Hepatic portal vein

The hepatic portal vein (often portal vein for short) is a portal vein in the human body that drains blood from the digestive system and its associated glands. It is one of the main components of the hepatic portal venous system.

Structure
It is formed by the union of the and divides into a right and a left branch before entering the liver.
 * splenic vein and
 * superior mesenteric vein

Note that the portal vein drains blood into the liver, not from the liver. The blood entering the liver from the portal vein, after being cleaned by the liver, flows into the inferior vena cava via the hepatic veins. The inferior mesenteric vein usually does not directly connect to the hepatic portal vein; it drains into the splenic vein.

Portal vein branches into many generation of vessels that open into hepatic sinusoids. Blood is recollected into the hepatic vein and enters the inferior vena cava.

Tributaries
The tributaries of the hepatic portal vein include:
 * Left gastric vein and right gastric vein
 * Superior mesenteric vein
 * Splenic vein

Physiology
Almost all of the blood coming from the digestive system drains into a special venous circulation called the portal circulation. This is because it contains all the nutrients and toxins that have been absorbed along the digestive tract from ingested food. Before these absorbed substances can go into the systemic circulation (the main blood circulation in the body), it must be filtered first to remove or "detoxify" toxic substances first. This filtering and detoxification is one of the functions of the liver.

Role in disease
Increased blood pressure in the portal vein, portal hypertension, occurs in liver disease (mainly cirrhosis), and may lead to various complications (ascites, esophageal varices, spontaneous bacterial peritonitis). A disruption of the hypothalamo-pituitary portal veins is referred to as Pickardt syndrome (suprasellar failure).

Portacaval anastomosis
The portal venous system has several anastomoses (portacaval anastomosis) with the systemic venous system. These are of consequence because in cases of portal hypertension these anastamoses may become engorged, dilated, or varicosed and subsequently rupture.

External link

 * - "Stomach, Spleen and Liver: The Visceral Surface of the Liver"

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