Portal venous system

Portal venous system

Portal venous system

The portal venous system is a major part of the circulatory system that carries blood from the gastrointestinal tract, gallbladder, pancreas, and spleen to the liver. This system is unique because it has two sets of capillaries, the first in the organs and the second in the liver.

Structure

The portal venous system begins in the capillaries of the organs it serves. These capillaries merge into larger veins, which eventually combine to form the portal vein. The portal vein then splits into smaller branches within the liver, leading to a second set of capillaries, the sinusoids. After passing through the sinusoids, the blood is collected into the hepatic veins, which drain into the inferior vena cava.

Function

The primary function of the portal venous system is to deliver nutrients and chemical signals from the gastrointestinal tract and other organs to the liver for processing. This allows the liver to regulate the levels of many substances in the body, including glucose, amino acids, and lipids. The portal venous system also carries toxins and other harmful substances to the liver, where they can be broken down and removed from the body.

Clinical significance

Disorders of the portal venous system can lead to serious health problems. For example, portal hypertension is a condition in which the blood pressure in the portal vein is too high, often due to cirrhosis of the liver. This can cause varices (enlarged veins) in the esophagus and stomach, which can rupture and cause life-threatening bleeding. Another condition, portal vein thrombosis, is a blood clot in the portal vein, which can block blood flow to the liver.

See also

• Hepatic portal vein
• Hepatic veins
• Cirrhosis
• Portal hypertension
• Portal vein thrombosis

External links

• Portal venous system at Medical Encyclopedia