Monitoring Activity of the Heart

• Heart activity can be monitored by using an ECG, measuring pulse rate or listening to the sounds of valves closing using a stethoscop
• Heart rate (and pulse rate) is measured in beats per minute (bpm)
• To investigate the effects of exercise on heart rate, record the pulse rate at rest for a minute

  • Immediately after they do some exercise, record the pulse rate every minute until it returns to the resting rate
  • This experiment will show that during exercise the heart rate increases and may take several minutes to return to normal
• 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
• Breathing rate and pulse 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
• Increased physical activity results in an increased heart rate and breathing rate

  • Heart rate remains high for a period of time after physical has stopped, there is a gradual return to resting heart rate
• Effects of physical exercise - sufficient blood is taken to the working muscles to provide them with enough nutrients and oxygen for increased respiration

  • An increase in heart rate also allows for waste products to be removed at a faster rate
• Following exercise, the heart continues to beat faster for a while to ensure that all excess waste products are removed from muscle cells
• Muscle cells have been respiring anaerobically during exercise and so have built up an oxygen debt

  • This needs to be ‘repaid’ following exercise and so the heart continues to beat faster to ensure that extra oxygen is still being delivered to muscle cells
  • The extra oxygen is used to break down the lactic acid that has been built up in cells as a result of anaerobic respiration
• People who are more active have a lower resting heart rate
• You can listen to heart sounds using stethoscope to listen for valves
• ECG - checks how the heart is functioning

  • records how often heart beats
  • how regularly it beats