FUNCTION OF LIVER, BILE & GALLBLADDER.pptx

FUNCTION OF LIVER, BILE & GALLBLADDER

1. LIVER, BILE & GALLBLADDER By Dr. Faraza Javaid

2. LIVER & GALLBLADDER The  liver  and  gallbladder  are the two accessory organs of the  gastrointestinal tract , which carry out a multifunctional role that aids digestion and homeostasis. The liver consists of several lobes and receives its blood supply mainly from the  hepatic portal vein .  The gallbladder is found inferiorly to the liver, being involved in the storage and release of bile into the  duodenum .

3. Location Liver:   Epigastric regions Gallbladder:  Right upper quadrant Parts Liver:   Diaphragmatic surface, visceral surface, right lobe, left lobe, caudate lobe, quadrate lobe, segments Gallbladder:  Fundus, body, beck, biliary tract Blood vessels Liver:   Hepatic artery, hepatic portal vein, hepatic veins Gallbladder:  Cystic artery, right hepatic artery, posterior superior pancreaticoduodenal artery, gastroduodenal arteries, cystic veins Innervation Sympathetic:   Celiac and superior mesenteric plexuses Parasympathetic:   Vagus nerve

4. LIVER Liver is made up of many lobes called hepatic lobes . Each lobe consists of many lobules called hepatic lobules . Hepatic lobule is the structural and functional unit of liver. There are about 50,000 to 100,000 lobules in the liver. The lobule is a honeycomb-like structure and it is made up of liver cells called hepatocytes Each lobule is surrounded by many portal triads. Each portal triad consists of three vessels: 1. A branch of hepatic artery 2. A branch of portal vein 3. A tributary of bile duct.

5. BILIARY SYSTEM Biliary system or extrahepatic biliary apparatus is formed by gallbladder and extrahepatic bile ducts (bile ducts outside the liver). Right and left hepatic bile ducts which come out of liver join to form common hepatic duct . It unites with the cystic duct from gallbladder to form common bile duct . All these ducts have similar structures.

6. Common bile duct unites with pancreatic duct to form the common hepatopancreatic duct or ampulla of Vater, which opens into the duodenum. There is a sphincter called sphincter of Oddi at the lower part of common bile duct, before it joins the pancreatic duct. It is normally kept closed; so the bile secreted from liver enters gallbladder where it is stored. Upon appropriate stimulation, the sphincter opens and allows flow of bile from gallbladder into the intestine.

7. PROPERTIES AND COMPOSITION OF BILE

8. Formation of Bile and Bile Salts

9. Bile acid synthesis occurs in  liver cells , which synthesize  primary bile acids  ( cholic acid  and  chenodeoxycholic acid  in humans) via  cytochrome P450 -mediated oxidation of  cholesterol  in a multi-step process. The  rate-limiting step  in synthesis is the addition of a hydroxyl group of the 7th position of the steroid nucleus by the enzyme  cholesterol 7 alpha-hydroxylase . This enzyme is  down-regulated  by cholic acid, up-regulated by cholesterol . In liver, bile acids are conjugated with glycine (amino acid) or taurin (derivative of an amino acid) and form conjugated bile acids . These bile acids combine with sodium or potassium ions to form the salts, sodium or potassium glycocholate and sodium or potassium taurocholate.

10. BILE PIGMENTS Bile pigments are the excretory products in bile. Bilirubin and biliverdin are the two bile pigments and bilirubin is the major bile pigment in human beings. Bile pigments are formed during the breakdown of hemoglobin, which is released from the destroyed RBCs in the reticuloendothelial system.

11. Formation of Bilirubin

12. FUNCTIONS OF BILE SALTS Emulsification of Fats (Fat breakdown) Absorption of Fats (Via Bile) Choleretic Action (Enhance bile secretion) Cholagogue Action (Gallb ladder contraction) Laxative Action (Stimulate peristalsis) Prevention of Gallstone Formation (Recycling of cholesterol)

13. FUNCTIONS OF GALLBLADDER Storage of Bile Concentration of Bile Maintenance of Pressure in Biliary System

14. FUNCTIONS OF LIVER METABOLIC FUNCTION STORAGE FUNCTION SECRETION OF BILE HEAT PRODUCTION HEMOPOIETIC FUNCTION INACTIVATION OF HORMONES AND DRUGS DEFENSIVE AND DETOXIFICATION FUNCTIONS

15. PATHOHYSIOLOGY OF LIVER & GALL BLADDER JAUNDICE OR ICTERUS HEPATITIS CIRRHOSIS OF LIVER GALLSTONES

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