B3 Organisation and the digestive system

• A tissue is a group of cells with a similar structure and function.
• An organ is a group of tissues working together to perform a specific function.
• The stomach contains muscle tissue and glandular tissue
• Lipases

  Break down lipids (fats) to glycerol and fatty acids
• Products of digestion

  1. Used to build new carbohydrates, lipids and proteins

  2. Some glucose is used in respiration
• Bile

  • Made in the liver and stored in the gall bladder
  • Alkaline to neutralise hydrochloric acid from the stomach
  • Emulsifies fat to form small droplets which increases the surface area
  • The alkaline conditions and large surface area increase the rate of fat breakdown by lipase
• Proteases

  break down proteins to amino acids
• Carbohydrases

  Breakdown carbohydrates (starch) to simple sugars. Amylase is a carbohydrase which breaks down starch
• Test for carbohydrates:

  • Starch

  indicator name : Iodine

  ❌ starch = stays orange

  ✅starch = blue-black
• Test for sugars:

  indicator name : Benedict’s solution

  ❌sugar = stays blue

  ✅ sugar = Brick red
• Test for protein:

  indicator name: Buriets solution

  ❌protein = stays blue

  ✅ protein = purple
• Test for lipids:

  indicator name: Sudan |||

  ❌lipids = stays red

  ✅lipids = red stained oil layer
• Digestive enzymes convert food into small soluble molecules that can be absorbed into the bloodstream
• Enzymes

  • enzymes are proteins
  • biological catalysts
  • don’t get used up in a biological reaction
  • made up of many amino acids folded into a protein
• Lock and key theory :

  1. The substrate fits into the active site (they are complementary)
  2. The enzyme splits substrate into two different substances
  3. The products leave active site
  4. ready to be used again
• AMYLASE

  produced in

  • Pancreas
  • small intestine
  • salivary glands

  works in

  • mouth
  • small intestine
• PROTEASE

  produced in

  • pancreas
  • small intestine
  • stomach

  works in

  • stomach
  • small intestines
• LIPASE

  produced in

  • pancreas
  • small intestine

  works in

  • small intestine