Bile is the secret of liver cells of hepatocytes. It accumulates in the small bile ducts, and then enters the common duct and through it into the gallbladder and duodenum 12. The functions of bile for the body are of great importance. One of its main functions is participation in the processes of digestion.
Where does bile accumulate?
The gallbladder is a storage reservoir for bile. During the active phase of digestion, when partially digested food enters the duodenum from the stomach, the maximum amount of it is released 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 bolus.
The bile that is secreted into the digestive tract from the gallbladder is called mature, and the bile secreted directly by the liver is called young, or hepatic.
The process of bile formation and bile secretion
The process of producing hepatocyte secretion (choleresis) is continuous. They filter a number of substances from the blood into the bilecapillaries. Further, due to the reabsorption of water and mineral s alts, the final formation of the composition of this secretory fluid occurs. This process takes place in the bile ducts and gallbladder. Part of the bile immediately enters the intestines, it is called hepatic, or young. But its bulk accumulates in the gallbladder, where it moves through the bile ducts. Cystic bile accumulates, becomes thick and concentrated. It is darker than liver.
During the day, the 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) occurs in the duodenum. There, bile performs a digestive function, as well as a bacteriostatic and regulatory one. That is, it is itself a regulator of the process of bile formation and bile secretion.
Thus, the more bile acids are released into the portal circulation (portal vein), the higher their concentration in the bile composition and, accordingly, the less is synthesized by hepatocytes. The functions of bile and pancreatic juice are essential in digestion.
Composition of bile
Bile acids are the main component of bile. Most (67%) are cholic acid and chenodeoxycholic acid. 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. High content of sodium and potassium ionsmakes bile alkaline.
In addition, bile contains some organic substances:
- Phospholipids.
- Protein compounds, namely immunoglobulins A and M.
- Bilirubin and biliverdin (bile pigments).
- Cholesterol.
- Mucin.
- Lecithin.
And also some metal ions (zinc, copper, lead, magnesium, indium, mercury), vitamins A, B, C.
All of the listed components are present in both hepatic and gallbladder bile, but in the former their concentration is about 5 times lower than in the latter.
Functions of bile
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, fats are emulsified, thereby facilitating their absorption.
- It neutralizes the harmful effects of pepsin (the main component of gastric juice), which can destroy pancreatic enzymes.
- Activates small intestine motility.
- Stimulates mucus production.
- Activates the production of gastrointestinal hormones: secretin and cholecystokinin, which are produced by the cells of the small intestine and contribute to the regulation of the secretory work of the pancreas.
- Prevents adhesion (adhesion) of bacteria and protein components.
- Has an antiseptic effect on the intestines and takes part in the formation of feces.
Thus, the function of bile in digestion is overestimatedimpossible. It is thanks to bile that the digestive process, started in the stomach, continues and ends safely in the intestines.
The value of bile for the human body
So, we found out that the main functions of bile are related to 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:
- Cholelithiasis.
- Steatorrhea.
- Gastroesophageal reflux disease (GERD) and others
Cholelithiasis
This pathology may occur due to an unbalanced composition of bile. Such 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 the bile of the liver can be impaired as a result of endocrine diseases. In addition, this hepatic secret can acquire lithogenic properties as a result of lipid metabolism disorders, which, as a rule, is accompanied by an increase in the patient's body weight. The reason for the change in the composition of bile can also be infectious and toxic liver damage or an insufficiently active lifestyle (physical inactivity).
Steatorrhea
As mentioned above, the functions of bile are related to the emulsification of fats. If, for some reason, bile stops flowing into the small intestine, fats are not absorbed, and they begin tobe excreted in feces. The same can happen with a lack of bile acids in this hepatic secretion (change in its composition). In this case, the feces acquire a white or gray color and a greasy texture. This pathology is called steatorrhea. With such a disease, the body lacks vital fats, fatty acids and some vitamins. As a result of steatorrhea, the lower intestines suffer, because they are not adapted to such chyme.
How is bile examined?
In order to investigate the composition and functions of bile, the method of fractional multi-stage duodenal sounding is used. This procedure consists of five steps:
- Basal secretion of bile - secretion of the common bile duct and duodenum occurs. Lasts about 15 minutes.
- Phase of secretory pause or closed sphincter of Oddi. The duration of this phase is 3 minutes.
- Residual bile release phase of portion A. Lasts about 5 minutes.
- Cyccile bile release phase of portion B. This period lasts about 30 minutes.
- Excretion of hepatic bile - portion C. This phase lasts approximately 20 minutes.
Thus, get 3 servings of bile. All of them differ in composition. The most concentrated gallbladder bile is portion B. It contains the highest amount of fatty acids, bilirubin and other bile components.
This research method allows you to determine the physical properties of bile, its composition, the volume of the gallbladder, the state of the biliary tract and identify localizationpathological process.
