What are the roles of the sino atrial nodes?

Answer 1

the sinoatrial (SA) node is the "pacemaker" of the heart-it is the first stucture that makes up the conduction system of the heart-the system of electrical impulses that are discharged throughout the heart and cause rhythmic cardiac contractions and relaxations. impulse conduction starts in the SA node, causing the atria to contract, then goes to the atrioventricular (AV) node, the bundle of His, and then to the pukinje fibers which cause the ventricles to contract.