The Anatomy of the Biliary System and Bile Formation

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@elity-sitio is here again, welcome to my blog, and today I will be discussing the Anatomy of the Biliary system. Without any delay, let's get started. The Biliary system is the combination of organs and ducts that produces, store, and transports bile, which is produced by the liver.

The liver is a large reddish-brown meaty organ situated on the right abdominal quadrant of the abdomen, we could say that it is specifically at the right hypochondria abdominal region, although its left lobe can touch the epigastric region. It is divided into two lobes, the right lobe, and the left lobe. The right lobe is the larger part of the liver while the left side is the smaller part of the liver. The lobes are divided by a ligament known as the Falciform ligament which connects the liver to the diaphragm and the anterior abdominal wall. The right lobe can be divided into two other sub-lobes which are the caudate lobe and the quadrate lobe, as they belong morphologically to the right lobe but structurally speaking, they can be said to be part of the left lobe. The liver possesses three borders which are the upper lower and right border, the liver also has five surfaces which are the anterior surface, the inferior surface, the posterior surface, the anterior surface, and the right lateral surface or the quadrilateral surface.


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Bile is made up of certain components which include bile acid which is derived from cholesterol (Cholic acid, and Chino Deoxycholic acid), phospholipid (phosphatidylcholine, phosphatidyl serine), conjugated bilirubin, electrolytes, amino acid, glutathione, and water. For bile creation, different molecules and substances need to be available. to do this, the Na+-taurocholate cotransporting polypeptide (NTCP transporter) takes up bile acid and sodium in the biliary cell. Organic anions transporter proteins also bring in anions such as drugs and they can also bring in bile acids, also another transporter known as organic cations also brings in organic cations such as drugs. Bilirubin is brought up into the cell through the bilirubin transporter from the liver. Bilirubin is the breakdown product of heme from hemoglobin in the blood, which is done in regions where there are sinusoidal capillaries such as the bone marrow, the liver, and the spleen (majorly). The Hemoglobin when broken down is divided into two products which are heme and globin. Globin is broken down into amino acids which can be sent to different locations such as the bone marrow to produce hemoglobin again, and the liver for protein. heme is then broken down to biliverdin via heme oxygenase, bilirubin via biliverdin reductase, and iron. When bilirubin is made, it is sent into circulation where albumin produced by the liver binds with it making it unconjugated bilirubin. The iron goes back into circulation bonded with transferrin to prevent free radicals in the blood, or it is bound with apoferritin to become ferritin, which then becomes hemosiderin. The unconjugated bilirubin is taken in by the liver where the albumin dissociates from the bilirubin. The bilirubin is sent to the smooth endoplasmic reticulum, and it interacts with UDP-glucuronosyltransferase (UGT) making the bilirubin more polar/conjugated. The liver excretes the conjugated bilirubin into the biliary system through the Multidrug Resistance Associated Protein 2 (MRP-2) transporter.

Bile produced in the liver helps to emulsify fat in the duodenum. The liver has a gallbladder which is a pear-shaped structure located in the upper right quadrant of the abdomen, just below the liver and its function is to store and concentrate bile. Bile is produced in the hepatocyte of the liver cells and they are transported through the bile canaliculi, then it gets to the bile duct. The bile duct which exists as the left hepatic duct and the right hepatic duct merges together to become the common hepatic duct. In the gallbladder, there is a cystic duct that stores the bile. if the bile leaves the gallbladder, it can combine with the common hepatic duct to become the common bile duct that is outside the liver. In the pancreas, there is a duct known as the pancreatic duct which merges with the common bile duct at the hepatopancreatic ampulla which is also known as the sphincter of Oddi which goes into the duodenum where fat is emulsified by bile.

Conclusion

The aim of discussing the anatomy of the biliary system is to be able to explain the process of bile production, and bile transportation to the duodenum from the liver for fat emulsification. In other to absorb fat, the liver, and the biliary system are important, the small intestine needs to be in good condition, and the pancreas.

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