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The muscle of the inner layer is arranged in circular rings around the tract, whereas the muscle of the outer layer is arranged longitudinally. The stomach has an extra layer, an inner oblique muscular layer. [1] Between the two muscle layers is the myenteric plexus (Auerbach's plexus). This controls peristalsis.
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 ]
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.
Measuring approximately 8 cm (3 inches) long in adults, [3] the portal vein is located in the right upper quadrant of the abdomen, originating behind the neck of the pancreas. [ 4 ] In most individuals, the portal vein is formed by the union of the superior mesenteric vein and the splenic vein . [ 5 ]
The gastroduodenal artery can be the source of a significant gastrointestinal bleed, which may arise as a complication of peptic ulcer disease.Because of its close relationship to the posteromedial wall of the second part of the duodenum, deeply penetrating ulcers or tumours of the duodenum may cause torrential bleeding from the gastroduodenal ‘artery of haemorrhage'. [1]
The tendency of the arteries and veins to stretch in response to pressure has a large effect on perfusion and blood pressure. This physically means that blood vessels with a higher compliance deform easier than lower compliance blood vessels under the same pressure and volume conditions. [1]
The right hepatic vein is the longest and largest of all the hepatic veins. It drains the liver segments VI and VII in their entirety, and variably participates in the drainage of segments V and VIII; the extent of drainage of the latter two segments by the right hepatic veins as opposed to the middle hepatic vein and possible variant accessory veins determines the calibre of the right hepatic ...
In the smallest vessels, the vessels' own circulation nourishes the walls directly and they have no vasa vasorum at all. Vasa vasorum are more frequent in veins than arteries. [ 2 ] Some authorities hypothesize that the vasa vasorum would be more abundant in large veins, as partial oxygen pressure and osmotic pressure is lower in veins.