Physiology of the liver (original) (raw)

2017, International Journal of Research in Pharmacy and Biosciences

ABSTRACT In this paper the functions of the liver was summarized which includes firstly, Secretion of bile, the liver assists intestinal digestion by secreting 700 to 1200 ml of bile per day. Bile is an alkaline, bitter-tasting, yellowish green fluid that contains bile salts (conjugated bile acids), cholesterol, bilirubin (a pigment), electrolytes and water. It is formed by hepatocytes and secreted into the canaliculi. Bile salts, which are conjugated bile acids, are required for the intestinal emulsification and absorption of fats. Secondly, Metabolism of bilirubin which is a byproduct of destruction of aged red blood cells and gives bile a greenish black color and produces the yellow tinge of jaundice. Also Vascular and hematologic functions,because of its extensive vascular network, the liver can store a large volume of blood. The amount stored at anyone duration depends on pressure relationships in the arteries and veins. Moreover, the liver has hemostatic functions, It synthesizes prothrombin, fibrinogen, and clotting factors. Vitamin K, a fat-soluble vitamin, is essential for the synthesis of other clotting factors. Because bile salts are needed for reabsorption of fats, vitamin K absorption depends on adequate bile production in the liver. Furthermore Metabolism of nutrients, the liver plays essential roles in the metabolism of fat, protein and carbohydrates. Also, Metabolic detoxification, the liver alters exogenous and endogenous chemicals (e.g. drugs), foreign molecules, and hormones to make them less toxic or less biologically active. This process, called metabolic detoxification, diminishes intestinal or renal tubular reabsorption of potentially toxic substances and facilitates their intestinal and renal excretion. In this way alcohol, barbiturates, amphetamines, steroids and hormones (including estrogens, aldosterone, antidiuretic hormone, and testosterone) are metabolized or detoxified, preventing excessive accumulation and adverse effects. Also, Storage of minerals and vitamins, the liver stores certain vitamins and minerals, including iron and copper, in periods of excessive intake and releases them in periods of need. The liver can store vitamins B12 and D for several months and vitamin A for several years. The liver also stores vitamins E and K. Iron is stored in the liver as ferritin, an iron-protein complex and is released when needed for red blood cell production. Finally, the liver has immunologic functions as the liver contain cells involved in adaptive and innate immunity. Keywords: Liver, Physiology, Functions, Lobule, Hepatocytes.