not mock (ECG)

• how can a doctor check someone's heart function

  using an electrocardiograph
• how does an electrocardiograph work

  The heart muscle depolarises (loses electrical charge) when it contracts, and repolarises (regains charge) when it relaxes. An electrocardiograph records these changes in electrical charge using electrodes placed on the chest.
• what is the P wave of an ECG caused by

  Contraction (depolarisation) of the atria
• what is the QRS complex on an ECG caused by

  contraction (depolarisation) of the ventricles
• what is the T wave on an ECG

  relaxation (repolarisation) of the ventricles
• what does the height of a wave indicate

  How much electrical charge is passing though the heart --> a bigger wave = more charge so for P and R waves, it means a stronger contraction
• what is a fast heartbeat called

  tachycardia
• when is a fast heartbeat normal

  during exercise
• what is a slow heartbeat called

  bradycardia
• what is an ectopic heartbeat

  extra beats caused by an earlier contraction of the atria or ventricles. occasional ectopic heartbeats in a healthy person don't cause a problem
• what is fibrillation

  A really irregular heartbeat. The atria or ventricles completely lose their rhythm and stop contracting properly. it can lead to chest pain, fainting or death
• why might athletes have bradycardia?

  they have larger stroke volumes so more blood is pumped with ebvery heartbeat so they need less beats