What is a Portal System?
A portal system is a system in which the veins start and end in capillaries. The venous blood collected from some part of the body is redistributed to some other organ instead of being directed to the heart.
Hepatic Portal System and Its Functions
The hepatic portal system is a system of veins. It comprises of the hepatic portal vein and its tributaries. It is also known as the portal venous system. The hepatic portal system is an important section of the circulatory system. However, there are other systems of veins in the body that are referred to as the portal venous system. The hepatic portal vein is the largest vein in the abdominal cavity. It drains blood from the spleen and the gastrointestinal tract to the liver. The hepatic veins begin at the junction of splenic veins and superior mesenteric. The blood from the cystic veins and the inferior mesenteric gastric veins is also drained by the hepatic vein. The ailments that affect the hepatic portal system should be identified and treated the earliest possible. If left untreated, might prove fatal. Medical conditions like portal hypertension caused by cirrhosis can affect the hepatic portal system. The blood that drains from the alimentary canal to the liver contains substances that are absorbed from the small intestine and pass through the liver before going back to the heart. It carries out the main function of further detoxifying deoxygenated blood before reaching the heart. This system is designed to eliminate toxic substances out of our body. This system is found in all the vertebrates. The entire gastrointestinal tract is not a part of this system. It extends from the lower portion of the oesophagus to the upper part of the anal canal.
Also read: Double Circulation
Veins that make up the Hepatic Portal System
The veins that make up the hepatic portal system are:
- Hepatic Portal Vein
- Splenic Vein
- Superior Mesenteric Vein
- Inferior Mesenteric Vein
Significance Of Hepatic Portal System
- The hepatic portal vein carries 75% of the hepatic blood flow and hence is crucial. It is not a true vein as it does not conduct blood directly to the heart.
- It supplies veins with metabolic substrates.
- It also ensures that food ingested is processed by the liver first before entering the systemic circulation. This way, ingested toxins are detoxified by hepatocytes.
- It also ensures that the liver is the first organ to absorb nutrients after intestines.
- The portal venous system captures substances from digestive organs and directs it for metabolism.
- It is important since it empties blood from the gastrointestinal tract into the liver. Before releasing into the bloodstream, the liver absorbs nutrients further for processing or storage for cellular use.
Also read: Blood Vessels
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