The role of bile

"肝胆相照" is an idiom, which shows that the relationship between the liver and gallbladder is very close, and the liver and gallbladder in the human body cannot be seen. The pig's liver and gallbladder can often be seen. The gallbladder is like a small soft bottle filled with a dark green liquid. People are accustomed to calling bile bitter gall because bile is a very bitter substance. There is a bile duct on the gallbladder that connects to the intestines. The bile in the gallbladder is secreted by liver cells.

The liver secretes bile every moment, storing the bile in the gallbladder when you are not eating, and then releasing the bile into the duodenum to aid digestion when you eat. The main function of bile is to digest lipids, and it also helps digest some proteins, sugars, etc.

Bile is an essential substance for the digestion of lipid foods and is the final product of cholesterol metabolism in the body. Primary bile acids flow into the intestine with bile. While promoting lipid digestion and absorption, they are transformed into secondary bile acids by the action of bacteria in the intestine (the lower end of the small intestine and the large intestine). About 95% of the bile acids in the intestine are reabsorbed by the intestinal wall (including active reabsorption and passive reabsorption). The reabsorbed bile acids return to the liver through the portal vein, are processed by hepatocytes, and are discharged into the intestine through the bile duct together with newly synthesized conjugated bile acids. This process is called the enterohepatic circulation of bile acids. The content of bile acid in the body is about 3 to 5 grams. Even if all of it is dumped into the small intestine after a meal, it is difficult to reach the critical concentration required for digesting lipids. However, since 2 to 4 enterohepatic circulations can be performed after each meal, the limited bile can play its role to the maximum extent, thereby maintaining the normal digestion and absorption of lipid foods.

The insoluble bilirubin in the blood is directly absorbed into the liver cells and released into the bile ducts, where it forms bile with bile salts, cholesterol, etc. and is discharged into the duodenum. The bile salts help the digestion and absorption of fat.

If the gallbladder has gallstones, cholecystitis or other gallbladder diseases, the first symptom is that the patient cannot eat oily food. The symptoms of gallstones and cholecystitis are pain in the right upper abdomen, and in some patients the pain may radiate to the right shoulder. Bile is a digestive fluid that digests fats, but it does not contain digestive enzymes. Bile plays an important role in the digestion and absorption of fat.