What is a portal vein? Give an example.

1.	What is a portal vein? Give an example.
Answer» The\xa0portal venous system\xa0refers to the vessels involved in the drainage of the capillary beds of the GI tract and spleen into the capillary bed of the liver.\xa0Blood\xa0flow to the liver is unique in that it receives both oxygenated and deoxygenated\xa0blood.\xa0In carrying venous blood from the gastrointestinal tract to the\xa0liver, the portal vein accomplishes two tasks: it supplies the\xa0liver\xa0with metabolic substrates and it ensures that substances ingested are first processed by the\xa0liver\xa0before reaching the systemic circulation.

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