Lipid Digestion 021511 wo pics

Lipid Digestion 021511 wo pics - 1 L IPID D IGESTION...

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Unformatted text preview: 1 L IPID D IGESTION & A BSORPTION ( PG . 140-147) Lia M. Nightingale, Ph.D. LIPIDS IN OUR DIET Mainly TGs (~95%) Remaining 5%: Sterols (mainly cholesterol) Mostly as free cholesterol 10-15% are cholesterol esters Phospholipids Sterols & phospholipids TG CHOLESTEROLESTERS O 3 C = O Fatty acid LIPIDDIGESTION - MOUTH Lingual lipase released in mouth Activity decreases with age Most active in infants CH 2 O C R 1 R 2 C O CH CH 2 O C R 3 O O O sn-1 sn-2 sn-3 Removes sn-3 FA on TG containing short or medium chain FA Products of lingual lipase digestion: 1,2 DG & FA LIPIDDIGESTION - STOMACH Lipids are nonpolar need to be emulsified in order to allow digestion in stomach Shear of stomach churning helps mix Polysaccharides, phospholipids, digested proteins in chyme act as emulsifiers By which part of the stomach? LIPIDDIGESTION - STOMACH Gastric lipase released in stomach Together lingual lipase & gastric lipase digest ~20% of TG CH 2 O C R 1 R 2 C O CH CH 2 O C R 3 O O O sn-1 sn-2 sn-3 Removes sn-3 FA on TG containing short or medium chain FA Products of gastric lipase digestion: 1,2 DG & FA By which cells?? 2 LIPIDDIGESTION - STOMACH Presence of fat in stomach causes release of hormones that decrease gastric motility (gastric emptying) : CCK GIP GLP-1 Lipids have a high satiety value LIPIDDIGESTION - SI Chyme enters SI releasing: CCK Contracts pancreas Contracts gallbladder Secretin Contracts pancreas What is released? What is released? What is released? Made in liver from cholesterol Stored in the gallbladder BILE ACIDS HO OH OH COO- Cholic acid (cholate ) CONJUGATEDBILE ACIDS Bile acid + glycine C N CH 2 COO- Glycocholate O H glycine HO OH OH CONJUGATEDBILE ACIDS Bile acid + taurine C N CH 2 CH 2 SO 3- Taurocholate H taurine O HO OH OH BILE ACIDS & BILE SALTS Large lipid droplet Bile acids from gallbladder 3 LIPIDDIGESTION Micelles = fatty acids, monoglycerides, fat- soluble vitamins, cholesterol & bile salts B R U S H B O R D E R Unstirred water layer (UWL) PANCREATIC ZYMOGENS Colipase, Bile, Ca 2+ Trypsin Trypsin Procolipase Colipase Pancreatic lipase Active pancreatic lipase Prophospholipase A 2 Phospholipase A 2 Esterase Pancreatic lipases digest ~80% of TG ? PANCREATIC LIPASES IN SI Active pancreatic lipase Colipase Bile Ca 2+ CH 2 O C R 1 R 2 C O CH CH 2 O C R 3 O O O sn-1 sn-2 sn-3 Removes sn-1 & sn-3 FA on TG & DG Products of pancreatic lipase digestion: 2 MG & 2 FA PANCREATIC LIPASES IN SI CH 2 O C R 1 R 2 C O CH CH 2 O P O X O O O O- Phospholipase A 2 Removes sn-2 FA on phospholipid (mostly lecithin) Products of phospholipase A 2 digestion: FA & lysolecithin PANCREATIC LIPASES IN SI Esterase O 3 C = O Fatty acid Removes FA on cholesterol, Vitamins A & E Products of esterase digestion: FA & free compounds...
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This note was uploaded on 01/07/2012 for the course PHCH 51311 taught by Professor Nightingale during the Summer '11 term at Palmer Chiropractic.

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Lipid Digestion 021511 wo pics - 1 L IPID D IGESTION...

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