Lecture 11 - The Cellular Basis of Human Metabolism. Part 3 - Digestion and Absorption in the Inte

Lecture 11 - The Cellular Basis of Human Metabolism. Part 3 - Digestion and Absorption in the Inte

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1 The Cellular Basis of Human Metabolism. Part 3: Digestion and Absorption in the Intestinal Tract Biology 1F25 for Biology Non-Majors Lecture 11 Background Reading Textbook, Chapter 8 The People Who Prepared This Lecture Harry Peery Jeff Stuart The Duodenum
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2 First Problem: Protect against HCl If HCl from the stomach is not neutralized, it will eat holes in the intestinal tract. NOT GOOD! Brunner’s glands secrete copious amounts of mucus to protect the first part of the duodenum. Second Problem: Neutralize the HCl • In response to HCl, the intestinal hormone prosecretin is released by S cells into the intestinal lumen. – It is activated by HCl to become secretin – Secretin is absorbed through the intestinal wall and does the following: • It inhibits gastric secretion • It stimulates the production of a fluid high in NaHCO 3 (sodium bicarbonate) by the pancreas Relationship of Stomach, Pancreas and Liver Liver Gall Bladder Common bile duct Duodenum – 1 st part of small intestine Stomach Pancreas and pancreatic duct Spleen Left kidney Branch of hepatic portal vein coming from both stomach and pancreas
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3 Duodenum The pancreas The pancreas is both exocrine (secretes to a surface, in this case, to the intestinal lumen) and endocrine (secretion diffuses into the blood). The red arrow depicts an islet of Langerhans, whose endocrine cells secrete the hormones insulin, glucagon, and somatostatin. The dotted yellow line outlines the exocrine part of the pancreas, the acinus. The white arrow points out a central acinar cell. The green arrow points to a branch of the pancreatic duct, through which the exocrine part of the pancreas secretes fluids to the intestinal lumen Enzymes Enzymes The acinar cell spontaneously secretes a fluid high in sodium bicarbonate. The fluid is secreted into the central ductule of the acinus and from there into the pancreatic duct. The pancreatic duct may or may not join with the common bile duct. Both ducts empty into the duodenum Where did the pancreas get NaHCO 3 ? • Recall that in the production of HCl, by the
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This note was uploaded on 06/10/2008 for the course BIOL BIOL-1F25 taught by Professor Peery during the Spring '08 term at Brock University, Canada.

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Lecture 11 - The Cellular Basis of Human Metabolism. Part 3 - Digestion and Absorption in the Inte

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