digestion and absorption

• What does digestion involve?

  Hydrolysis of large insoluble molecules
• What are the three main types of molecules involved in digestion?

  Carbohydrates, lipids, and proteins
• What are the two enzymes mentioned for carbohydrate digestion?

  Amylase and membrane-bound disaccharidases
• Where is amylase produced?

  In the pancreas and salivary glands
• Where does carbohydrate digestion begin?

  In the mouth
• What happens to starch during carbohydrate digestion?

  It is hydrolyzed into disaccharides
• What is the role of membrane-bound disaccharidases?

  To hydrolyze disaccharides into monosaccharides
• What are the three types of enzymes that digest proteins?

  Endopeptidases, exopeptidases, and dipeptidases
• Where does protein digestion start?

  In the stomach
• What is the function of lipase?

  To hydrolyze ester bonds in triglycerides
• What is the role of bile salts in lipid digestion?

  To emulsify lipids into tiny droplets
• Where are bile salts produced and stored?

  Produced in the liver, stored in the gallbladder
• How does a larger surface area affect lipase action?

  More enzyme-substrate complexes form, speeding up action
• Why is emulsification advantageous for digestion?

  It increases surface area for faster hydrolysis
• What is a micelle?

  A sphere made of fatty acids and monoglycerides
• How do micelles aid in absorption?

  They deliver fatty acids to epithelial cells
• Where does absorption of digested food occur?

  In the cells lining the ileum
• What structures increase the surface area for absorption in the ileum?

  Villi and microvilli
• What is co-transport in absorption?

  A type of active transport for glucose and amino acids
• Why is co-transport essential for absorption?

  It helps absorb more sugar and amino acids
• How do lipids diffuse into epithelial cells?

  Due to their non-polar, lipid-soluble nature
• What happens to fatty acids inside epithelial cells?

  They are reformed into triglycerides
• What is a chylomicron?

  A triglyceride combined with a protein
• How are chylomicrons released from epithelial cells?

  By exocytosis
• Where do chylomicrons go after being released?

  Into the lacteal or lymph vessel
• How do lipids eventually enter the capillary system?

  Through drainage from the lymph vessels