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The liver is the largest gland in the body (approximately 1500 grams) and is located in the right upper quadrant of the abdomen. It is glossy in appearance and dark red in color from the rich supply of blood flowing through it. Approximately 25% of the cardiac output flows to the liver. It performs many important functions: 　　(1).the uptake, storage, and disposal of nutrients (protein, carbohydrates and fat), drugs, toxins .      (2).the production of synthetic proteins (critical for blood clotting) and metabolism of substances produced by the body. Anatomy of the Liver He anterior surface of the liver is triangular in shape, made of two lobes. The right lobe is the larger of the two, measuring 6 to 7 inches in length. The left lobe is 3 inches in length. Ligaments connect the upper surface of the liver to the diaphragm and the abdominal wall and the under surface to the stomach and duodenum. The gall bladder is located on the under surface of the right lobe of the liver. Neighboring organs include the colon, the intestines, and the right kidney. The Liver Up Close When viewed under a microscope, the liver is seen as large network of units called hepatic lobules. The hepatic lobule is very small and looks like a six-sided cylinder. The lobule itself is surrounded by connective tissue and has 5 to 7 clusters of vessels around its edges. These vessels include a branch of the portal vein, a branch of the hepatic artery, and a bile duct. A central vein runs through the middle of the lobe and is surrounded by cords of liver cells that radiate out in all directions. Between these cords are wide thinwalled blood vessels called sinusoids. All of the blood drains into a hepatic vein which then circulates throughout the body. Digestive Function of the Liver Sometimes referred to as the great chemical factory of the body, the liver creates, regulates, and stores a variety of substances used by the gastrointestinal system, and it serves a number of important digestive functions.
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The main digestive chemical synthesized by the liver is bile. During a meal, bile is secreted by liver cells and travels through the hepatic duct system into the small intestine where it is used to break down fat molecules.
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Between meals, bile is stored in the gall bladder. Bile further serves as a waste disposal system for toxins removed from the blood by the liver. The liver also plays a major role in the regulation of blood glucose (blood sugar). The liver synthesizes, dissolves, and stores amino acids, protein, and fat.It stores several important vitamins like B12 and Vitamin A. The liver also disposes of cellular waste and breaks down harmful substances, like alcohol. Circulatory Function of the Liver While the liver is technically part of the gastrointestinal system, it also plays an important role in blood circulation. The liver has been called the antechamber of the heart because it collects and processes all of the gastrointestinal blood through the portal vein and delivers it to the right side of the heart. The liver receives blood through two vascular systems, the portal vein and hepatic artery. Liver Cancer There is no consensus regarding the optimal treatment of patients with liver tumors. This contributes to the pessimistic attitude that many have regarding the treatment of liver cancer. Aggressive treatment strategies can cure or significantly prolong the life of many patients with liver cancer. The liver is a common site of metastases from a variety of organs such as lung, breast, colon and rectum. When liver metastases occur at the time of initial diagnosis of the primary tumor, they are described as synchronous. If detected after the initial diagnosis, they are described as metachronous. The liver is frequently involved since it receives blood from the abdominal organs via the portal vein. Malignant cells detach from the primary cancer, enter the bloodstream or lymphatic channels, travel to the liver, and grow independently. We do not understand the mechanism of how a tumor cell can leave the primary site and grow in specific organs. Potentially, the environment of the liver is suitable to the growth of certain tumor cells. Once a tumor begins to grow in the liver, it receives its blood supply from the hepatic artery.                                                                                                                                                                     2010-07-29
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