The human liver is an organ located within the abdomen, with its larger lobe on the right side of the body. The liver is the largest gland in the body and possesses remarkable regeneration capabilities. The gland secretes bile, a green-colored digestive enzyme stored in the gall bladder during fasting. Bile acids aid in digestion, among other functions.
The sympathetic nervous system stimulates bile production. Its production is continuous although lowest during fasting, as it is needed most during digestion and comes at a high metabolic cost. Production slows to conserve energy for immediately needed metabolic processes.
The human liver produces approximately 400ml to 800ml of bile each day. Hepatocytes of the liver secrete bile, which is then released into the canaliculi before entering the bile ducts. The bile ducts add to this secretion a liquid rich with bicarbonates. Next, a hormone called cholecystokinin (CCK), causes gall bladder contraction, which discharges bile into the duodenum. The duodenum is the first section of the small intestine. Here the fluid mixes with pancreatic enzymes to further digest the food. The fluid is alkaline and neutralizes stomach acids in the small intestine.
What Bile Does
Bile contains bilirubin, bile acids, cholesterol and phospholipids. Together, these components aid in digestion by acting as a detergent, emulsifying fats. Bile also aids in waste elimination by the liver.
The breakdown of hemoglobin produces bilirubin. Bilirubin is generally considered waste, but it's also a powerful antioxidant that reduces peroxyl oxidants. An abnormal accumulation of bilirubin within the body results in jaundice, which is noted as a yellowish skin discoloration.
Bile acids are cholesterol derivatives with amphipathic faces. This means their faces have both hydrophobic and hydrophilic properties. These properties are what allow the acids to effectively emulsify lipids and transport them through aqueous environments.
Bile Secretion Antagonists
Gall stones are the most common antagonists of bile secretion. The stones form from hardened bile and block gall ducts. The most common solution is to remove the gall bladder, as it is not a vital organ.
Cirrhosis is a disease of the liver. Diseases including chronic hepatitis, chronic alcoholism, bile duct disorders and hereditary disorders cause cirrhosis. Cirrhosis scars the liver and prevents the flow of bile in and out of the organ.
Tumors within the bile ducts may also impair bile secretion. The two most common types are Klatskin's and distal bile duct tumors. The most effective treatment for distal duct tumors is to completely remove the tumor, along with a Whipple operation (see Resources). The most common treatment for Klatskin's tumors is to remove the tumor completely, along with removing one lobe of the liver.