The Gastroenterology Teaching Project

Lipid Digestion

UTP 19

Table of Contents

  1. Definition of a Lipid
  2. Dietary Lipid Occurs in Three Physical Forms: Fat Droplets, Membranes, and Skin Lipids
  3. Fat (Mostly Triglyceride) is a Major Source of Calories in a Typical U.S. Diet
  4. Fat Droplets
  5. Average Daily Input of Lipids to the Gastrointestinal Tract of Western Man
  6. Bile is a Source of Endogenous Lipid and Detergent (Bile Salt)
  7. Fat Absorption is 98% Efficient Over a Wide Range
  8. The Composition of Fecal Fat in Normal U.S. Adults
  9. Neurohumoral Control of Digestive Secretions
  10. Release and Action of Cholecystokinin
  11. Steps in Troglyceride Absorption
  12. Triglyceride Digestion, Absorption, Resynthesis, and Secretion Occur Simultaneously
  13. Key Physicochemical Events in Lipid Digestion
  14. Multiple Lipases Assure Efficient Intraluminal Hydrolysis of Dietary Lipid
  15. Lipolytic Enzymes Act in Small Intestine at Micellar Bile Salt Concentrations
  16. Fat Absorption Persists in the Absence of Billary or Pancreatic Secretions
  17. The Relative Importance of Different Lipases for Triglyceride Digestion Chnages With Age
  18. The Relative Importance of Acid Lipases in Fat Digestion in Cases of Pancreatic Insufficiency
  19. Pancreatic Carboxyl Esterase Hydrolyzes a Variety of Lipid Esters
  20. Pancreatic Phopholipase A2 Hydrolyzes Membranes Phospholipids
  21. Differing Positional Specificity of Triglyceride Lipases
  22. Perferred Physical Forms of Substrates for Lipolytic Enzymes
  23. pH Optima of Gastrointestinal Lipases
  24. 10-30% Fat Digestion Occurs With Action of Acid Lipases in Stomach
  25. Fatty Acids Produced During Gastric Lipolysis Help Emulsify Fat in the Stomach
  26. Emulsification of Fat in the Stomach: Gastric Content Being Propelled Retrograde
  27. Fatty Acids Produced in Stomach Augment Duodenal Lipolysis by Multiple Mechanisms
  28. Properties of Pancreatic Lipase
  29. Effect of Bile Salts and Colipase on Pancreatic Lipase Activity
  30. Bile Salts Disperse the Products of Fat Hydrolysis
  31. Visible Product Ohases Can Be Seen During Fat Digestion on a Microscope Slide
  32. Fat Droplets Undergoing Digestion on a Microscope Slide
  33. The First Seconds of Lipolysis
  34. Bile Salts Disperse the Lipolytic Product Phases
  35. Bile Salts Solubilize Products of Lioplysis in Mixed Micelles
  36. Centrifugation of Intestinal Content Partially Separates the Phases Present During Fat Digestion
  37. Monomeric and Micellar Lipids and Bile Salts are in Dynamic Equilibrium
  38. Bile Salts Micelles Greatly Increase the Capacity of Water to Carry Fatty Acids
  39. Micellar Solubility of Lipolytic Products of Long Chain Triglyceride in Bile Salt Solution
  40. Intestinal Mixed Micelle Contains Bile Salts and Two Classes of Lipid Solute
  41. Micellar Solubilization of Secondary Solutes is Influenced by Multiple Factors
  42. Solubilized Dietary Fat Can Greatly Enhance Absorption of Otherwise Poorly Absorbed Secondary Micellar Solutes
  43. A Fluorescent Carcinogen Dissolved in Fat Moves into Product Phases During Lypolysis
  44. Unabsorbed Oils Trap Secondary Solutes and Reduce Their Absorption
  45. Plant Sterols Competitively Inhibit Cholesterol Solubility in Mixed Micelles
  46. Lipid Absorption is Limited by Slow Diffusion of Micelles and Individual Molecules Through the Unstirred Layer
  47. Unstirred Layer Thickness is Decreased by an Increase of Flow
  48. Effect of Micellar Solubilization of Fatty Acid on Diffusive Flux Through Unstirred Layer
  49. Possible Mechanisms of Membrane Transport of Fatty Acids
  50. Rate and Site of Fat Absorption is Modulated by Presence of Micelles
  51. Differing Sites and Mechanisms of Fat and Bile Salt Absorption
  52. The Luminal Face of the Intestinal Microvillus Membrane is Packed with Glycolipids and Cholesterol and Thereby Resistant to Digestion by Phopholipase A2
  53. Structure of the Microvillus Cytoskeleton Through Which Lipolytic Products Must Diffuse
  54. Luminal Contents During Fat Digestion
  55. Fatty Acid Binding Proteins May Assist in Intracellular Transport of Absorbed Fatty Acids
  56. High Intracellular Concentrations of Toxic Fatty Acids in Enterocyte Are Avoided By:
  57. Chylomicron Formation and Secretion
  58. Two Pathways of Triglyceride Synthesis in Intestine Insure Reesterfication of all Dietary Fatty Acid
  59. Structure and Composition of Chylomicron
  60. Chylomicrons Are Too Largeto Enet the Pores in Capillaries and Therefore Leave the Intestine Via the Lymphatic System
  61. Chylomicron Bypass Liver and Enter Systematic Circulation Via Thoracic Duct
  62. Digestion and Absorption of Medium Chain Triglyceride (MCT)
  63. Salad Oils May Contain Small Amounts pf Fat Soluble Carcinogens
  64. Fate of Fat Soluble Drugs and Xenobiotics is Influenced bby Biotransformation in Enterocytes
  65. Fate of Fat Soluble Drugs and Xenobiotics is Influenced bby Biotransformation in Enterocytes
  66. Newly Resynthesized Fat in the Intestine Conatins Fluorescent Molecules Originally Dissolved in the Dietary Fat
  67. Function of Intraluminal Bile Salts
  68. Physicochemical Properties of Conjugated Bile Salts Promote High Intraluminal Concentrations During Digestion
  69. Only Terminal Ileum Actively Absorbs Bile Salts
  70. Weakly Polar Molecules Are Passively Absorbed
  71. Important Differences Between Conjugated and Unconjugated Bile Salts
  72. Bile Salts Kinetics in Man
  73. High Aqueous Concentrations of Bile Salts and Fatty Acids in the Colon Are Toxic
  74. Multiple Factors Keep the Aqueous Concentration of Colonic Bile Salts Low
  75. Colonic pH Influences Physical State and Cathartic Activity Malabsorbed Bile Salts
  76. Bile Salt Malabsorption Causes Decreased Billary Secretion When Maximal Synthesis Cannot Compensate for Increased Loss
  77. Factors Causing Decreased Luminal Concentration of Mixed Micelles
  78. Different Intraluminal Defects Causr Fat Malabsorption
  79. Mechanisms of Fat Malabsorption
  80. Different Mucosal Defects Cause Fat Malabsorption
  81. Digestion of Triglycerides is Influenced by the Length of the Fatty Acid Chain
  82. Mucosal Processing and Body Metabolism of Fatty Acids Depends Upon Their Chain Length
  83. In Lipase Deficiency, There Are Few Lipolytic Products to be Solubilized by Bile Salts
  84. In Bile Salt Deficiency, Lipolytic Products Are Formed But Poorly Dispersed
  85. Fatty Acids Induce Net Fluid Secretion (Diarrhea)
  86. Non-Absorbed Dietary Fatty Acids Can Induce Colonic Fluid Secretion
  87. Causes of Impaired Triglyceride Hydrolysis
  88. There is Normally a Large Excess of Lipase Secreted for Fat Digestion
  89. Bile Salt Malabsorption Causes Progressive Bile Salt Deficiency Throughout the Day
  90. Consequences of Lipase Deficiency
  91. Consequences of Bile Salt Deficiency
  92. Steatorrhea After Ileal Resection is Influenced by Digestive and Absorptive Factors
  93. Solubilization of Lipolytic Products is Similar in Vitro and in Patients
  94. Dietary Oxalate Absorption is Enhanced and Prolonged in Patients with Steatorrhea Due to Bile Salt Deficiency
  95. Apparent Mechanism of Oxalate Hyperabsorption in Steatorrhea: Increased Oxalate Solubility and Increased Colonic Permeability
  96. Mechanisms of Diarrhea and Steatorrhea in Patients with Bile Salt Malabsorption
  97. Diarrhea Caused by Fat Malabsorption
  98. Unabsorbed Nutrients Are Metabolized by Enteric Flora
  99. Fat Balance is the Test for Steatorrhea
  100. Detection of Steatorrhea
  101. Detection of Bile Salt Malabsorption
  102. Treatment of Fat Malabsorption
  103. Diagnosis of Major Causes of Fat Malabsorption
  104. Low-Fat Diet Decreases Diarrhea in Patients eith Fat Malabsorption
  105. Characteristics of Bile Salt and Fatty Acid Diarrhea Afet Ileal Resection

 
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