How does the hepatic portal vein differ from other veins?
A vein arises from venules of capillary bed and drains in a larger vein or in the heart. The hepatic portal vein arises from capillary bed of one organ and ends in capillary bed of another organ.
Hepatic portal vein arises from mainly from the gastrointestinal tract and a tributary that comes from the spleen. The vessel, only three inches in length in an adult, thus receives deoxygenated blood and drains into the nearby liver.
Thus it could be safely said that the Hepatic Portal Vein is not able to supply necessary oxygen to liver tissue . (For that purpose, hepatic artery brings oxygenated blood.)
The significance of the portal vein lies in the fact that it
1. receives absorbed nutrients from intestine, and
2. delivers most of those to the metabolic hub of the body, i.e. to the liver
before returning the blood to systemic circulation.