Topic 2 - Organisation

• Digestive system processes


  • Stomach acid
  • Bile
  • Enzymes
• Enzymes


  Biological catalysts that are specific to certain substrates
• Practical: Enzyme activity


  1. Mix amylase and starch

  2. Test for starch every 10 seconds with iodine

  3. Plot time to complete reaction against temperature or pH

  4. Find optimum conditions
• Food tests


  • Iodine for starch
  • Benedict's solution for sugars
  • Biuret's reagent for proteins
  • Ethanol for lipids
• Breathing


  1. Air moves down trachea

  2. Into bronchi

  3. Bronchioles

  4. Alveoli
• Alveoli


  Have a large surface area for gas exchange
• Blood circulation


  1. Deoxygenated blood enters right atrium

  2. Pumped to lungs via pulmonary artery

  3. Oxygenated blood returns to left atrium

  4. Pumped to body via aorta
• Heart pacemaker


  Group of cells that create electrical pulses to make the heart contract
• Arteries


  Carry blood away from the heart, have thick walls
• Veins


  Carry blood towards the heart, have thin walls and valves
• Capillaries


  One cell thick walls for fast diffusion
• Coronary arteries supply the heart muscle with oxygen
• Stents


  Tubes inserted into blood vessels to keep them open
• Statins


  Drugs that reduce cholesterol
• Heart valve replacement


  Artificial valves can replace faulty ones
• Organisation


  Cell - Tissue - Organ - Organ System