In the human body, some organs are represented in pairs: lungs, kidneys, limbs. Others - these are mainly organs of the abdominal cavity - are unpaired: spleen, intestines, stomach. This explains the features of blood supply to the abdominal cavity, especially the formation of the venous system. The portal vein is a vessel through which blood flows from the internal organs to the liver.
Why does a person need a portal vein
It should be noted that this blood vessel is a unique anatomical formation of the human body.
First, the portal vein is the shortest blood vessel of this caliber. Its length is only 5-7 cm (from the moment of merging of the mesenteric veins and spleen veins to the place of entry of this blood vessel into the liver), while the diameter of this vein can even be up to 1.5-2 centimeters in the absence of pathology.
Secondly, along this venous trunk, all the blood coming from the digestive tract is collected and delivered to the liver cells, where it is disinfected.
However, the portal vein system is not limited to this vessel. It includes veins that connect in it, and those hepatic veins into which this trunk breaks up after getting into the liver. Directly at the gate of the liver, the vein is divided into the right and left branches, which, in turn, branch further and further until they reach the liver lobules.
Accordingly, all blood passes through this blood vessel, which is collected from the organs of the abdominal cavity (primarily from the digestive tract). In the liver cells, metabolic processes of decomposition and transformation of most harmful substances into useful or indifferent to the body occur.
The portal vein has collateral (bypass) connections with the veins of the stomach. Therefore, when an obstacle arises in it, untreated blood enters the other organs of the human body, very quickly causing characteristic symptoms of intoxication, while changes in the venous system of the stomach resemble those that occur when hemorrhoids develop in the veins of the rectal plexus.
Diseases of the portal vein - how they manifest
At present, portal vein thrombosis is the most common disease of this blood vessel. The occurrence of it in the vast majority of cases signals the presence in the human body of problems requiring the initiation of immediate and effective treatment. Most often, this disease develops in patients who suffer from malignant neoplasms of the liver, cirrhosis, severe bleeding disorders, sepsis.
In this case, qualified medical care should be provided in full. If untreated, this condition leads to the rapid development of liver abscesses, acute liver failure, and patient death. At the same time, an examination should be conducted, the purpose of which should be to identify the cause of the violation of the blood flow in the portal vein system.
Why not all medicines can be taken orally
It should be noted that most of the medications prescribed to humans are absorbed in the intestines and necessarily enter the portal vein.
In some cases, the ingestion of a drug substance into the liver is necessary. There, it turns from an inactive form into an active one and begins its therapeutic effect.
In other cases, medication entering the liver is undesirable. The only way to prevent this is by the resorption of the drug in the oral cavity (some heart drugs - nitroglycerin and its derivatives, cardiac glycosides), rectal administration or injection. In this case, the portal vein will not participate in the transport of the drug.