Answer
The main function of the hepatic portal circulation is to take the blood from the digestive organs, spleen and pancreas and deliver this it to the liver via hepatic portal vein. When we eat food this blood contains large amount of nutrients received from digestion of food, this system takes this blood to liver for processing these substances. It is unique because generally arteries feed capillary beds, which in turn drain into veins, however in the hepatic portal circulation, veins feed the liver circulation.
Work Step by Step
Same as above.