blood in the sinusoids.
Eventually the blood leaves the sinusoids of the liver through the central vein which drains into the hepatic veins and into the inferior vena cava. The attachment of these veins to the inferior vena cava helps keep the liver in place.
The hepatic portal vein is formed from the splenic and mesenteric veins. The superior mesenteric vein drains blood from the small intestine and portions of the large intestine, stomach and pancreas.
The splenic vein drains blood from the stomach, pancreas and portions of the large intestine.
The cystic vein opens into the splenic vein and drains the gallbladder
The lymphatic vessels of the liver occur as superficial vessels in the fibrous capsule which forms the outer surface of the liver and also as deep lymphatics in the connective tissue that accompanies the hepatic veins. Both types of lymphatic vessels converge at the porta hepatis and drain into the hepatic lymph nodes which are present along the hepatic vessels and ducts in the lesser omentum.
The nerves of the liver come from the hepatic nerve plexus, which is the largest branch of the celiac plexus. The hepatic plexus accompanies the branches of the hepatic artery and portal vein to the liver. It is formed from sympathetic fibres from the celiac plexus. The parasympathetic fibres come from the anterior and posterior vagal trunks. Nerve fibres accompany the vessels and bile ducts of the portal triad in the liver. They cause vasoconstriction of vessels, but other than this there function is unclear.