Gall Blader and its functbbbbbbbions.pptx

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1. gallbladder

2. Introduction In vertebrates the gallbladder ( cholecyst Greek word, where " chole " means bile and "cyst" means bladder or sac, , gall bladder or biliary vesicle) is a small organ where bile is stored, before it is released into the small intestine. Humans can live without a gallbladder. The gallbladder is a hollow organ that sits just beneath the right lobe of the liver. 2 BRISSO ARACKAL

3. GALL BLADDER- definition Gall bladder is a pear shaped reservoir of bile situated in a fossa on the inferior surface of the right lobe of the liver. The fossa for the gall bladder extends from the right end of the porta hepatis to the inferior border of the liver

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5. DIMENSIONS AND CAPACITY The gall bladder is 7 to 10 cm long, 3 cm broad at its widest part, and about 30 to 50 ml in capacity. 5 BRISSO ARACKAL

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8. FUNCTIONS OF GALLBLADDER 1. Storage of Bile Bile is continuously secreted from liver. But it is released into intestine only intermittently and most of the bile is stored in gallbladder till it is required. 2. Concentration of Bile Bile is concentrated while it is stored in gallbladder. The mucosa of gallbladder rapidly reabsorbs water and electrolytes, except calcium and potassium. But the bile salts, bile pigments, cholesterol and lecithin are not reabsorbed. So, the concentration of these substances in bile increases 5 to 10 times.

9. 3. Alteration of pH of Bile The pH of bile decreases from 8 – 8.6 to 7 – 7.6 and it becomes less alkaline when it is stored in gallbladder. 4. Secretion of Mucin Gallbladder secretes mucin and adds it to bile. When bile is released into the intestine, mucin acts as a lubricant for movement of chyme in the intestine.

10. 5. Maintenance of Pressure in Biliary System Due to the concentrating capacity, gallbladder maintains a pressure of about 7 cm H2 O in biliary system. This pressure in the biliary system is essential for the release of bile into the intestine.

11. FUNCTIONS OF BILE 1. DIGESTIVE FUNCTION Emulsification is the process by which the fat globules are broken down into minute droplets and made in the form of a milky fluid called emulsion in small intestine, by the action of bile salts. Lipolytic enzymes of GI tract cannot digest the fats directly because the fats are insoluble in water due to the surface tension.

12. Bile salts emulsify the fats by reducing the surface tension due to their detergent action. Now the fats can be easily digested by lipolytic enzymes. Unemulsified fat usually passes through the intestine and then it is eliminated in feces. Emulsification of fats by bile salts needs the presence of lecithin from bile.

13. 2. ABSORPTIVE FUNCTIONS Bile salts help in the absorption of digested fats from intestine into blood. Bile salts combine with fats and make complexes of fats called micelles. The fats in the form of micelles can be absorbed easily.

14. 3. EXCRETORY FUNCTIONS Bile pigments are the major excretory products of the bile. Other substances excreted in bile are: Heavy metals like copper and iron Some bacteria like typhoid bacteria Some toxins Cholesterol Lecithin Alkaline phosphatase .

15. 4. LAXATIVE ACTION Laxative is an agent which induces defecation. Bile salts act as laxatives by stimulating peristaltic movements of the intestine.

16. 5. ANTISEPTIC ACTION Bile inhibits the growth of certain bacteria in the lumen of intestine by its natural detergent action

17. 6. CHOLERETIC ACTION Bile salts stimulate the secretion of bile from liver. This action is called choleretic action.

18. 7. MAINTENANCE OF pH IN GASTROINTESTINAL TRACT As bile is highly alkaline, it neutralizes the acid chyme which enters the intestine from stomach. Thus, an optimum pH is maintained for the action of digestive enzymes.

19. 8. PREVENTION OF GALLSTONE FORMATION Bile salts prevent the formation of gallstone by keeping the cholesterol and lecithin in solution. In the absence of bile salts, cholesterol precipitates along with lecithin and forms gallstone.

20. 9. LUBRICATION FUNCTION The mucin in bile acts as a lubricant for the chyme in intestine. „

21. 10. CHOLAGOGUE ACTION Cholagogue is an agent which causes contraction of gallbladder and release of bile into the intestine. Bile salts act as cholagogues indirectly by stimulating the secretion of hormone cholecystokinin. This hormone causes contraction of gallbladder, resulting in release of bile.