Electrocardiogram

• Depolarisation - neuron has an impulse travelling through it, causing contraction of muscle
• Repolarisation - neuron is resetting, relaxation of muscle
• Polarised - neuron is ready to send impulse, relaxation of muscle
• P wave

  • depolarisation of the atria
  • Contraction of the atria = atria systole

  
• QRS Complex

  • depolarisation of the ventricles
  • Contraction of the ventricles = ventricular systole

  
• T wave

  • repolarisation of the ventricles
  • Relaxation of the ventricles = ventricular diastole

  
• Changes in ECG traces

  • no clear P wave = problem with atrial contraction

  
• Changes in ECG traces

  • no clear QRS wave = problem with ventricular contraction

  
• Changes in ECG traces

  • distance between P wave is longer = decreased heart rate

  
• Changes in ECG traces

  • Distance between P waves is shorter = increased heart rate