enterohepatik

Enterohepatic circulation refers to the process by which certain substances, primarily bile acids, are reabsorbed in the intestine and transported back to the liver via the bloodstream. This cycle plays a crucial role in maintaining bile acid homeostasis, which is essential for digestion and absorption of dietary fats and fat-soluble vitamins. The term "enterohepatic" combines "enteron," meaning intestine, and "hepatic," referring to the liver.

During enterohepatic circulation, bile acids secreted by the liver into the duodenum aid in emulsifying dietary fats. After facilitating digestion, most bile acids are reabsorbed in the terminal ileum through active and passive transport mechanisms. From there, they enter the portal circulation and are carried back to the liver, where they are either reused for bile production or metabolized. This continuous loop ensures efficient recycling of bile acids, conserving bile salts and minimizing waste.

The process is regulated by hormonal and physiological feedback mechanisms. For instance, bile acids stimulate the release of cholecystokinin (CCK) from the duodenum, which promotes gallbladder contraction and bile release. Additionally, the liver modulates bile acid synthesis in response to circulating levels, preventing excessive accumulation.

Disruptions in enterohepatic circulation can lead to clinical consequences, such as diarrhea in cases of bile acid malabsorption or altered drug metabolism due to impaired recycling. Conditions affecting bile acid synthesis, absorption, or transport—such as certain liver diseases, ileal resection, or genetic disorders—may disrupt this cycle, necessitating medical evaluation and management. Understanding enterohepatic circulation is vital for diagnosing and treating gastrointestinal and metabolic disorders.