1. Ducts of Pancreas No striated ducts Intercalated ducts = intralobular ducts Intercalated ducts drain directly into interlobular ducts – simple squamous or low columnar epithelium Main pancreatic ducts (Wirsung and Santorini) – simple columnar epithelium

2. Pancreatic Juice Secretion Secretin – Secreted in response to HCl – Produces HCO 3 -rich secretion to neutralize acidic chyme (pancreatic enzymes function at optimal neutral pH) Cholecystokinin (CCK) – In response to the entry of proteins and fats – Enzyme-rich fluid which act mainly on extrusion of zymogen granules

4. Gallbladder Hollow, pear- shaped organ attached to the lower surface of the liver Lies in gallbladder fossa Can store 30-50 mL of bile

5. Gallbladder Fundus Body Neck Cystic duct

6. Gallbladder Main functions: – Stores bile – Concentrates bile (water absorption) – Releases bile when necessary into the digestive tract Bile – fat emulsifier

7. Gallbladder Wall Mucosa: – Have anastomosing folds, no villus – Simple columnar epithelium without goblet cells – Lamina propria Smooth muscle layer – stimulated by CCK Perimuscular connective tissue layer Serosa

10. Extrahepatic Bile Passages Hepatic ducts Common hepatic duct Cystic duct Common bile duct Simple columnar epithelium

12. Important Structures Ampulla of Vater (hepatopancreatic ampulla) – Formed by union of pancreatic duct and CBD Sphincter of Oddi – Muscular valve that controls the flow of digestive juices (bile and pancreatic juice) through the ampulla of Vater Major and minor duodenal papilla – Openings into the duodenum

14. Liver Largest gland of body (approx. 1.5 kg) Right upper quadrant, under diaphragm

16. Liver Functions: – Produces bile: hepatic ducts → gallbladder – Synthesis: plasma proteins, hormones – Carbohydrate storage: glycogen – Detoxification and excretion of endogenous and exogenous toxic substances

17. Liver Functions: – Eliminates particulate materials from blood (phagocytosis) – Processes dietary amino acids, carbohydrates, lipids and vitamins before they are released into general circulation

18. Glisson’s Capsule Thin fibroelastic capsule enclosing liver Covered with mesothelium

19. Blood Vessels Portal vein – Nutrient-rich blood from GIT → liver Hepatic artery – Supplies liver pareynchyma with arterial blood Enter through porta hepatis

21. Portal Triad Distinctive arrangement in a hepatic lobule Consists of: – Hepatic artery – Hepatic portal vein – Bile duct

24. Portal Area Interlobular connective tissue + structures found in it (portal triad, lymphatic vessels, nerves)

25. Liver Architecture ShapeModel Hepatic (classical) lobule PolygonalAnatomical Portal lobuleTriangular (centered around portal triad) Exocrine fxn (bile secretion) Hepatic acinusElliptical or diamond-shaped Zone I (periportal) Zone II (transition zone) Zone III (centrilobular) Blood flow and metabolic

33. Liver Cells Hepatocytes Kupffer Cells

34. Hepatocytes 80 % of cell population of liber Perform practically all metabolic and secretory functions Polygonal cells arranged in layer (hepatic plates) which anastomose with each other or with sinusoids Nuclei: 1 or 2, round, prominent nucleoli Cytoplasm: grainy, eosinophilic with many organelles

37. Kupffer Cells Fixed macrophages Remove old red blood cells from circulation and recycle their iron content Stellate shape (protoplasmic processes) Form the wall of hepatic sinusoids along with endothelial cells Nuclei: pale, vesicular