Composition of Bile Secretion, The Secretion of Liver

Bile is a golden or brownish yellow fluid that is secreted by the parenchymal cells of the liver. It is collected in small ductules that join together to form right and left hepatic bile ducts. The right and left hepatic ducts combine together to form a common hepatic duct. Common hepatic duct joins with the cystic duct to form common bile duct and common bile duct empties into the second part of the duodenum, after joining the pancreatic duct at Ampula of Vater. Cystic duct transport the bile secretion between the gallbladder and the common bile duct. The gallbladder stores the bile. Cholelithiasis and Choledocholithiasis mean the presence of stones in the gallbladder and common bile duct respectively, may occur due to a disturbance in the composition of bile.

Composition of Bile

Bile is composed of following ingredients.

1. It is composed mainly of water, inorganic and organic matter
2. Inorganic constitutes: These include sodium, chloride, bicarbonate and potassium. Bicarbonate helps to neutralize the acidic food that is received by the proximal portion of small intestine. It also makes the pH of intestine basic that is necessary for proper functioning of intestinal digestive enzymes.
3. Organic constitutes: Theses include;
1. Bile salts: (Cholic acid and Chenodeoxycholic acid). bile salts help in digestion and absorption of fats, fat-soluble vitamins and carotenes.
2. Bile pigments: (bilirubin & biliverdin). These give golden or brownish yellow colour to bile. These are the breakdown products of haemoglobin. If haemoglobin breakdown increases as in the case of hemolytic anaemia it. It concentration in blood increases that gives a generalized yellowish look to the patient. This condition is called jaundice.
3. Mucin: It helps to lubricate the food particles.
4. Fatty acids
5. Phospholipids
6. Cholesterol: it is an excretory product of bile. Increases cholesterol excretion may help in the formation of gallstone formation.
4. pH of bile ranges between 7.8 to 8.6. It has basic pH because of the presence of high concentration of HCO3 (bicarbonate).