Question

The Hepatic Portal Vein is one of the most unusual blood vessels in the body. It carries blood from the capillaries of almost the whole digestive system to the liver where it goes through another set of capillaries before returning to the heart. In addition, it is the only vein that does not have valves. Given these characteristics describe and explain the structure of the vessel as it pertains to vascular resistance.

Answer 1

Hepatic portal vein system is used to collect blood from the different parts of digestion so as to supply to the liver. The hepatic portal veins have a unique structure. The resistance to flow blood through the hepatic portal vein is very low. Even though they have no valves this is done by their special arrangement. The conducting blood vessel that comes out of the acinus flows through 20 hepatocyte and then terminate to the venules. So the blood can pass through it so easy. Thus a continuous flow is maintained inside the system. As the blood vessel connects to the cappilary beds like this and then the blood is taken from there by the hepatic vein the supply of the blood to heart is made simple like other vein system. Blood from the intestinal regions are detoxified here by this method. As they can flow directly to liver and their division into microvasculature makes the blood flow easily through it creating less vascular resistance. From the capillary bed the blood flow start like other vein systems. Hepatic portal veins are not true veins as the open to artery cappilary bed.