Portal vein
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A portal vein is a vein that connects two systems of capillary beds. Regular veins arise in capillary beds and lead to the heart. In contrast to these, a portal vein does not take blood directly to the heart, but instead, takes blood to second capillary bed system.
In the human body, there are two main instances of portal systems:
- Hepatic portal vein - often referred to simply as the portal vein, this vein routes blood from the capillary beds of the gastrointestinal tract into the capillary beds of the liver. (See also portal venous system.)
- The portal venous system of the pituitary gland. (See also hypophyseal portal system.)