Respiration

• Cellular respiration is an exothermic reaction which transfers energy from glucose and is continuously occurring in living cells
• Cellular respiration


  Breaking apart glucose molecules to release the energy that's trapped inside
• How organisms use their energy


  • Building up larger molecules from smaller ones (e.g. combining amino acids to form proteins)
  • Muscular contraction for movement
  • Maintaining body temperature
• Energy is needed for loads of reactions in our cells, most of which are catalyzed by enzymes
• Metabolism


  All the chemical processes that occur within a living organism in order to maintain life
• Aerobic respiration


  • More common type, takes place whenever there's enough oxygen, most efficient way to transfer energy from glucose, takes place continuously in both plants and animals, occurs within mitochondria
• Aerobic respiration


  Glucose + Oxygen → Carbon dioxide + Water
• The equation for aerobic respiration is the opposite of the equation for photosynthesis
• Anaerobic respiration


  • Respiration without oxygen, used when there is not enough oxygen to keep up with the demands of aerobic respiration, incomplete breakdown of glucose, leads to lactic acid buildup
• Anaerobic respiration


  Glucose → Lactic acid
• Anaerobic respiration in plants and yeast

  • Glucose is converted to ethanol and carbon dioxide instead of lactic acid, used in industry to make bread, beer, and wine
• Fermentation is the process of anaerobic respiration in yeast
• Exercise


  Requires increased aerobic respiration in the body
• Increased aerobic respiration during exercise


  1. Muscles require more energy

  2. Oxygen demand increases

  3. Breathing rate and volume increase

  4. Heart rate increases
• Insufficient oxygen during intense exercise

  Cells switch to anaerobic respiration
• Anaerobic respiration


  Less efficient than aerobic respiration, produces lactic acid
• Lactic acid buildup during exercise

  Causes a burning sensation in muscles
• Oxygen debt


  Extra oxygen needed after exercise to react with and remove lactic acid
• Removing lactic acid after exercise

  1. Lactic acid carried in blood to liver

  2. Reacted with oxygen to convert back to glucose
• Measuring effects of exercise

  • Breathing rate
  • Heart rate
• Breathing rate measured by counting chest rises and falls per minute
• Heart rate measured by taking pulse on wrist or neck artery
• Respiration


  Process by which organisms release energy to fuel their living processes
• Aerobic respiration


  • Uses glucose and oxygen
  • Releases energy
• Anaerobic respiration


  • Uses only glucose
  • Releases energy
• Aerobic respiration


  Glucose + oxygen → carbon dioxide + water + energy released
• Respiratory substrate


  Substance broken down by respiration to release energy
• Oxidise


  Chemical substances are oxidised by the addition of oxygen, removal of hydrogen or the removal of electrons
• Mitochondria


  • Structures in the cytoplasm of all cells where aerobic respiration takes place
• Anaerobic respiration


  • Occurs without oxygen
  • Produces lactic acid in human muscle
  • Produces ethanol and carbon dioxide in yeast and some plants
• Aerobic respiration


  • Complete oxidation of glucose
  • Relatively large amount of energy released
• Anaerobic respiration


  • Incomplete oxidation of glucose
  • Small amount of energy released quickly
• All organisms respire in order to release energy to fuel their living processes
• Respiration

  Can be aerobic, which uses glucose and oxygen, or anaerobic which uses only glucose
• Respiration releases energy - it is an exothermic reaction in which energy is given out to the surroundings
• Don't confuse respiration with photosynthesis. Photosynthesis is the process by which plants, and some bacteria, synthesise food molecules - which they then use, in addition to other things, for respiration
• Don't confuse respiration with breathing, which is ventilation (breathing in and out)
• Respiration happens in cells
• Why organisms need energy


  • To drive the chemical reactions needed to keep organisms alive
  • For movement
  • For cell division
  • To maintain constant conditions in cells and the body
  • For the transmission of nerve impulses
• Respiration is only around 40 per cent efficient