Digestion & absorption

Digestion & absorption

1. CARBOHYDRATES

   • Digestion
     • Enterocytes hydrolyze oligosaccharides and disaccharides to monosaccharides
   • Absorption
     • Fructose
       • Facilitated diffusion
       • By GLUT5
     • Glucose and galactose
       • Active transport
       • By SGLUT-1

2. LIPIDS

   • Digestion
     • Triacylglycerols get hydrolyzed by the lipases
       • Lingual and gastric lipases
         • They form 1,2-diacylglycerols and free fatty acids
       • Pancreatic lipase and colipase
         • Monoacylglycerols
           • 2-Monoacylglycerols lead triacylglycerols absorption
           • 1-Monoacyglycerols are hydrolyzed to fatty acids and glycerol
   • Absorption
     • They hydrolyze and bile salts permit emulsification
       • Micelles are soluble
         • They permit the transport to the enterocyte
           • They pass to the lymph and get the name of chylomicrons

3. PROTEINS

   • Absorption
     • Dipeptides and tripeptides get hydrolyzed into free amino acids
       • Got their absorption by active transport into the enterocytes
         • Tissue uptake
   • Digestion
     • Endopeptidases
       • Trypsin and chymotrypsin catalyze the hydrolysis of protein molecules to oligopeptides
       • Elastase digest the elastin from the proteine
     • Exopeptidases
       • Carboxypeptidases release amino acids from the free carboxyl terminal
       • Aminopeptidases release amino acids from the amino terminal

4. VITAMINS & MINERALS

   • Fat-soluble
     • Micelles
   • Water-soluble
     • Active transport
     • Facilitated diffusion
   • Vitamin D
     • Is required for the calcium absorption
   • Vitamin B12
     • Intrinsic factor
   • Iron
     • Enhanced by vitamin C and alcohol
     • Strictly regulated

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