APPLIED RADIOLOGICAL ANATOMY

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 two upper chambers are called atria (the right atrium and the left atrium), and the two lower chambers are called ventricles. Normally, the heartbeat starts in the right atrium in a group of special heart cells called the sinoatrial (or sinus) node. These cells act as a pacemaker for the heart.

Detailed explanation-3: -It is located at the junction of the crista terminalis in the upper wall of the right atrium and the opening of the superior vena cava. These cells have the ability to spontaneous generate an electrical impulse. It is the integrated activity of these so-called pacemaker cells that form the SA node.

Detailed explanation-4: -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.