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Encyclopedia > Portal vein

The portal vein is a major vein in the human body draining blood from the digestive system and its associated glands. It is formed by the union of the splenic and superior mesenteric veins. It divides into a right and left branches, before entering the liver. In biology, a vein is a blood vessel which returns blood from the microvasculature to the heart. ... For the Physics term GUT, please refer to Grand unification theory The gastrointestinal or digestive tract, also referred to as the GI tract or the alimentary canal or the gut, is the system of organs within multicellular animals which takes in food, digests it to extract energy and nutrients, and... A gland is an organ in an animals body that synthesizes a substance for release such as hormones, often into the bloodstream (endocrine gland) or into cavities inside the body or its outer surface (exocrine gland). ... The liver is an organ in vertebrates, including humans. ...


Note that the portal vein drains blood into the liver not from the liver. The blood entering the liver from the portal vein will then leave to the inferior vena cava through the hepatic veins. The liver is an organ in vertebrates, including humans. ... The liver is an organ in vertebrates, including humans. ... This article may be too technical for most readers to understand. ...


A second portal vein system connects hypothalamus and pituitary thus transferring releasing hormones with high concentration to the anterior pituitary lobe. In the anatomy of mammals, the hypothalamus is a region of the brain located below the thalamus, forming the major portion of the ventral region of the diencephalon and functioning to regulate certain metabolic processes and other autonomic activities. ... Located at the base of the skull, the pituitary gland is protected by a bony structure called the sella turcica. ... The main releasing hormones secreted by the hypothalamus are: Thyrotropin-releasing hormone (TRH), Corticotropin-releasing hormone (CRH), Gonadotropin-releasing hormone (GnRH), Growth hormone-releasing hormone (GHRH), Somatostatin, Dopamine. ...


Tributaries

The portal vein drains:

  • The posterior superior pancreaticoduodenal vein
  • The right gastric vein
  • The left gastric vein

Physiology

Almost all of the blood coming from the digestive system drains into a special venous circulation called the portal circulation. This is because it contains all the nutrients and toxins that have been absorbed along the digestive tract from ingested food. Before these absorbed substances can go into the systemic circulation (the main blood circulation in the body), it must be filtered first to remove or "detoxify" toxic substances first. This filtering and detoxification is one of the functions of the liver. For the Physics term GUT, please refer to Grand unification theory The gastrointestinal or digestive tract, also referred to as the GI tract or the alimentary canal or the gut, is the system of organs within multicellular animals which takes in food, digests it to extract energy and nutrients, and... Systemic circulation is a circuit of circulation in the cardiovascular system. ... Detox, short for detoxification, in general is the removal of toxic substances. ... For a list of biologically injurious substances, including toxins and other materials, as well as their effects, see poison. ...


Role in disease

Increased blood pressure in the portal vein, portal hypertension, occurs in liver disease (mainly cirrhosis), and may lead to various complications (ascites, esophageal varices, spontaneous bacterial peritonitis). A disruption of the hypothalamo-pituitary portal veins is referred to as Pickardt syndrome (suprasellar failure). Blood pressure is the pressure exerted by the blood on the walls of the blood vessels. ... In medicine, portal hypertension is hypertension (high blood pressure) in the portal vein and its branches. ... Cirrhosis is a chronic disease of the liver in which liver tissue is replaced by connective tissue, resulting in the loss of liver function. ... In medicine (gastroenterology), esophageal varices are extreme dilations of sub mucosal veins in the mucosa of the esophagus in diseases featuring portal hypertension, secondary to cirrhosis primarily. ... Spontaneous bacterial peritonitis is a form of peritonitis that occurs in patients with cirrhosis. ... ...


  Results from FactBites:
 
Encyclopedia of Surgery: A Guide for Patients and Caregivers - Pa-St (2741 words)
Portal vein bypass surgery diverts blood from the portal vein into another vein.
It is performed when pressure in the portal vein is so high that it causes internal bleeding from blood vessels in the esophagus.
The chemical causes the vein to become inflamed, which leads to the formation of fibrous tissue and closing of the lumen, or central channel of the vein.
Portal vein bypass (660 words)
The portal vein carries blood from the stomach and abdominal organs to the liver.
Portal vein bypass is usually performed as an emergency operation in a hospital under general anesthesia.
A catheter is threaded into the portal vein, and an expandable balloon or wire mesh is inserted to divert blood from the portal vein to the hepatic vein.
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