BioCoach Activity

Concept 3: Electrical Activity of the Heart

The heart's rhythm of contraction is controlled by the sinoatrial node (SA node), often called the pacemaker. This node is part of the heart's intrinsic conduction system, which is made up of specialized myocardial cells called nodal cells.

  • The heart will beat without input from the nervous system and will continue to beat, even outside the body, as long as its cells are alive.
  • The automatic nature of the heartbeat is referred to as automaticity.
  • Automaticity is due to the spontaneous electrical activity of the SA node. Electrical impulses generated from the SA node spread through the heart via a nodal tissue pathway that coordinates the events of the cardiac cycle.