what structure initiates contraction in the heart
Conduction System. An electrical impulse travels through the heart and initiates contractions of the chambers. The heart's spark plug is an area of specialized heart tissue called the sinoatrial node (SA node) , which is located in the right atrium.lood that has traveled through the body returns to the heart and enters the right atrium. This blood flows through the tricuspid valve into the right ventricle. The right ventricle pumps the blood to the lungs, where it absorbs oxygen.