PATHOLOGY

Detailed explanation-1: -The SA node starts the sequence by causing the atrial muscles to contract. That’s why doctors sometimes call it the anatomical pacemaker. Next, the signal travels to the AV node, through the bundle of HIS, down the bundle branches, and through the Purkinje fibers, causing the ventricles to contract.

Detailed explanation-2: -The sinus node generates an electrical stimulus regularly, 60 to 100 times per minute under normal conditions. The atria are then activated. The electrical stimulus travels down through the conduction pathways and causes the heart’s ventricles to contract and pump out blood.

Detailed explanation-3: -The signal travels to the AV node (atrioventricular node). This node is between the atria and the ventricles. In the AV node, the impulses are slowed down for a very short time. This allows the atria to contract a fraction of a second before the ventricles.