The Gastro-Intestinal System 3 (MPharm Programme) PDF

WEEK 15 MPharm Programme The Gastro-intestinal System 3 Dr G Boachie-Ansah [email protected] Dale 113 ext. 2617 MPharm PHA115 GI System  The Small Intestine...

WEEK 15 MPharm Programme The Gastro-intestinal System 3 Dr G Boachie-Ansah [email protected] Dale 113 ext. 2617 MPharm PHA115 GI System  The Small Intestine WEEK 15 Three Main Subdivisions Duodenum & Hepatopancreatic organs Fancreast galbladden Jejunum Ileum Slide 58 of 83 MPharm PHA115 GI System WEEK 15 The Duodenum & Hepatopancreatic Region Slide 59 of 83 MPharm PHA115 GI System  The Duodenum WEEK 15 The first 10 inches of small intestine ~ First site of intensive digestion Receives bile & pancreatic juice via the common bile duct & main pancreatic duct Arrival of chyme stimulates release of hepatic & pancreatic secretions fatty chyme in the duodenum  release of CCK  ∝ ? release of bile & pancreatic enzymes acid in chyme  release of secretin  release of pancreatic bicarbonate  neutralizes the acidity Slide 60 of 83 MPharm PHA115 GI System  Structure of the Pancreas WEEK 15 exocrire Celllscacte enymes ) tendocrine Cell act al. bicarkonate) (. Q ⑦ Slide 61 of 83 MPharm PHA115 GI System WEEK 15 Functional Anatomy of Pancreas 췌장 , Exocrine Duct cells secrete aqueous bicarbonate solution Acinar cells A → secrete pancreatic juice – proteases, amylase, lipase s me prolytic eny obotydrate oosaEcharide Endocrine tegrate protean s wo. Islets of Langerhans -cells – secrete insulin _ -cells – secrete glucagon Slide 62 of 83 MPharm PHA115 GI System  Secretions of the Pancreas WEEK 15 Slide 63 of 83 MPharm PHA115 GI System WEEK 15 Hormonal Control of Pancreatic Exocrine Secretion I Slide 64 of 83 MPharm PHA115 GI System WEEK 15 Activation of Pancreatic Enzymes enryme ( brush border) - mbedded In laminalmeembrae of thecellsthatine drodenal mucosa. ^ ⑦ 사 nhibstorto blick trypsan' s actans t pancreas poducetypsn Slide 65 of 83 MPharm PHA115 GI System WEEK 15 The Liver & Hepatic Portal Circulation fu dgestkre systen Niacsthg. Slide 66 of 83 MPharm PHA115 GI System  The Liver WEEK 15 The largest gland in the body Composed of ‘plates’ of liver cells (hepatocytes) main digestive function is the production of bile Bile a fat emulsifier a yellow-green, alkaline solution contains bile salts, bile pigments, cholesterol, ~ neutral fats, phospholipids & electrolytes stored & released from gallbladder Slide 67 of 83 MPharm PHA115 GI System WEEK 15 Fat Emulsification by Bile Salts " ↑ n ⑧ - Slide 68 of 83 MPharm PHA115 GI System WEEK 15 Control of Bile Release Slide 69 of 83 MPharm PHA115 GI System WEEK 15 Enterohepatic Circulation of Bile Salts ing " sttyags σ important ? Lidng 측면숙지 _ = Slide 70 of 83 MPharm PHA115 GI System WEEK 15 Digestion & Absorption in the Small Intestine Slide 71 of 83 MPharm PHA115 GI System WEEK 15 Absorption in Small Intestine Duodenum and jejunum main site of absorption freely absorb all products of carbohydrate, protein & fat digestion freely absorb most ingested electrolytes, vitamins & water absorption of calcium & iron is adjusted to the body’s needs ☆Ileum absorbs bile salts, vitamin B12, electrolytes & water Slide 72 of 83 MPharm PHA115 GI System WEEK 15 Carbohydrate, Protein & fat Digestion Slide 73 of 83 MPharm PHA115 GI System WEEK 15 Carbohydrate Digestion Slide 74 of 83 MPharm PHA115 GI System  Carbohydrate Absorption WEEK 15 Slide 75 of 83 MPharm PHA115 GI System  Protein Digestion WEEK 15 Slide 76 of 83 MPharm PHA115 GI System  Protein Absorption WEEK 15 Slide 77 of 83 MPharm PHA115 GI System WEEK 15 Fat Digestion and Absorption Slide 78 of 83 MPharm PHA115 GI System WEEK 1. Dietary fat in the form of large fat globules composed of triglycerides is 15 emulsified by the detergent action of bile salts into a suspension of smaller fat droplets. This lipid emulsion prevents the fat droplets from coalescing and thereby increases the surface area available for attack by pancreatic lipase. 2. Lipase hydrolyzes the triglycerides into monoglycerides and free fatty acids. 3. These water-insoluble products are carried to the luminal surface of the small-intestine epithelial cells within water-soluble micelles, which are formed by bile salts and other bile constituents. 4. When a micelle approaches the absorptive epithelial surface, the monoglycerides and fatty acids leave the micelle and passively diffuse through the lipid bilayer of the luminal membranes. 5. The monoglycerides and free fatty acids are resynthesized into triglycerides inside the epithelial cells. 6. These triglycerides aggregate and are coated with a layer of lipoprotein from the endoplasmic reticulum to form water-soluble chylomicrons. 7. Chylomicrons are extruded through the basal membrane of the cells by exocytosis. 8. Chylomicrons are unable to cross the basement membrane of capillaries, so instead they enter the lymphatic vessels, the central lacteals. Slide 79 of 83 MPharm PHA115 GI System  Iron Absorption WEEK 15 Slide 80 of 83 MPharm PHA115 GI System  The Large Intestine WEEK 15 Consists of the colon, caecum, appendix & rectum Primarily a drying & storage organ Minor absorptive function absorbs water, electrolytes, several vitamin B complexes, vitamin K & folic acid Contains many beneficial bacteria (~500 -1000 sp) L↳ produce vitamin K & folic acid ferment indigestible molecules to produce short-chain fatty acids Slide 81 of 83 MPharm PHA115 GI System  The Large Intestine WEEK 15 ↑ 「 δ Slide 82 of 83 MPharm PHA115 GI System WEEK 15 Recommended Reading Sherwood L. Human Physiology: From Cells to Systems, 9th ed. CENGAGE Learning (2015) ISBN: 978-1305273467 Sherwood L. Introduction to Human Physiology, 8th ed. Thomson Brooks/Cole/ CENGAGE Learning (2012) ISBN: 978-1133104544 VanPutte C et al. Seeley's Anatomy & Physiology, 13th ed. McGraw Hill (2022) ISBN: 978-1265129583 Slide 83 of 83 MPharm PHA115 GI System