Library · Anatomy
Portal circulation
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Blood leaving the digestive tract does not go straight to the heart. The veins that drain the stomach, the small and large intestine, the pancreas, the spleen and the gallbladder all come together into a single vein, the portal vein, and that is the venous entrance to the liver. Everything that was absorbed passes first through a single doorway.
When the portal vein reaches the hilum, the point where the liver's vessels enter and leave, it divides into a right branch and a left branch, and from there it empties into the hepatic sinusoids, wide channels that run between the liver cells.
The liver receives blood by two routes at once. About 75% arrives through the portal vein and the rest through the hepatic artery, and the two mix right there, inside the sinusoid.
The way out has its own order too. From the sinusoids the blood moves to the central veins, from there to the hepatic vein, and from there to the inferior vena cava, which returns it to the heart.
In brief
The veins of the digestive tract merge into the portal vein, the liver's only venous inlet.
Everything absorbed in the intestine passes first through a single doorway before it reaches the rest of the body.
At the hilum it divides into right and left branches and empties into the hepatic sinusoids.
It supplies about 75% of the liver's blood and the hepatic artery the rest; the two mix there.
From there blood moves to the central veins, the hepatic vein and the inferior vena cava.
Sources (1)
- National Center for Biotechnology Information, StatPearls PublishingAnatomy, Abdomen and Pelvis, Portal Venous System (Hepatic Portal System), StatPearlsPublished
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