electrical impulses

• what causes the heart to contract

  electrical impulses
• what does SAN stand for

  sino-atrial node
• what does AVN stand for

  atria-ventricular valve
• what are the stages of electrical impulse

  SAN releases wave of excitation

  atria contracts downwards

  AVN gathers wave of excitation causing a delay before sending down the septum

  ventricle contracts from the base upwards
• what does the wave of excitation travel via in the septum

  purkinje fibres

  bundles of hiz
• what is used to read the electrical impulses

  and ECG machine - electrocardiogram
• what causes the rate of electrical impulse to slow down

  impulses passed down along the vagus nerve (decelerator nerve)