Bile is a bodily secretion produced in the liver that is released into the duodenum for digestive processes. Bile is stored in the gallbladder, which is connected to the liver and duodenum via bile ducts. Known disorders of bile include the formation of gallstones.
What is the gall bladder?
Schematic diagram showing the anatomy and structure of the gallbladder with gallstones. Click to enlarge. Properly referred to, bile is the digestive fluid produced in the liver that drains into the gallbladder where it is further thickened. The production of bile occurs outside of food intake. In common usage, bile is often referred to as the gallbladder itself. When the body ingests fatty food, bile is released and flows down a designated bile duct until it reaches the duodenum. Bile can have different colorations, depending on the amount of the red pigment bilirubin or the green pigment biliverdin. These dyes also color the feces that are later excreted differently. Fats are converted into digestible components by bile. In addition, bile transports other waste products from the liver out of the body.
Anatomy and structure
Bile is four-fifths water. In addition, there are bile salts, lecithin and the pigments. Other components are present in very small amounts, including the harmful substances secreted by the liver, which are transported further by the gallbladder. One of the main functions of bile is to bind cholesterol. This can only be achieved if a very sensitive ratio of lecithin, bile salts and cholesterol is maintained. A disturbance of this ratio leads to malfunctions and also, in the further course, to diseases. Bile is first collected in the gallbladder, which is located at the level of the liver on the right side of the body below the costal arches. It enters the sac-like structure of the gallbladder via the bile duct and the common bile duct. At this point, it is still thinner and only thickens into a much more viscous secretion in the gallbladder.
Functions and tasks
Bile performs an important function in the absorption of food. Bile divides fats into easily digested small droplets. This turns dietary fats into an emulsion that can be better metabolized by the secretions of the pancreas, which also enter the duodenum. Another function is related to the alkaline nature of bile. The food pulp pre-digested in the stomach is very aggressive due to gastric acid. It would be likely to attack the intestine without the neutralizing effect of bile. The release of bile into the digestive process is triggered by the absorption of fats. If this happens, the gallbladder contracts and the bile flows out through the main bile duct. If no fats enter the digestive process through food, the bile remains in the gallbladder. Since the liver produces about 700 ml of bile daily, thickening during this storage is a necessary process. The gallbladder would not be able to absorb such an amount in the first place. Moreover, the concentration further enhances the effect of bile.
Diseases
The gallbladder, filled with bile, is not necessary for a person’s survival. It can be removed if its function is impaired. A common disease of the gallbladder is the formation of gallstones. If the composition of the bile is not in balance, solids form from the excess components of the bile. These stone-like hardenings can be present in the gallbladder itself or become lodged in the bile duct. If they obstruct the outflow of bile there, colic-like pain results. Not all gallstones are noticed by those affected. Some leave the body naturally. Others cause irritation and inflammation. If gallstones cannot be removed or broken up by medical treatments, removal of the gallbladder follows. Less common is gallbladder inflammation without the presence of stones or a tumor of the gallbladder. Feeding problems after gallbladder removal are rare because bile is still produced in the liver in the less concentrated form.
Typical and common diseases
- Gallstones
- Gallbladder inflammation
- Gallbladder cancer and bile duct cancer
- Biliary colic
- Cholestasis
