Enterohepatic circulation

Enterohepatic circulation refers to the circulation of biliary acids, bilirubin, drugs, or other substances from the liver to the bile, followed by entry into the small intestine, absorption by the enterocyte and transport back to the liver.

Overview

The liver plays a crucial role in the enterohepatic circulation. It produces bile, a fluid containing water, bile acids, and several waste products. Bile is stored in the gallbladder and released into the small intestine during digestion.

In the small intestine, bile acids aid in the digestion and absorption of dietary fats. After completing their role, they are reabsorbed into the bloodstream and returned to the liver, where they are reused. This process is known as the enterohepatic circulation.

Function

The primary function of the enterohepatic circulation is to conserve bile acids, which are synthesized from cholesterol in the liver, secreted into the bile, and passed into the small intestine.

In the intestine, bile acids emulsify dietary fats and facilitate their absorption. Approximately 95% of the bile acids are reabsorbed in the terminal ileum and transported back to the liver via the portal vein.

Clinical significance

Disruption of the enterohepatic circulation can lead to several health problems. For instance, if bile acids are not properly reabsorbed, they can cause diarrhea or malabsorption of dietary fats and fat-soluble vitamins.

Certain drugs can also affect the enterohepatic circulation. For example, cholestyramine, a bile acid sequestrant, binds to bile acids in the intestine and prevents their reabsorption. This drug is used to lower cholesterol levels in the body.

See also

• Bile acid
• Liver
• Small intestine
• Gallbladder
• Cholestyramine

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