Bile is the secret of hepatocyte liver cells. It accumulates in the small bile ducts, and then enters the common duct and through it into the gallbladder and duodenum. The functions of bile for the body are of great importance. One of its main functions is to participate in the digestive processes.
Where does bile accumulate?
The gall bladder is a storage reservoir for bile. During the period of the active phase of digestion, when partially digested food comes from the stomach to the duodenum, its maximum amount is allocated there. The main functions of human bile are participation in digestion and stimulation of secretory activity and motility of the small intestine, which also ensures the processing of the food lump.
Bile, which is secreted into the digestive tract from the gallbladder, is called mature, and secreted directly by the liver - young, or hepatic.
The process of bile formation and biliary excretion
The process of secretion of hepatocytes (choleresis) occurs continuously. They filter a number of substances from the blood into the bile capillaries. Further, due to the reabsorption of water and mineral salts, the final composition of this secretory liquid is formed. This process is carried out in the bile ducts and gall bladder. Part of the bile immediately enters the intestines, it is called hepatic, or young. But its main mass accumulates in the gallbladder, where it moves along the bile ducts. Bubble bile accumulates, becomes dense and concentrated. It is darker than hepatic.
For a day, liver cells in an adult produce about two liters of secretion. On an empty stomach, it practically does not enter the intestines. After eating, bile secretion (cholekinesis) in the duodenum 12 occurs. There, bile serves as a digestive, as well as bacteriostatic and regulatory. That is, it itself is a regulator of the process of bile formation and biliary excretion.
Thus, the more bile acids secreted into the portal bloodstream (portal vein), the higher their concentration in the bile composition and, accordingly, less synthesized by hepatocytes. The functions of bile and pancreatic juice are basic in digestion.
The composition of bile
The main component of bile are bile acids. Most (67%) are cholic acid and chenodeoxycholic. The remaining acids are secondary, i.e., derivatives of these two acids: deoxycholic, allocholic, lithocholic and ursodeoxycholic.
All bile acids are in this secret in the form of compounds with taurine and glycine. The content of a large number of sodium and potassium ions gives the bile an alkaline reaction.
In addition, the composition of bile includes some organic substances :
- Phospholipids.
- Protein compounds, namely immunoglobulins A and M.
- Bilirubin and biliverdin (bile pigments).
- Cholesterol.
- Mucin.
- Lecithin.
As well as ions of certain metals (zinc, copper, lead, magnesium, indium, mercury), vitamins A, B, C.
All of these components are part of both hepatic and cystic bile, but in the first their concentration is about 5 times lower than in the second.
Bile function
They are mainly associated with the work of the gastrointestinal tract. The functions of bile in digestion are associated with a number of enzymatic reactions.
- Under its influence, emulsification of fats occurs , thereby contributing to their absorption.
- It neutralizes the harmful effects of pepsin (the main component of gastric juice), which can destroy pancreatic enzymes.
- It activates the motility of the small intestine.
- Stimulates the production of mucus.
- It activates the production of gastrointestinal hormones: secretin and cholecystokinin, which are produced by the cells of the small intestine and help regulate the secretion of the pancreas.
- Prevents adhesion (adhesion) of bacteria and protein components.
- It has an antiseptic effect on the intestines and takes part in the formation of feces.
Thus, the functions of bile in the digestion cannot be overestimated. It is thanks to bile that the digestive process started in the stomach continues and ends safely in the intestine.
The value of bile for the human body
So, we found out that the main functions of bile are associated with the digestive process. What happens if, for some reason, the composition of bile changes or it does not enter the digestive tract? Lack or absence of it leads to serious pathologies:
- Gallstone disease.
- Steatorrhea.
- Gastroesophageal reflux disease (GERD) , etc.
Cholelithiasis
This pathology can occur due to an unbalanced composition of bile. This bile is called lithogenic. It can acquire such properties with regular errors in the diet, namely if animal fats predominate in food. The functions of liver bile may be impaired as a result of endocrine diseases. In addition, the hepatic secretion can acquire lithogenic properties as a result of lipid metabolism disturbance, which, as a rule, is accompanied by an increase in the patient’s body weight. Infectious and toxic liver lesions or an insufficiently active lifestyle (lack of exercise) can also cause changes in the composition of bile.
Steatorrhea
As mentioned above, the functions of bile are associated with the emulsification of fats. If for some reason bile ceases to enter the small intestine, absorption of fats does not occur, and they begin to be excreted in the feces. The same can happen when there is a lack of bile acids in this hepatic secretion (a change in its composition). In this case, the stool acquires a white or gray color and a greasy consistency. This pathology is called steatorrhea. With such a disease, the body lacks vital fats, fatty acids and some vitamins. Due to steatorrhea, the lower intestines suffer, because they are not adapted to such a chyme.
How is bile examined?
In order to investigate the composition and functions of bile, the method of fractional multi-moment duodenal sounding is used. This procedure consists of five steps:
- Basal secretion of bile - secretion of the common bile duct and 12 duodenal ulcer is released. It lasts about 15 minutes.
- Phase of secretory pause or closed sphincter of Oddi. The duration of this phase is 3 minutes.
- The phase of allocation of residual bile portion A. Lasts about 5 minutes.
- The phase of allocation of cystic bile portion B. This period lasts about 30 minutes.
- Isolation of hepatic bile - portion C. This phase lasts approximately 20 minutes.
Thus, 3 servings of bile are obtained. They all differ in composition. The most concentrated cystic bile is a portion of B. It contains the largest amount of fatty acids, bilirubin and other bile components.
This research method allows you to determine the physical properties of bile, its composition, volume of the gallbladder, the state of the biliary tract and to identify the localization of the pathological process.