Respiration

• Respiration principles

  • Cellular respiration is an exothermic reaction which is continuously occurring in living cells
  • The chemical process of cellular respiration releases energy
  • The energy transferred supplies all the energy needed for living processes to occur within cells and organisms as a whole
  • Organisms need energy for:
  • Chemical reactions to build larger molecules from smaller molecules
  • Muscle contraction to allow movement
  • Keeping warm (to maintain a constant temperature suitable for enzyme activity)
• what are uses of energy in the body?

  • maintenance of a constant body temperature
  • cell division and growth
  • active transport
  • passage of nerve impulses
  • muscle contraction
  • proteinsynthesis
• what is aerobic respiration?

  Process of producing energy from glucose in the presence of oxygen.
• Aerobic respiration

  • Respiration in cells can take place aerobically (using oxygen) to transfer energy; glucose is reacted with oxygen in this process
• What is the word equation for aerobic respiration?

  Glucose + Oxygen -> Carbon Dioxide + Water
• what's the symbol equation for aerobic respiration?

  C6H12O6 + 6O2 -> 6CO2 + 6H2O
• where does most of the reaction take place?

  in the mitochondria
• Anaerobic respiration in animals

  • Respiration in cells can take place anaerobically (without oxygen), to transfer energy; it simply involves the incomplete breakdown of glucose into lactic acid
  • This occurs when the body can’t supply enough oxygen for aerobic respiration, such as during vigorous exercise
  • As the oxidation of glucose is incomplete in anaerobic respiration much less energy is transferred than in aerobic respiration
  • Anaerobic respiration takes place without the need of oxygen
• what's the word equation for anaerobic respiration?

  Glucose → Lactic Acid (in muscles) or Ethanol + Carbon Dioxide (in yeast)
• anaerobic respiration in plants and yeast

  • Plants and yeast can respire without oxygen as well, breaking down glucose in the absence of oxygen to produce ethanol and carbon dioxide
  • Anaerobic respiration in yeast cells is called fermentation
  • Fermentation is economically important in the manufacture of bread (where the production of carbon dioxide makes dough rise) and alcoholic drinks (as ethanol is a type of alcohol)
• what's the equation for anaerobic respiration in yeast?

  glucose->alcohol+carbon dioxide
• oxygen in both respiration?

  • aerobic - needed
  • anaerobic -not needed
• does glucose breakdown in respiration?

  • aerobic - complete
  • anaerobic - incomplete
• what products do each respiration produce?

  • aerobic - carbon dioxide and water
  • anaerobic - animal cells: lactic acid and yeast: carbon dioxide and ethanol
• how much energy is released in respiration?

  • aerobic - a lot
  • anaerobic - a little
• what is cellular respiration?

  • it is not breathing; it is a chemical process of transferring energy from glucose in all living cells
• During exercise what are the cells doing?

  • the cells in the body are respiring more
• why do the cells in the body respire during exercise?

  because they require more oxygen and glucose to meet the energy demands of the cells and tissues
• what does the heart need to do during exercise?

  pumps at a fast rate to deliver oxygen and glucose via the blood
• what do the cells need as well as oxygen?

  glucose
• what needs to happen to the waste products?

  they need to be removed
• what will need to be removed from the lungs?

  • carbon dioxide and water
  • at a faster rate during exercise as they are produced more quickly than at rest
  • this is why the heart continues to beat faster after exercise has finished so the waste products can be removed
• what will the cells do when there is a lack of oxygen?

  • respire anaerobically
  • due to a lack of oxygen, which means an oxygen debt may build up
• what is an oxygen debt?

  an oxygen debt is repaying the oxygen that has been used up at a faster rate during exercise, this means the heart will continue to beat faster after exercise is finished, this is to deliver and replace the oxygen that has been used up so rapidly during exercise
• what is produced during anaerobic respiration in exercise?

  • lactic acid
  • extra oxygen is required for the breakdown of lactic acid
  • this is why we continue to breathe heavily after exercise
• An athlete takes part in vigorous exercise. After exercise has finished the athlete continues to breathe heavily for a few mins. Explain why

  1. anaerobic respiration takes place
  2. there is a build up of lactic acid
  3. lactic acid is broken down/oxidised by oxygen
  4. an oxygen debt builds up
  5. oxygen(used for the break down of lactic acid)has to be replaced so we breathe heavily
• What are the effects of exercise on heart rate?

  • heart rate is affected by exercise
  • increased heart rate during exercise ensures delivery of oxygen of oxygen and glucose to respiring cells
  • waste products need to be removed so the heart will continue to beat after exercise
  • anaerobic respiration may occur which produces lactic acid
  • oxygen is required to remove lactic acid which produces an "oxygen debt" so we continue to breathe heavily even after exercise has finished
• What is required for muscles to contract?

  Energy from respiration
• Why does exercise increase energy demand in muscles?

  Because the number of muscle contractions increases
• What happens to the heart rate during exercise?

  It increases
• What is the effect of increased heart rate during exercise?

  It increases oxygenated blood supply to muscles
• What is anaerobic respiration?

  Incomplete breakdown of glucose without oxygen
• What else must be removed from the body after vigorous exercise?

  Extra carbon dioxide
• What happens to muscles during long periods of vigorous activity?

  They become fatigued and stop contracting efficiently
• when exercising what do the muscles do?

  • When exercising, the number of muscle contractions increases, therefore there is a greater energy demand, which means that the muscles need a greater supply of oxygen for aerobic respiration
• how does the human body react to the increased demand for oxygen?

  • The breathing rate and breath volume increase during exercise to increase the amount of oxygen absorbed into the bloodstream by diffusion, and the amount of carbon dioxide removed
  • The heart rate increases
• Vigorous exercise

  • If exercising vigorously, the body may not be able to supply sufficient oxygen to the muscles to meet the demand for energy
  • In this situation, some of the energy supplied to the muscles comes from anaerobic respiration, which is the incomplete breakdown of glucose without oxygen
  • This releases much less energy than aerobic respiration and results in the formation of lactic acid as glucose is incompletely oxidised
• what is an oxygen debt?

  • An “oxygen debt” is created after exercising in this way; it is a debt as “extra” oxygen is needed to react with the lactic acid produced via anaerobic respiration
  • This is why an individual still breathes heavily at an increased rate (with a higher heart rate than usual) after exercising vigorously
  • “Extra” carbon dioxide also has to be removed from the body
• Investigating the effects of exercise

  • It is relatively simple to investigate the effects of exercise on the body in the classroom
  • Breathing rate can be measured by counting the number of breaths per minute, while heart rate can be measured by taking a pulse
  • Either can be measured before and after an activity is performed and the results plotted on a bar chart
  • It is important that the time over which breathing rate and pulse rate are measured is consistent, and that individuals fully recover (rest) before starting a new activity
• what happens in an oxygen debt?

  • The body can deal with lactic acid in one of two ways
  • It can be oxidised (reacted with oxygen) to form carbon dioxide and water – the same products formed in aerobic respiration
  • Alternatively, blood flowing through the muscles transports the lactic acid to the liver where it is converted back into glucose
  • Remember the “oxygen debt” is the amount of extra oxygen the body needs after exercise to react with the accumulated lactic acid and remove it from the cells