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The human hepatic portal system delivers about three-fourths of the blood going to the liver.The final common pathway for transport of venous blood from spleen, pancreas, gallbladder and the abdominal portion of the gastrointestinal tract [2] (with the exception of the inferior part of the anal canal and sigmoid colon) is through the hepatic portal vein.
Portal hypertension is a condition in which the blood pressure of the portal venous system is too high. It is often the result of cirrhosis of the liver. Liver cirrhosis can lead to increased intrahepatic vascular resistance and vasodilation of portal system arteries, both of which increase pressure in the portal vein. [4]
It is a major component of the hepatic portal system, one of three portal venous systems in the human body; the others being the hypophyseal and renal portal systems. The portal vein is usually formed by the confluence of the superior mesenteric , splenic veins , inferior mesenteric , left , right gastric veins and the pancreatic vein .
A portacaval anastomosis or portocaval anastomosis is a specific type of circulatory anastomosis that occurs between the veins of the portal circulation and the vena cava, thus forming one of the principal types of portasystemic anastomosis or portosystemic anastomosis, as it connects the portal circulation to the systemic circulation, providing an alternative pathway for the blood.
Portal venous systems. A portal venous system is a series of veins or venules that directly connect two capillary beds. The two systems in verebrates are the hepatic portal system, and the hypophyseal portal system. Anastomoses. An anastomosis is a joining of two structures such as blood vessels.
In histology (microscopic anatomy), the lobules of liver, or hepatic lobules, are small divisions of the liver defined at the microscopic scale. The hepatic lobule is a building block of the liver tissue, consisting of a portal triad, hepatocytes arranged in linear cords between a capillary network, and a central vein.
Portal hypertension, an important consequence of liver disease, results in the development of significant collateral circulation between the portal system and systemic venous drainage (porto-caval circulation). Portal venous congestion causes venous blood leaving the stomach and intestines to be diverted along auxiliary routes of lesser ...
A dilated portal vein (diameter of greater than 13 or 15 mm) is a sign of portal hypertension, with a sensitivity estimated at 12.5% or 40%. [18] On Doppler ultrasonography, a slow velocity of <16 cm/s in addition to dilatation in the main portal vein are diagnostic of portal hypertension. [19]