Organisation

• Required Practicals


  • Food Tests
  • Effect of pH on the Rate of Reaction of Amylase
• Parts of the Digestive System

  • tongue
  • mouth
  • liver
  • gall bladder
  • small intestine
  • anus
  • salivary glands
  • oesophagus
  • stomach
  • pancreas
  • large intestine
  • rectum
• Food Tests


  1. Add 2cm3 of starch solution

  2. Extract some of the amylase/starch solution after 10 seconds

  3. Place one drop into the next well of the spotting tile every 10 seconds

  4. Record the time taken for the starch to be completely digested
• Iodine is used to test for the presence of starch. If starch is present, the colour will change to blue-black.
• Independent variable


  pH of the buffer solution
• Dependent variable


  Time taken for the reaction to complete (how long it takes for all the starch to be digested by the amylase)
• Effect of pH on the Rate of Reaction of Amylase

  1. Label a test tube with the first value of pH buffer solution

  2. Place a drop of iodine in each well of the spotting tiles

  3. Measure 2cm3 of amylase and 1cm3 of the buffer solution into the test tube

  4. Leave to stand for five minutes and measure the temperature
• Purpose of the digestive system

  To break down large molecules into smaller, soluble molecules, which are then absorbed into the bloodstream
• The rate of these reactions is increased by enzymes.
• Types of blood vessels

  • Artery
  • Vein
  • Capillary
• Capillaries


  • Narrow vessels which form networks to closely supply cells and organs
  • Walls are only one cell thick, which provides a short diffusion pathway to increase the rate at which substances are transferred
• Comparison of arteries and veins

  • Direction of blood flow
  • Oxygenated or deoxygenated blood
  • Pressure
  • Wall structure
  • Lumen (channel inside the vessel)

  
• Pulmonary circulation


  Serves the lungs and brings deoxygenated blood to exchange waste carbon dioxide gas for oxygen at the alveoli
• Systemic circulation


  Serves the rest of the body and transports oxygen and nutrients from digestion to the cells of the body, whilst carrying carbon dioxide and other waste away from the cells
• The systemic circulation flows through the whole body, so the blood is flowing at a much higher pressure than in the pulmonary circuit.
• Products of digestion


  • Used to build new carbohydrates and proteins
  • Some glucose used for respiration
• Bile


  • Alkaline substance produced in the liver and stored in the gall bladder
  • Neutralises the hydrochloric acid in the stomach
  • Emulsifies fats into small droplets to increase the rate of digestion by lipase
• Enzymes and their functions

  • Amylase - breaks down starch into sugars (glucose)
  • Protease - breaks down proteins into amino acids
  • Lipase - breaks down lipids into glycerol and fatty acids
• Enzyme


  Biological catalyst that speeds up chemical reactions without being changed or used up
• Enzyme active site


  The substrate (reactants) fits into this
• Enzyme specificity


  Enzymes will only catalyse one specific reaction
• Enzyme denaturation


  Bonds holding the 3D shape of the active site break, causing the active shape to deform, so the substrate can no longer fit
• Sino-atrial node (SAN)


  Located near the right atrium and stimulates the atria to contract
• The heart works as a double pump for two circulatory systems: the pulmonary circulation and the systemic circulation.
• Drugs (e.g. illegal drugs, alcohol) can lead to increased heart rate and blood pressure, increasing the risk of heart disease.
• Artificial pacemakers can be surgically implanted into a person if their heart nodes are not functioning correctly.
• Lifestyle factors that increase the risk of coronary heart disease

  • Diet high in saturated fat
  • Smoking
  • Stress
• Coronary heart disease


  Condition resulting from blockages in the coronary arteries, the main arteries which supply blood to the heart itself
• Coronary heart disease is a major cause of many deaths in the UK and around the world.
• Components of blood


  • Red blood cells (erythrocytes)
  • White blood cells
  • Platelets
  • Plasma

  
• Red blood cells


  • Transport oxygen attached to the haem group in their structure
  • Biconcave shape to increase surface area
  • No nucleus so can bind with more oxygen molecules

  
• White blood cells


  Form part of the immune system and ingest pathogens and produce antibodies
• Platelets


  Important blood clotting factors
• Blood flow through the heart

  1. Deoxygenated blood enters the right atrium via the vena cava

  2. Pumped down through the valves into the right ventricle

  3. Forced up through the pulmonary artery towards the lungs

  4. Oxygenated blood enters the left atrium via the pulmonary vein

  5. Down into the left ventricle

  6. Pumped out of the heart and around the body via the aorta
• The blood only flows in one direction due to valves in the heart which prevent backward flow.
• Cancer


  Result of uncontrolled cell growth and division, forming a tumour
• Leaves


  • Absorb sunlight energy for use in photosynthesis
  • Contain chloroplasts with chlorophyll to absorb sunlight
• Photosynthesis


  Carbon dioxide + water -> oxygen + glucose
• Left ventricle wall


  • Much thicker so it can pump the blood more forcefully out of the heart and around the entire body, via the aorta
• Blood flow in the heart

  Only flows in one direction because there are valves which close under pressure and prevent the backward flow of blood