Why does the liver have a hepatic portal vein and a hepatic vein?

The liver have a hepatic portal vein and a hepatic vein for blood flow and transport of nutrients.

Explanation:

Hepatic portal vein is also known as portal vein that carries blood from the organs (gastrointestinal tract, pancreas and gallbladder) to the liver. The nutrients are also transfer by the hepatic portal vein.

Hepatic vein: This vein carry deoxygenated blood into the inferior vena cava from the liver. Total three hepatic veins brings deoxygenated blood from right, left and middle part of liver.