Hepatic portal system
The liver is the largest and heaviest gland in the human body, which is responsible for protein production, excretion of toxins and storage of sugar, fat, etc. But the liver has a different function from other organs in the body, and that is that all the blood that leaves our digestive system enters the liver through a vein called the portal vein and It divides into branches in the liver, and after reconnecting its branches, it forms a large vein that enters the right atrium of the heart. The portal vein set and its branches inside the liver are called the "hepatic portal system".
The liver portal system is very important. Port system diseases and increased portal vein blood pressure can seriously endanger our health. In this article, we will talk more about the liver port system.
What is the function of the liver port system?
The hepatic port system is made up of the portal vein and its branches. The portal vein brings blood out of the spleen, pancreas, stomach, esophagus and intestines into the liver to be refined and prepared before entering the heart. The portal vein provides the liver with the carbohydrates absorbed from the intestines, which are the fuel for the liver.
It is better to get a little familiar with the anatomy of the liver to understand the liver port system better.
Liver anatomy:
The liver has four lobes (parts). The thin tissue (connective tissue) that divides the liver into four lobes creates smaller divisions inside each lobe, called the lobes of the liver (lobules). The area of the liver that is located in the lower part and where arteries and nerves enter the liver is called the liver umbilicus.
The liver lobules under the microscope are polygonal, that are arranged side by side. In the figure below, you can see a number of polygonal lobules of the liver together. The liver lobule is made up of cell plates called hepatocytes and in the center of each hepatic lobule is the central or central vein. At each apex of this irregular polygon (the liver lobule); There is a triple set called the port triad.
In fact, the liver cells or hepatocytes that are in the lobule are located next to very, very thin branches of the arteries, and their job is to filter the blood inside these narrow arteries. These very delicate vascular bifurcations of hepatocytes are called sinusoids.
The umbilicus of the liver:
Two blood vessels enter the umbilicus of the liver:
One is the portal vein, which we say carries blood that collects from the gastrointestinal tract (from the end of the esophagus to the anus) and enters the liver for purification and preparation, and the second is the hepatic artery, which contains oxygenated blood to keep the liver alive.
Both of these vessels begin to divide inside the liver and eventually attach to sinusoids and hepatocytes. Hepatocytes consume the oxygenated blood in the sinusoids and process and purify the blood from the gastrointestinal tract.
The blood that comes out of the hepatocytes enters the thin vessels that connect and form a single vein called the hepatic vein. This vein eventually flows into the great inferior vena cava and travels to the heart.
What is meant by triad port?
A set of three numbers is located at the apex of the lobules of the liver and is called the triad port, which includes the following:
- A small branch of the port vein
- A small branch of the hepatic artery
- A small branch of the bile duct
What is a Portal hypertension?
Hypertension of the hepatic portal vein is called hypertension portal, which is accompanied by the following symptoms:
- Gastrointestinal bleeding (black stools and foul-smelling bloody vomit)
- Abdominal ascites (accumulation of fluid in the abdominal space)
- Decreased level of consciousness due to liver dysfunction (Hepatic Encephalopathy)
- Decreased platelet count and white blood cells
Causes of Portal hypertension:
Causes of port hypertension are divided into the following types:
- Disorders that originate outside the liver, such as :
Clot formation in the portal vein
- Disorders that originate in the liver, such as:
Congenital liver fibrosis
Sarcaidosis (a disease associated with the growth of inflammatory cells)
Lymphomas
Leishmaniasis parasite
Cirrhosis of the liver (the most common cause of portal hypertension)
- Budd–Chiari syndrome (obstruction of the outflow veins of the liver)
- Right heart failure
- And fistulas and other vascular disorders (Arterio portal fistula or malformation)