Question

What is enterohepatic circulation of bile salts? Mention its significance.

Answer 1

The liver is one of the most vital and exclusive organs that is found only in the vertebrates. It functions mainly to remove the toxins produced by the body through different metabolite actions and also aids in the process of digestion by production of certain biochemicals.

Complete answer:
The liver produces bile and bile acids. Bile is also known as gall and is produced which helps in the digestion of lipids in the small intestine. Bile acids are groups of steroid acids that conjugate with taurine or glycine to form anions called bile salts. The bile salts help in the digestion and metabolism of fat.

The circulation of the bile salts, bilirubin or other substances takes from the liver to the bile and then enters inside the small intestine which is further absorbed by the enterocyte and then transported back to the liver. This circulation or movement of the bile salts which involves the intestinal cells as well as the liver is known as the enterohepatic circulation of bile salts.

The bile acid is produced by the hepatocytes and it gets conjugated to glycine or taurine molecules. This gives rise to the formation of water soluble primary conjugated bile acids. These are called bile salts. It then travels to the gallbladder for further storage. It also moves towards the duodenum through the common bile duct during the process of digestion. The bile salts along with the digested food move to the ileum where they are reabsorbed actively in the hepatic-portal circulation. Some amount of the bile salts is also absorbed passively. Further, the venous blood from the ileum moves straight into the portal vein and then finally it moves to the liver sinusoids.

The major significance of the circulation is that it ensures the proper and efficient use of the bile secretion in the form of bile salts. The circulation allows the hepatocytes to extract the bile acids very efficiently which results in proper absorption of the bile salts and very less amount can escape into the systemic circulation. The process helps to reuse the bile salts around 20 times and sometimes multiple times during a single phase of digestion. This process also helps in the removal of several types of xenobiotics and toxins.

Hence, the correct answer is option (B).

Note: The liver is an organ that acts as the accessory organ for the process of digestion. It is made up of specialized cells which are known as the hepatocytes. The cells produce bile and bile salts which passes through a path of circulation from the liver to the small intestine where bile salts are absorbed by the enterocytes and further transported or absorbed back to the liver. This circulation known as the enterohepatic circulation of bile salts, maintains the efficiency and proper usage of bile salts.