The portal vein and its tributaries. It is formed by the superior mesenteric vein and splenic vein. Leinal vein is an old term for splenic vein.
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|Latin
|colspan="2"|vena portæ
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|colspan="2"|[subject #174 ]
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|Drains from
|colspan="2"|splenic vein, superior mesenteric vein
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|Drains to
|colspan="2"|liver
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|Artery
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|MeSH
|colspan="2"|[A07.231.908.670.567]
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|Dorlands/Elsevier
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The portal vein is a vein in the human body that drains blood from the digestive system and its associated glands. It is formed by the union of the
and divides into a right and a left branch, before entering the liver.
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 does not directly connect to the portal vein; it drains into the splenic vein.
A second portal vein system connects hypothalamus and pituitary, thus transferring releasing hormones with high concentration to the anterior pituitary lobe.
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.
