digestion, digestive enzymes and carbohydrate digestion

• absorption of nutrients happens in the small intestine its adapted by:

  • having villi and microvilli
  • villi have thin walls so shorter diffusion length
  • villi have lots of capillaries to help maintain concentration gradient by transporting absorbed nutrients away
  • villi contain muscles which help them mix the contents of ileum so they always have new nutrients to absorb
• the epithelial cells in the ileum are adapted by:

  • microvilli
  • many mitochondria to provide energy for active transport
  • carrier proteins for active transport
  • channel proteins for facilitated diffusion
• Amylase:

  • made in the salivary glands
  • breaks glycosidic bonds to hydrolyse starch to form maltose
• Pancreatic amylase:

  • made in the pancreas
  • breaks glycosidic bonds to hydrolyse starch to form maltose
• membrane bound disaccharidases:

  • found in the small intestine of the epithelial cells
  • breaks glycosidic bonds to hydrolyse disaccharides into monosaccharides
  • sucrase catalyses breakdown of sucrose into glucose and fructose
• maltase -> a-glucose
• sucrose -> glucose and fructose
• lactose -> glucose and galactose
• the ileum - the final section of small intestine where nutrients are absorbed into the blood stream , enzymes are secreted by glands in the walls
• digestive enzymes are needed to hydrolyse the food molecules
• polysaccharides and disaccharides are digested into monosaccharides by hydrolysis of glycosidic bonds
• glucose and galactose are actively transported using sodium ions through co-transporter proteins
• fructose is absorbed by facillated diffusion through a different transport protein