zsírsavelállítás

Zsírsavelállítás refers to the process of bile acid synthesis in the liver. Bile acids are crucial for the digestion and absorption of fats and fat-soluble vitamins in the small intestine. The primary site of bile acid synthesis is the liver, where cholesterol is converted into bile acids through a series of enzymatic reactions.

This process begins with the rate-limiting enzyme cholesterol 7α-hydroxylase (CYP7A1). This enzyme catalyzes the first and most crucial step in the classic pathway of bile acid synthesis. Following this initial hydroxylation, further modifications occur, including reduction, epimerization, and de novo synthesis of a side chain. The main primary bile acids produced are cholic acid and chenodeoxycholic acid.

Once synthesized, these primary bile acids are conjugated with either glycine or taurine, forming bile salts. These bile salts are then secreted into the bile and stored in the gallbladder. Upon consumption of a fatty meal, the gallbladder contracts, releasing bile into the duodenum. In the small intestine, bile salts emulsify fats, increasing their surface area for digestion by lipases.

The majority of bile acids are reabsorbed in the ileum through active transport and returned to the liver via the portal vein, a process known as enterohepatic circulation. A small percentage is lost in the feces and is replenished by de novo synthesis in the liver. This enterohepatic circulation is highly efficient, with over 95% of bile acids being recycled. Bile acids also play signaling roles in the body, affecting glucose and lipid metabolism through their interaction with specific nuclear receptors.