Hepatic Portal System


A portal system in the human body refers to the circulation of draining blood composed of one set of vessels that delivers the blood to the capillaries and then are picked up by the systemic veins and taken to the vena cava. The hepatic portal system refers to the veins responsible for the drainage of blood from the capillaries in the spleen, stomach, intestines, pancreas, and gallbladder.


These capillaries are initially drained into the capillary sinusoid of the liver. This blood is then picked up by the hepatic veins that also drain the blood from the liver. From there it is taken to the inferior vena cava.

The hepatic portal system is designed to require the digested elements to pass through the liver before entering the general circulation. The digestive organs are then drained by the hepatic portal vein. This vein is created by the conjuncture of the superior mesenteric vein and the splenic vein.


Hepatic Portal System
Image: Hepatic Portal System

The splenic vein is responsible for blood flow from the spleen while the superior mesenteric vein is responsible for the blood flow coming from the small intestine and is remarkably high in nutrients. Three tributaries which meet with the splenic vein, the inferior mesenteric vein, the pancreatic vein, and the gastroepiploic vein, engorges the splenic vein to several times the original necessary size. The stomach drains into the left gastroepiploic vein.

The pancreas drains into the pancreatic vein. Finally, the inferior mesenteric vein is responsible for the blood flow out of the large intestine. The superior mesenteric vein receives the blood flow from the right gastroepiploic vein which is responsible for providing additional drainage to the stomach.

The hepatic vein receives three additional veins. Included would be the left and right gastric veins and the veins from the gallbladder. The gastric veins provide drainage for the lesser curvature of the stomach and the gallbladder is drained by the cystic vein.
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