What is the Difference Between Hepatic Vein and Portal Vein?

The hepatic portal vein and hepatic vein are two distinct blood vessels involved in the liver's blood circulation. The main differences between them are:

1. Function: The hepatic portal vein carries nutrient-rich blood from the intestine, gallbladder, pancreas, and spleen to the liver for processing and filtering. On the other hand, the hepatic vein carries deoxygenated blood from the liver to the vena cava.
2. Blood Flow: The hepatic portal vein is responsible for transporting about 75% of the hepatic blood flow, making it a crucial part of the hepatic portal system. The hepatic vein, in contrast, carries blood out of the liver and back to the heart.
3. Anatomy: The hepatic portal vein is formed at the point where the superior mesenteric vein and splenic vein meet. It is the main vessel of the portal venous system and drains directly into the liver. The hepatic veins, on the other hand, are a set of three veins that drain blood from different parts of the liver.
4. Echogenicity: The portal vein wall typically appears hyperechoic over a wide range of beam-vessel angles, whereas the hepatic vein wall is hyperechoic only when the incident beam and the vessel are at a specific angle. This difference in echogenicity is attributed to marked discrepancies in mural thickness, collagen content, or perivascular fat between portal and hepatic veins.

Comparative Table: Hepatic Vein vs Portal Vein

Here is a table outlining the differences between the hepatic vein and the portal vein:

In summary, the hepatic vein transports blood from the liver to the inferior vena cava, which carries it to the right atrium of the heart. On the other hand, the portal vein receives blood from the stomach, intestines, pancreas, and spleen and carries it to the liver for processing. The portal vein contributes to approximately 75% of the liver's blood flow, while the hepatic vein does not have a specific percentage of contribution, as it transports blood from the liver to the heart.