Liver Essay Example | Topics and Well Written Essays - 2000 words

Liver - Essay Example These plates radiate from the central vein. Each of these plates is of thickness of two cells. Between the adjacent cells lie small bile canaliculi that empty into bile ducts in the fibrous septa separating the adjacent liver lobules. Blood from the venous outflow of the gastro intestinal tract reaches small portal venules in the septa by way of portal vein. Flat branching hepatic sinusoids, which lie between hepatic plates receive the blood from the portal venules. Afterwards the blood goes to central vein. Thus hepatic cells are continuously exposed to portal venous blood. In the interlobular septa, hepatic arterioles supply arterial blood to the septal tissues between the adjacent lobules. Many of these arterioles empty directly into the hepatic sinusoids in such a way that one third of the distance is away from the interlobular septa. The venous sinusoids are lined by two other types of cells namely, typical endothelial cells and larger Kupfer cells. The latter is also known as reticuloendothelial cells. The Kupfer cells are capable of phagocytosis, the process by which bacteria and other foreign matter in hepatic sinus blood are engulfed. The large pores in the lining of the endothelial cells facilitate free flow of the substances in plasma. Some pores are big enough to the tune of 1 micrometer in diameter. Millions of narrow tissue spaces called 'Spaces of Disse' lie between endothelial cells and hepatic cells. In the interlobular septa, these Spaces of Disse are connected with lymphatic vessels. Overflowing fluid in these spaces are thus removed by lymphatics. The large pores are helpful in diffusing even the large portions of plasma protein freely into this space. The functions of liver are versatile. Liver maintains filtration and storage of blood. Carbohydrates, protein, fats, hormones and foreign chemicals that are found in medications are metabolized at liver only. Liver stores vitamins and iron, which are necessary for the growth. The very important function of liver is formation of bile. It is through this bile secretion that many waste materials are excreted from liver. During medication, we consume many drugs such as sulfonamides, penicillin, ampicillin, and erythromycin. The active chemical medium present in liver detoxifies or excretes those drugs into bile. Accumulation of some steroid hormones like estrogen, coristol, aldosterone secreted by endocrine glands causes over activity of hormonal systems. Theses hormones are either chemically changed into other substances or excreted by the liver. Unwanted Calcium is excreted from the body only with help of the secretion from liver; from bile secretion the calcium reaches the gut and is lost finally in faeces. (Arthur C.Guyton and John E. Hall, 2000) One of the important excretory jobs carried out by the liver is removal of bilirubin. Bilirubin is formed continuously in the usual breakdown of the red blood cells. After circulating in the blood stream for about 120 days, in a normal healthy adult, the red blood cells wear out. These worn out red blood cells, haemoglobin, are converted into bilirubin, a yellow pigment. This bilirubin passes through the blood stream to liver, which is the only organ in our body capable of removing it. Metabolism of bilirubin takes places in three phases--- prehepatic, intrahepatic and post hepatic. In prehepatic phase about 80% of haemogulobin halves are metabolized to form bilirubin. Nearly 4mg/kg of bilirubin is produced in a