Biliary System
Dr. Mahvash Khan
Biliary SystemIncludes
Liver Gallbladder Ducts
Liver is the largest organ in the body Liver Has Very High Lymph Flow (half of the
lymph formed in the body under resting conditions)
Liver Has High Blood Flow and Low Vascular Resistance (1350 ml/min) (27% of the cardiac output)
The basic functional unit of liver is the “liver lobule”(50,000-1000,000)
Blood Supply of Liver Sources (Two)
Hepatic Artery Hepatic Portal Vein Blood is drained into
Hepatic Vein which joins inferior venacava
Physiologic Anatomy of Liver
Functional Units (Lobules) 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 Synthetic Functions Storage Functions Blood reservoir Hemopoietic Function Blood Cleansing Function Activation of Vitamin-D Excretory Functions Digestive Function
Functions of liver- Metabolic Functions Carbohydrate Metabolism
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
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) Fat Metabolism
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 Synthesis of clotting factors (factor VII, IX,
X, prothrombin, fibrinogen) Synthesis of various proteins required for
the transport of Steroid & Thyroid Hormones
Functions of liver- Storage Functions Storage of:
Iron Copper Glycogen Vitamins (A,D,B12)
Functions of liver- Blood reservoir & Hemopoietic Function Blood Reservoir (Blood sinusoids-dilated
capillaries)
Hemopoietic Function In fetal life
Functions of liver- Blood Cleansing Function Removal of bacteria (by Kupfer cells) Detoxification of drugs & chemicals (like
penicillin, sulfonamides) Removal of old red blood cells
Functions of liver- Activation of Vitamin-D Formation of 25 hydroxycholecalciferol
Functions of liver- Excretory Functions
Excretion of calcium through gut Excretion of bilirubin Excretion of cholesterol Excretion of hormones
Functions of liver- Digestive Functions
Role of Bile salts in digestion & Absorption of fats
Bile Secretion by Liver Bile is secreted by Liver Normally between 600 and 1000 ml/day Bile is secreted in two stages
Bile plays an important role in fat digestion and absorption 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
Composition of BileLiver Bile Gallbladder Bile
Water 97.5 g/dl 92 g/dl Bile salts 1.1 g/dl 6 g/dlBilirubin 0.04 g/dl 0.3 g/dlCholesterol 0.1 g/dl 0.3-0.9 g/dlFatty Acids 0.12 g/dl 0.3-1.2 g/dlLecithin 0.04 g/dl 0.3 g/dlNa+ 145 mEq/l 130 mEq/lK+ 5 mEq/l 12 mEq/lCa++ 5 mEq/l 23 mEq/lCl- 100 mEq/l 25 mEq/lHCO3- 28 mEq/l 10 mEq/l
Secretion of Bile by liver 250 ml to 1 liter per day Continuous secretion by hepatocytes Aqueous alkaline fluid Important organic constituent
Bilirubin Cholesterol Lecithin Bile salts
Taken by common bile duct to the duodenum Enterohepatic circulation
Bile Salts Derivatives of Cholesterol
Cholic acid & Chenodeoxycholic acid Conjugation with glycine & taurine Sodium salts of conjugated acids
Average amount 3 to 4 gms in the body Only 5% excreted in faeces Powerful choleretics
Stimulus for Bile secretion Chemical Mechanism
Bile Salts Hormonal Mechanism
Secretin Neural Mechanism
Vagalstimulation
Gallbladder Site
Sac like structure Located beneath the liver
Functions Storage of bile Concentration of bile
Gallbladder Functions: Storage of bile Can store 450 ml of bile (12 hr of
secretion) Transported to the Gallbladder between
the meals
Gallbladder Functions: Concentration of bile Active transport of salts Water following osmotically Concentration of bile 5 to 10 times
Gallbladder : Emptying of Gallbladder Relaxation of sphincter of ODDI Contraction of gallbladder Role of cholecystokinin Stimulation by fatty foods in duodenum
Gallbladder : Formation of Gall stones Common site of formation of stones 75% of stones made of cholesterol 25% made of bilirubin In case of Gallbladder removal bile is
stored in common bile duct which becomes dilated
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