Biliary System Dr Mahvash Khan Biliary System Includes
Biliary System Dr. Mahvash Khan
Biliary System Includes n Liver n Gallbladder n Ducts
Liver is the largest organ in the body p Liver Has Very High Lymph Flow (half of the lymph formed in the body under resting conditions) p Liver Has High Blood Flow and Low Vascular Resistance (1350 ml/min) (27% of the cardiac output) p The basic functional unit of liver is the “liver lobule”(50, 000 -1000, 000) p
Blood Supply of Liver p Sources (Two) n n n Hepatic Artery Hepatic Portal Vein Blood is drained into Hepatic Vein which joins inferior venacava
Physiologic Anatomy of Liver p Functional Units (Lobules) n n Hexagonal Arrangement of Tissues around central Vein Branch of Hepatic Artery, Hepatic portal vein and a bile duct at the outer edge of Lobule
Functions of liver Metabolic Functions p Synthetic Functions p Storage Functions p Blood reservoir p Hemopoietic Function p Blood Cleansing Function p Activation of Vitamin-D p Excretory Functions p Digestive Function p
Functions of liver- Metabolic Functions p Carbohydrate Metabolism n n n p Blood Glucose Buffer system Storage of Glycogen Conversion of Galactose & Fructose to Glucose Gluconeogenesis Formation of Many chemical compounds from intermediate products of Carbohydrate metabolism Protein Metabolism n n n Deamination of Aminoacids Formation of Urea Synthesis of Plasma Proteins Synthesis of Clotting Factors Interconversion of Various Amino acids
Functions of liver- Metabolic Functions (Con’d) p Fat Metabolism n n n Oxidation of Fatty acids to supply energy Synthesis of cholesterol, phospholipids & lipoproteins Synthesis of fat from proteins & carbohydrates
Functions of liver- Synthetic Functions Synthesis of plasma proteins p Synthesis of clotting factors (factor VII, IX, X, prothrombin, fibrinogen) p Synthesis of various proteins required for the transport of Steroid & Thyroid Hormones p
Functions of liver- Storage Functions p Storage of: n n Iron Copper Glycogen Vitamins (A, D, B 12)
Functions of liver- Blood reservoir & Hemopoietic Function p Blood Reservoir (Blood sinusoids-dilated capillaries) p Hemopoietic Function n In fetal life
Functions of liver- Blood Cleansing Function Removal of bacteria (by Kupfer cells) p Detoxification of drugs & chemicals (like penicillin, sulfonamides) p Removal of old red blood cells p
Functions of liver- Activation p of Vitamin-D Formation of 25 hydroxycholecalciferol
Functions of liver- Excretory Excretion p of of Functions calcium through gut bilirubin cholesterol hormones
Functions of liver- Digestive Functions p Role of Bile salts in digestion & Absorption of fats
Bile Secretion by Liver Bile is secreted by Liver p Normally between 600 and 1000 ml/day p Bile is secreted in two stages p
Bile plays an important role in fat digestion and absorption q Bile serves as a means for excretion of several waste products from the blood such as bilirubin, (end product of hemoglobin destruction), excess cholesterol, certain hormones etc p
Composition of Bile Water Bile salts Bilirubin Liver Bile 97. 5 g/dl 1. 1 g/dl 0. 04 g/dl Gallbladder Bile 92 g/dl 6 g/dl 0. 3 g/dl Cholesterol 0. 1 0. 3 -0. 9 g/dl Fatty Acids Lecithin Na+ K+ Ca++ Cl. HCO 3 - 0. 12 g/dl 0. 04 g/dl 145 m. Eq/l 100 m. Eq/l 28 m. Eq/l g/dl 0. 3 -1. 2 g/dl 0. 3 g/dl 130 m. Eq/l 12 m. Eq/l 23 m. Eq/l 25 m. Eq/l 10 m. Eq/l
Secretion of Bile by liver p p 250 ml to 1 liter per day Continuous secretion by hepatocytes Aqueous alkaline fluid Important organic constituent n n p p Bilirubin Cholesterol Lecithin Bile salts Taken by common bile duct to the duodenum Enterohepatic circulation
Bile Salts p Derivatives of Cholesterol n n n Cholic acid & Chenodeoxycholic acid Conjugation with glycine & taurine Sodium salts of conjugated acids Average amount 3 to 4 gms in the body p Only 5% excreted in faeces p Powerful choleretics p
Stimulus for Bile secretion p Chemical Mechanism n p Hormonal Mechanism n p Bile Salts Secretin Neural Mechanism n Vagalstimulation
Gallbladder p Site n n p Sac like structure Located beneath the liver Functions n n Storage of bile Concentration of bile
Gallbladder Functions: Storage of bile Can store 450 ml of bile (12 hr of secretion) p Transported to the Gallbladder between the meals p
Gallbladder Functions: Concentration of bile Active transport of salts p Water following osmotically p Concentration of bile 5 to 10 times p
Gallbladder : Emptying of Gallbladder Relaxation of sphincter of ODDI p Contraction of gallbladder p Role of cholecystokinin p Stimulation by fatty foods in duodenum p
Gallbladder : Formation of Gall stones Common site of formation of stones p 75% of stones made of cholesterol p 25% made of bilirubin p In case of Gallbladder removal bile is stored in common bile duct which becomes dilated p
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