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The inferior mesenteric vein connects in the majority of people on the splenic vein, but in some people, it is known to connect on the portal vein or the superior mesenteric vein. Roughly, the portal venous system corresponds to areas supplied by the celiac trunk, the superior mesenteric artery, and the inferior mesenteric artery.
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 .
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.
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 is defined as increased portal venous pressure, with a hepatic venous pressure gradient greater than 5 mmHg. [3] [4] Normal portal pressure is 1–4 mmHg; clinically insignificant portal hypertension is present at portal pressures 5–9 mmHg; clinically significant portal hypertension is present at portal pressures greater than 10 mmHg. [5]
hepatic portal vein (entering) The hepatic duct lies in front and to the right, the hepatic artery to the left, and the portal vein behind and between the duct and artery. It also transmits nerves and lymphatics. Sympathetic nerves - these provide afferent pain impulses from the liver and gall bladder to the brain.
However, significant hepatic extraction still occurs because of second pass metabolism, whereby a fraction of venous blood travels through the hepatic portal vein and hepatocytes. The four primary systems that affect the first pass effect of a drug are the enzymes of the gastrointestinal lumen , gut wall enzymes, bacterial enzymes, and hepatic ...
Blood flow through the left coronary artery is at a maximum during diastole (in contrast to the rest of systemic circulation, which has a maximum blood flow during systole.) splanchnic circulation: 15%: low: Flow increases during digestion. hepatic circulation: 15%: Part of portal venous system, so oncotic pressure is very low renal circulation ...