The Portal Vein
Portal venous system : a venous capillary bed draining into another venous capillary bed instead of into the heart.
Commonly it refers to the hepatic portal sytem
Another portal venous system is hypophyseal portal system
Formation of the portal vein
Tributaries of the hepatic portal system :
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A system wherein the venous blood
starts from the capillary bed
and conveys the blood
to another capillary system
instead of to the heart
Venous blood from abdominal digestive organs, the spleen and pancreas are drained into the liver.
Passing through another capillary bed (hepatic sinusoids) blood enters the inferior vena cava through the hepatic veins and go to the heart
Thus blood with high concentraion of nutrient materials absorbed from the stomach and intestines goes to the liver first for metabolism.
Formed by the union of the following veins:-
Inferior mesenteric vein
Superior mesenteric vein
The splenic vein drains - blood from the spleen, the pancreas and part of the stomach.
The inferior mesenteric vein - blood from rectum, pelvic and descending colon. It joins the splenic vein
The superior mesenteric vein - blood from small intestine and the proximal colon - caecum, ascending and transverse colon. It unites with the the splenic vein and forms the portal vein
The gastric veins - glood from the stomach and the distal end of the oesophagus, then joins the portal vein.
The cystic vein - from gall bladder - joins the portal vein directly
very short veins - blood from liver into the IVC
The portal vein is found in the free edge of lesser omentum along with the hepatic artery
In Cirrhosis of the liver the portal venous system is constricted and obstructed
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