Organisation

• Required Practicals


  • Food Tests
  • Effect of pH on the Rate of Reaction of Amylase
• 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 into the test tube

  2. Extract some of the amylase/starch solution after 10 seconds and place one drop into the first well of the spotting tile

  3. Continue to place one drop into the next well of the spotting tile, every 10 seconds, until the iodine remains orange

  4. Record the time taken for the starch to be completely digested by the amylase
• Effect of pH on the Rate of Reaction of Amylase

  1. Use the marker pen to label a test tube with the first value of pH buffer solution (pH 4) and stand it in the test tube rack

  2. Into each well of the spotting tiles, place a drop of iodine

  3. Measure 2cm3 of amylase and pour into the test tube

  4. Measure 1cm3 of the buffer solution and pour into the test tube

  5. Leave this to stand for five minutes and then use the thermometer to measure the temperature
• 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)
• Iodine is used to test for the presence of starch
• If starch is present, the colour will change to blue-black
• Cell


  The basic building blocks of all living things
• Tissue


  A group of cells with a similar structure and function
• Organ


  A combination of tissues carrying out a specific function
• Organ system


  Organs work together within an organ system
• Organism


  Organ systems work together to form whole living organisms
• Food Tests


  • sugar - Benedict's reagent (changes from blue-green to yellow-red)
  • starch - iodine (blue-black colour indicates presence)
  • protein - biuret (changes from blue to pink-purple)
  • lipid - sudan III (lipids separate and top layer turns bright red)
• The purpose of the digestive system is 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
• Enzyme


  A biological catalyst that speeds up chemical reactions without being changed or used up
• Active site


  The part of the enzyme where the substrate (reactants) fits
• Enzymes are very specific and will only catalyse one specific reaction
• Enzymes work optimally at specific conditions of pH and temperature
• In extremes of pH or temperature, the enzyme will denature and the active shape will deform</b>
• Enzymes and their substrates

  • amylase - starch (converts to sugars)
  • protease - protein (converts to amino acids)
  • lipase - lipid (converts to glycerol and fatty acids)
• Pulmonary circulation


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


  Serves the rest of the body and transports oxygen and nutrients from digestion to the cells, whilst carrying carbon dioxide and other waste away
• The systemic circulation flows through the whole body at a much higher pressure than the pulmonary circuit
• The products of digestion are used to build new carbohydrates and proteins, and some of the glucose is used for respiration
• Bile


  An alkaline substance produced in the liver and stored in the gall bladder, which neutralises stomach acid and emulsifies fats
• Emulsifying fats increases the surface area and rate of digestion by lipase
• Blood components


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

  
• Red blood cells


  Transport oxygen attached to haemoglobin, have a biconcave shape to increase surface area, and do not contain a nucleus

  
• White blood cells


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


  Important blood clotting factors
• Plasma


  Transports blood cells, carbon dioxide, nutrients, urea and hormones, and distributes heat
• Blood flow through the heart

  1. Deoxygenated blood enters right atrium via vena cava

  2. Pumped down through valves into right ventricle

  3. Forced up through pulmonary artery to lungs for gas exchange

  4. Oxygenated blood enters left atrium via pulmonary vein

  5. Down into left ventricle

  6. Pumped forcefully out of heart and around body via aorta
• Blood only flows in one direction due to valves in the heart
• Coronary heart disease


  Condition resulting from blockages in the coronary arteries that supply blood to the heart
• Lifestyle factors that increase risk of coronary heart disease

  • Diet high in saturated fat
  • Smoking
  • Stress
• Coronary heart disease is a major cause of many deaths in the UK and worldwide
• Symptoms can include chest pain, heart attack or heart failure, but not all people suffer the same symptoms
• Artificial pacemakers can be surgically implanted if the heart's natural pacemaker nodes are not functioning correctly