Wednesday, March 4, 2009

The Hepatic Portal System of Circulation


Circulation: "The Hepatic Portal System of Circulation.
This system serves the intestines, spleen, pancreas and gall bladder. The liver receives it blood from two main sources. The main sources are the hepatic artery, which as a branch of the aorta, supplies oxygenated blood to the liver and the hepatic portal vein, which is formed by the union of veins from the spleen, the stomach, pancreas, duodenum and the colon. The hepatic portal vein transports, inter alia, the following blood to the liver:
absorbed nutrients from the duodenum;
white blood cells (added to the circulation) from the spleen;
poisomous substances, such as alcohol which are absorbed in the intestines, and
waste products, such as carbon dioxide from the spleen, pancreas, stomach and duodenum.
The hepatic artery and hepatic portal vein open into the liver sinuses where the blood is in direct contact with the liver cells. The deoxygenated blood, which still retains some dissolved nutrients, eventually flows into the inferior vena cava via the hepatic veins.Coronary Circulation.
This circulation supplies the heart muscle itself with oxygen and nutrients and conveys carbon dioxide and other waste products away from the heart. Two coronary arteries lead from the aorta to the heart wall, where they branch off and enter the heart muscle. The blood is returned from the heart muscle to the right atrium through the coronary vein, which enters the right atrium through the coronary sinus"

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