Physiology, Bile

Excerpt

Bile is a fundamental and unique secretion of the liver. It is a yellow-greenish fluid secreted from the hepatocytes and altered as it passes through the biliary tree by the epithelial cells lining the bile duct (cholangiocytes). After its secretion, bile is stored and concentrated in the gallbladder. Lipids in the duodenum stimulate the release of cholecystokinin, which stimulates gallbladder wall contraction, resulting in the release of bile into the cystic and common bile duct. The bile is composed mainly of water electrolytes and other substances, which include bile salts, cholesterol, bilirubin, lecithin, amino acids, drugs, toxins, heavy metals, and vitamins (see Image. Metabolic Pathway for Bilirubin in the Hepatocyte). Finding some hormones, proteins, and peptides in the bile secretions is also possible.