SC BIOL 244 - Digestive Organs Part 2 (3 pages)

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BIOM 121 1nd Edition Chapter 23 part 4 Lecture 4 September 2 Small Intestine Major organ of digestion and absorption From pyloric sphincter to ileocecal valve Subdivision Duodenum retroperitoneal The bile duct and main pancreatic duct Enter at the major duodenal papilla Controlled by the hepatopancreatic sphincter Jejunum Ileum Structural Modifications increase surface area of proximal part for nutrition absorption Circular folds Villi fingerlike projections of mucosa lined with simple columnar absorptive cells and Goblet cells Microvilli projections of absorptive cells bear brush border enzymes Submucosa Peyer s Patches protect distal part against bacteria Digestion Chime from stomach contains partially digested carbohydrates and proteins and undigested fats Slow delivery of hypertonic chime Delivery of bile enzymes bicarbonate from the liver and pancreas Mixing Liver Largest gland in the body 4 lobes right left caudate quadrate Falciform ligament Separates the larger right and smaller left lobes Suspends liver from the diaphragm and anterior abdominal wall Functions Hepatocyte Process blood borne nutrients Store fat soluble vitamins Perform detoxification Produce approx 900 ml bile per day Bile is yellowish alkaline solution containing Bile salts cholesterol derivatives that function in fat emulsification absorption Bilirubin pigment formed from heme Cholesterol neutral fats phospholipids electrolytes Gallbladder Thin walled muscular sac on the ventral surface of the liver Stores and concentrates bile by absorbing its water and ions Releases bile via the cystic duct which flows into the bile duct Pancreas Endocrine function Pancreatic islets secrete insulin and glucagon Exocrine function Acini clusters of secretory cells Secrete pancreatic juice Zymogen granules of secretory cells contain digestive enzymes Pancreatic juice watery alkaline solution pH 8 neutralizes chime Electrolytes HCO3 Enzymes Amylase lipases nucleases are secreted in active form but require