The Sinuatrial Node (SAN, green), located at the roof of the right atrium close to the junction of the superior vena cava, acts as the "pacemaker" of the heart, spontaneously depolarizing at a certain rate influenced by the autonomous nervous system (sympathetic & parasympathetic).
The electrical impulse generated by SAN then travels through the atria. Three "atrial tracts" (green) are reported that connect to the Atrioventricular Node (AVN, blue). For the impulse to travel to the left atrium connections spanning the interatrial septum, base of the atria (coronary sinus) and the atrial roof (Bachman´s bundle) exist.
The AVN decrements conduction, thus exhibiting it´s gatekeeper function, protecting the ventricles from high rates.
Once past the AVN, the impulse travels via the bundle of His (purple) and then spreads into the bundle branches (green). The right bundle connects to the right ventricular apex, while the left bundle splices into a left anterior and left posterior bundle branch.
Bundle branches then connect to Purkinje fibers (purple). Purkinje fibers form a fine woven network, enabling conduction to the myocardium, producing the heart beat.
