Excerise

• When you exercise you respire more

  • muscles need energy from respiration to contract, when you exercise, some of your muscles contract more frequently than normal so you need more energy that comes from increased respiration.
• In exercise, your breathing rate and breath volume increase to get more oxygen into the blood, and your heart rate increases to get this oxygenated blood around the body faster. This removes carbon dioxide faster at the same time.
• When you do really vigorous exercise your body can't supply oxygen to your muscles quickly enough, so they start respiring anaerobically. This is not the best as lactic acid builds up which gets painful.
• Long periods of exercise can cause muscle fatigue- the muscles get tired and then stop contracting efficeintly.
• Anaerobic respiration leads to oxygen debt

  • Oxygen debt is the extra amount of oxygen your body needs to react with the build-up of lactic acid to remove it from the cells.
  • Oxygen and lactic acid react to form harmless carbon dioxide and water
• Oxygen debt means you have to 'repay' the oxygen that you didn't get to your muscles in time.
• Breathing hard for a while after stopping exercise is to attempt to get more oxygen into your blood and to the muscles cells as a result of oxygen debt.
• The pulse and breathing rate stay high whilst there are high levels of lactic acid and carbon dioxide.
• Your body has another way of coping with the high levels of lactic acid- the blood that enters your muscles transports the lactic acid to the liver. In the liver, the lactic acid is converted back into glucose.
• investigation of the effect of exercise.

  • measure breathing rate by counting breaths, and heart rate by taking the pulse
  • To take the pulse put two fingers on the inside of your wrist or your neck. Count the number of pulses in one minute.
  • Take your pulse after sitting down for 5 minutes, then after 5 minutes of walking, then after 5 minutes of slow jogging, then after 5 minutes of running. Plot the results in a graph
  • Pulse increases when doing intense exercise (your body needs to get more oxygen to the muscles).
  • do this as a group and plot an average pulse rate to reduce errors.