Informacion adicional del pancreas
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  • 1. Pancreas• Gland with both exocrine and endocrine functions
  • 2. Histology-Exocrine Pancreas• 2 major components – acinar cells and ducts• Constitute 80% to 90% of the pancreatic mass• Acinar cells secrete the digestive enzymes• 20 to 40 acinar cells coalesce into a unit called the acinus• Centroacinar cell (2nd cell type in the acinus) is responsible for fluid and electrolyte secretion by the pancreas
  • 3. Histology-Exocrine Pancreas• Ductular system - network of conduits that carry the exocrine secretions into the duodenum• Acinus  small intercalated ducts  interlobular duct  pancreatic duct• Interlobular ducts contribute to fluid and electrolyte secretion along with the centroacinar cells
  • 4. Physiology – Exocrine Pancreas• Secretion of water and electrolytes originates in the centroacinar and intercalated duct cells• Pancreatic enzymes originate in the acinar cells• Final product is a colorless, odorless, and isosmotic alkaline fluid that contains digestive enzymes (amylase, lipase, and trypsinogen)
  • 5. Physiology – Exocrine Pancreas• 500 to 800 ml pancreatic fluid secreted per day• Alkaline pH results from secreted bicarbonate which serves to neutralize gastric acid and regulate the pH of the intestine• Enzymes digest carbohydrates, proteins, and fats
  • 6. Enzymes• Amylase – hydrolyzes starch and glycogen to glucose, maltose, maltotriose, and dextrins• Lipase – emulsify and hydrolyze fat in the presence of bile salts• Proteases – essential for protein digestion – secreted as proenzymes and require activation for proteolytic activity
  • 7. Histology-Endocrine Pancreas• Accounts for only 2% of the pancreatic mass• Nests of cells - islets of Langerhans• Four major cell types – Alpha (A) cells secrete glucagon – Beta (B) cells secrete insulin – Delta (D) cells secrete somatostatin – F cells secrete pancreatic polypeptide
  • 8. Histology- Islets of Langerhans• Contain the cells that secrete:• Glucagon - alpha cells, 20% of cells• Insulin - beta cells, 70% of cells• Somatostatin - delta cells, 5% of cells
  • 9. Endocrine Pancreas – Secretion is promoted by increased blood glucose levels – Stimulates the transport of glucose from the blood into muscle, liver and adipose tissue – Anabolic hormone • Synthesis of proteins, lipids, and nucleic acids9
  • 10. Endocrine Pancreas• Glucagon – Secretion is promoted by decreased blood glucose levels• Stimulates the release of Glucose by the liver• Catabolic hormone – Stimulates glycogenolysis, gluconeogenesis, and lipolysis• Somatostatin – Regulates alpha and beta cell secretions10