Carbohydrates

• Carbs are mechanically digested by the teeth and in the stomach
• Amylase, maltase, lactase and sucrase are the enzymes involved in carb digestion
• Salivary amylase hydrolyses amylose into maltose
• Salivary amylase is produced pre-emptively
• Salivary amylase gets denatured by hydrochloric acid in the stomach
• Pancreas produces more amylase and other enzymes
• Membrane bound disaccharidases are stuck to the membrane in the small intestine and can be reused
• Carbs are hydrolysed into glucose and other monosaccharides
• Villi increase the SA in the small intestine
• Epithelial cells on surface of villi are covered in microvilli to further increase the SA
• There is only one cell between the gut lumen and the capillary- reduces diffusion distance
• constant blood flow in the capillaries maintains the concentration gradient
• Sodium glucose co-transport:

  1. active transport of sodium in to the blood
  2. creates low conc of sodium in epithelial cell
  3. co-transport (facilitated diffusion) of sodium and glucose along the conc grad into the epithelial cell
  4. facilitated diffusion of glucose into the blood
• Key organs in carb digestion:

  • mouth
  • salivary glands
  • pancreas
  • small intestine