ducts of pancreas no striated ducts intercalated ducts = intralobular ducts intercalated ducts drain...
TRANSCRIPT
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
Pancreatic Juice Secretion
• Secretin – Secreted in response to HCl– Produces HCO3-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
Gallbladder
• Hollow, pear-shaped organ attached to the lower surface of the liver
• Lies in gallbladder fossa
• Can store 30-50 mL of bile
Gallbladder
• Fundus• Body • Neck• Cystic duct
Gallbladder
• Main functions:– Stores bile– Concentrates bile (water absorption) – Releases bile when necessary into the digestive
tract
• Bile – fat emulsifier
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
Extrahepatic Bile Passages
• Hepatic ducts• Common hepatic duct• Cystic duct• Common bile duct
• Simple columnar epithelium
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
Liver
• Largest gland of body (approx. 1.5 kg)
• Right upper quadrant, under diaphragm
Liver
• Functions:– Produces bile: hepatic ducts → gallbladder– Synthesis: plasma proteins, hormones– Carbohydrate storage: glycogen– Detoxification and excretion of endogenous and
exogenous toxic substances
Liver
• Functions:– Eliminates particulate materials from blood
(phagocytosis)– Processes dietary amino acids, carbohydrates, lipids
and vitamins before they are released into general circulation
Glisson’s Capsule
• Thin fibroelastic capsule enclosing liver
• Covered with mesothelium
Blood Vessels
• Portal vein– Nutrient-rich blood from GIT → liver
• Hepatic artery– Supplies liver pareynchyma with arterial blood
• Enter through porta hepatis
Portal Triad
• Distinctive arrangement in a hepatic lobule• Consists of:– Hepatic artery– Hepatic portal vein– Bile duct
Portal Area
• Interlobular connective tissue + structures found in it (portal triad, lymphatic vessels, nerves)
Liver Architecture
Shape Model
Hepatic (classical) lobule
Polygonal Anatomical
Portal lobule Triangular (centered around portal triad)
Exocrine fxn (bile secretion)
Hepatic acinus Elliptical or diamond-shaped
Zone I (periportal)Zone II (transition zone)Zone III (centrilobular)
Blood flow and metabolic
Liver Cells
• Hepatocytes• Kupffer Cells
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
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