Composition of Bile
Water - 97.5%
Solids - 2.5%
Solids contains
Organic substances - Bile salts
Bile pigments
Cholesteros
Fatty acids
Lecithin
Mucin
In organic substances Sodium
Potassium
Calcium
Chlorides
Bicarbonates
Formation of biles
Bile is produced continuously y by hepatocytes
Bile drains into the hepatic ducts and is stored in the gallbladder for subsequent release
Choleretic agents increase the formation of bile
Bile is formed by the following process
Primary acids
Ex – Cholic acid and chenodeoxycholic acid are synthesized from cholesterol by hepatocytes
Secondary bile acids
In the intestine , bacteria convert a portion of each of the primary bile acids to secondary bile acids (deoxycholic acid and lithocholic acid)
Synthesis of new bile acids occurs as needed , to replace bile acids that are excreted in the feces
The bile acids are conjugated with glycine or taurine to form their respective bile salts
Ex – Taurocholic acid is cholic acid conjugated with taurine
Electrolytes and H2O are added to the bile
During the interdigestive period m the gallbladder is relaxed the sphincter of Oddi is closed and the gallbladder fills with bile
The bile is concentrated in the gallbladder as a result of isosmotic absorption of solutes and H2O
Contraction of gallbladder
CCK
It is released in response to small peptides and fatty acids in the duodenum
It tells the gallbladder that bile is needed to emulsify and absorb lipids in the duodenum
It causes contraction of the gallbladder and relaxation of the sphincter of Oddi
Ach
It causes contraction of the gallbladder
Function of bile
1.Digestive function
2. Absorptive functions
3. Excretory function
Bile pigments are the major excretory products of the bile
The other substances excreted in bile are
Heavy metals like copper and iron
Some bacteria like typhoid
Some toxins
Cholesterol
Lecithin
4. Laxative action
5. Antiseptic action
Bile inhibits the growth of certain bacteria in the lumen of intestine by its natural
detergent action
6. Lubrication function
The mucin in bile acts as a lubricant for the chime in intestine
7.Maintenance of PH in GIT
It is highly alkaline, it neutralizes the acid chime which enters the intestine from stomach.
The optimum PH is maintained for the action of digestive enzymes
