Final answer:
The middle hepatic vein is part of the liver's internal blood drainage system, which enters the inferior vena cava after the liver processes the blood. It is one vein in the dual blood supply of the liver, with the other being the hepatic portal vein carrying nutrient-rich blood from the intestines.
Step-by-step explanation:
The middle hepatic vein is part of the liver's blood drainage system and drains into the inferior vena cava (IVC). Within the hepatic portal system, the liver receives blood from both the hepatic portal vein and the hepatic artery.
The hepatic portal vein carries blood from the gastrointestinal tract and spleen, which is rich in nutrients and may contain toxins or drugs, to the liver for detoxification and metabolism. Once the liver processes this blood, it exits the liver through the right, left, and middle hepatic veins into the IVC. The largest vein entering the IVC, however, is the renal vein, which drains the kidneys.
Two separate blood supplies, systemic from the hepatic artery and nutrient-rich from the hepatic portal vein, allow the liver to effectively metabolize the absorbed digestive components, regulating the overall systemic blood composition.
After processing, the blood leaves the liver through the hepatic veins, with the middle hepatic vein being one of these, and then it combines with systemic blood in the IVC, returning to the heart.