*Portal vein – A vein that starts with capillaries and ends in capillaries is called portal vein.
What is Hepatic Portal System?
- Gastric vein from stomach, superior mesenteric vein from small intestine and inferior mesenteric vein from large intestine do not join the inferior vena cava directly instead they join together and form a single large vein called Hepatic Portal Vein which enters into the liver and breaks into capillaries. New capillaries are formed and they rejoin to form large hepatic vein. Hepatic vein now opens into the inferior vena cava that provides blood to the right auricle of the heart.
- All the portal veins that carry their contents into liver collectively constitute the Hepatic Portal System.
Utility / Significance of Hepatic Portal System
- It regulates the quantity of nutrients – The food absorbed by the stomach and intestine is first brought to the liver which acts like a store to regulate the quantity of nutrients flowing into general blood circulation. For e.g. , Excess glucose is converted into glycogen and required amount of glucose is released into the blood.
- Detoxification – Certain poisons, if absorbed through food , are toxified which means they are converted into harmless substances in the liver cells.