A portal venous system is defined as one beginning and ending in capillaries. The name "portal vein" derives from the notion that it is the gate through which the blood from the splanchnic circulation system (composed of gastric, small intestinal, colonic, pancreatic, hepatic, and splenic circulations) is connected to the liver. The name portal vein is applied to the venous system that originates in the capillaries of the intestines and terminates in the hepatic cells called sinusoids. 3
Portal vein is a short, thick trunk formed by the union of several veins through which oxygen-depleted blood from the stomach, the intestines, the spleen, the gallbladder, and the pancreas flows to the liver. In the liver the blood from the portal vein flows through a network of microscopic vessels called sinusoids in which the blood is cleared from dead cells, bacteria, and other waste products. 1
Portal hypertension is the obstruction of portal venous blood through external pressure on the portal vein. It results from the relationship between blood flow volume entering the portal system and resistance to portal blood. 2 It may be caused by abscesses, tumors, or by hepatic fibrosis constriction, and liver cirrhosis. It causes gastrointestinal bleeding, ascites, portal-systemic encephalopathy, hepato-renal syndrome, hepato-pulmonary syndrome, and spontaneous bacterial peritonitis.
- Encyclopædia Britannica Online, s. v. "liver sinusoid"
- Plinio Rossi, Paolo Ricci, Laura Broglia. Portal Hypertension: Diagnostic Imaging and Imaging-Guided Therapy
- Arun J. Sanyal, Vijay H. Shah. Portal Hypertension: Pathobiology, Evaluation, And Treatment