Hepatic portal system

(Redirected from Hepatic portal circuit)
Jump to navigation Jump to search

WikiDoc Resources for Hepatic portal system

Articles

Most recent articles on Hepatic portal system

Most cited articles on Hepatic portal system

Review articles on Hepatic portal system

Articles on Hepatic portal system in N Eng J Med, Lancet, BMJ

Media

Powerpoint slides on Hepatic portal system

Images of Hepatic portal system

Photos of Hepatic portal system

Podcasts & MP3s on Hepatic portal system

Videos on Hepatic portal system

Evidence Based Medicine

Cochrane Collaboration on Hepatic portal system

Bandolier on Hepatic portal system

TRIP on Hepatic portal system

Clinical Trials

Ongoing Trials on Hepatic portal system at Clinical Trials.gov

Trial results on Hepatic portal system

Clinical Trials on Hepatic portal system at Google

Guidelines / Policies / Govt

US National Guidelines Clearinghouse on Hepatic portal system

NICE Guidance on Hepatic portal system

NHS PRODIGY Guidance

FDA on Hepatic portal system

CDC on Hepatic portal system

Books

Books on Hepatic portal system

News

Hepatic portal system in the news

Be alerted to news on Hepatic portal system

News trends on Hepatic portal system

Commentary

Blogs on Hepatic portal system

Definitions

Definitions of Hepatic portal system

Patient Resources / Community

Patient resources on Hepatic portal system

Discussion groups on Hepatic portal system

Patient Handouts on Hepatic portal system

Directions to Hospitals Treating Hepatic portal system

Risk calculators and risk factors for Hepatic portal system

Healthcare Provider Resources

Symptoms of Hepatic portal system

Causes & Risk Factors for Hepatic portal system

Diagnostic studies for Hepatic portal system

Treatment of Hepatic portal system

Continuing Medical Education (CME)

CME Programs on Hepatic portal system

International

Hepatic portal system en Espanol

Hepatic portal system en Francais

Business

Hepatic portal system in the Marketplace

Patents on Hepatic portal system

Experimental / Informatics

List of terms related to Hepatic portal system


Overview

In human anatomy, the hepatic portal system is the system of veins that comprises the hepatic portal vein and its tributaries. It is also called the portal venous system, although it is not the only example of a portal venous system.

Function

The portal venous system is responsible for directing blood from parts of the gastrointestinal tract to the liver. Things absorbed in the small intestine, for example, would be taken to the liver for processing before being sent to the heart. Many drugs that are absorbed through the GI tract are substantially metabolized by the liver before reaching general circulation. This is known as the first pass effect.

Not all of the gastrointestinal tract is part of this system. The system extends from about the lower portion of the esophagus to the upper part of the anal canal. It also includes venous drainage from the spleen and pancreas. This explains why certain drugs can only be taken via certain routes. For example, nitro-glycerin cannot be swallowed, but it can be taken under the tongue. The detoxification powers of the liver are strong enough to inactivate the medication before it reaches the heart. Therefore, nitroglycerin is given in a way that bypasses the portal venous system.

Blood flow to the liver is unique in that it receives both oxygenated and deoxygenated blood. As a result, portal blood has lower pO2 and perfusion pressure than the other organs of the body. Blood passes from branches of the portal vein through cavities between "plates" of hepatocytes called sinusoids. Blood also flows from branches of the hepatic artery and mixes into the sinusoids to supply the hepatocytes with oxygen. This mixture percolates through the sinusoids and collects in a central vein which drains into the hepatic vein. The hepatic vein subsequently drains into the inferior vena cava.

Large veins that are considered part of the portal venous system are the:

Roughly, the portal venous system corresponds to areas supplied by the celiac trunk, the superior mesenteric artery, and the inferior mesenteric artery.

Pathology

Portal hypertension is a condition in which the blood pressure of the portal venous system is too high. It is often the result of cirrhosis of the liver.

See also

References

Template:Veins of the torso

Template:WH Template:WikiDoc Sources