Digestion and Absorption 3.3.3

• Define digestion


  The hydrolysis of large, insoluble molecules into smaller molecules that can be absorbed across cell membranes
• Stages of digestion


  1. Ingestion - Food is taken in the body through the mouth2. Digestion - Breakdown of large, insoluble molecules into small, soluble molecules (by mechanical and chemical digestion)3. Absorption - The small, soluble molecules absorbed through the lining of the small intestine (ileum) into the blood4. Elimination - Any food that can't be digested is eliminated from the body
• Carbohydrate digestion

  
• Protein digestion

  
• Lipid digestion

  
• Enzymes involved in protein digestion

  • Endopeptidases = break between specific amino acids in the middle of a polypeptide • Exopeptidases- break between specific amino acids at the end of a polypeptide • Dipeptidases = break dipeptides into amino acids
• Ileum


  -the last and longest portion of the small intestine-contains embedded enzymes-where food is further digested (fat->micelles)

  
• Esophagus


  A muscular tube that connects the mouth to the stomach (pushes food via peristalsis)
• Absorption of amino acids and monosaccharides

  Diffusion and co-transport
• Absorption of fatty acids and monoglycerides

  1.Micelles contain bile salts and fatty acids and monoglycerides2. Make fatty acids and monoglycerides soluble3. Fatty acids and monoglycerides absorbed by diffusion4. Triglycerides formed 5. Vesicles move to cell membrane;

  
• Function of the large intestine

  Water and ion absorption