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Location & extent

Location & extent . External Features . Porta Hepatis. Hepatic Segments/Physiological lobes. Blood Supply Hepatic artery Portal vein carries nutrients from the stomach and intestine to the liver (also from spleen). Portal vein divides into fine branches- into sinusoids.

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Location & extent

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  1. Location & extent Dr. S chakradhar

  2. External Features Dr. S chakradhar

  3. PortaHepatis Dr. S chakradhar

  4. Hepatic Segments/Physiological lobes Dr. S chakradhar

  5. Blood Supply • Hepatic artery • Portal vein carries nutrients from the stomach and intestine to the liver (also from spleen). Portal vein divides into fine branches- into sinusoids. Blood leaves sinusoids via hepatic vein to heart. Dr. S chakradhar

  6. Histology • Hepatic lobules Dr. S chakradhar

  7. Dr. S chakradhar

  8. Portal lobule: • This is the area of hepatic tissue between three adjacent central veins and centred on a portal canal with portal triads. • Is drawn by joining the central veins of the 3 adjacent liver lobules •  Area supplied by portal traid Dr. S chakradhar

  9. Portal acinus:/Liver Acinus • This is the area of hepatic tissue between the two adjacent central veins. This is metabolically the most active area. • Three zones are there: (i) Zone I (peri-portal) (ii) Zone II (intermediate) (iii) Zone III (near the central vein.) Dr. S chakradhar

  10. Dr. S chakradhar

  11. Functions of Liver Dr. S chakradhar

  12. Liver Functions Glucose metabolism • Important role in metabolism of glucose and regulation of blood glucose • Converts glucose to glycogen (storage) • Breaks down glycogen into glucose (energy) • Additional glucose is synthesized through gluconeogenesis (amino acids or lactate) Dr. S chakradhar

  13. Fat Metabolism • Fatty acids broken down into ketones • Provide source of energy for muscles and other tissues • Occurs when glucose is limited as in starvation or uncontrolled diabetes • Fatty acids also used for synthesis of cholesterol, lipoproteins and other complex lipids Dr. S chakradhar

  14. Protein metabolism In addition to synthetic function Protein catabolism & synthesis of urea formation Ammonia Conversion • Ammonia (potential toxin) is byproduct of gluconeogenesis • Liver converts ammonia into urea • Also removes ammonia produced by intestinal bacteria from portal blood • Urea is excreted in urine Dr. S chakradhar

  15. Synthetic function Synthesizes all plasma proteins except gamma globulin • Albumin (osmotic pressure) • Alpha and beta globulins • Blood clotting factors • Specific transport proteins • Prothrombin: liver needs vitamin K Dr. S chakradhar

  16. Bile Formation • Mainly water and electrolytes (potassium, calcium, bicarbonate, chloride) • Continuously made by hepatocytes and stored in gallbladder • Emptied into intestine when needed for digestion Bilirubin Excretion • Pigment derived from breakdown of hemoglobin • Modified by hepatocytes through conjugation to be more soluble in aqueous solutions • Conjugated bilirubin is carried by bile into duodenum for excretion Dr. S chakradhar

  17. Vitamin and Iron Storage • Vitamins A, D stored in liver • Iron and copper Drug Metabolism • Liver metabolism generally results in loss of activity of the medication • Certain oral meds absorbed by GI tract may be metabolized by liver to such a great extent (first-pass effect) that bioavailability is decreased Dr. S chakradhar

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