Conducting system of heart consists of Sinoarterial (SA) Node, Internodal Pathway, Atrioventricular (AV) node, His Bundle. Bundle branches and Purkinje Fibers.

Conduction is Fastest in Purkinje Fibers. Depolarization initiated in SA node spreads radially through the atria.

INTERNODAL & INTERATRIAL PATHWAYS TRANSMIT CARDIAC IMPULSES THROUGH THE ATRIA
THE AV NODE DELAYS IMPULSE CONDUCTION FROM ATRIA TO VENTRICLES –
This delay allows time for atria to empty their blood into the ventricles before ventricular contraction begins. A-V node and its adjacent conductive fibers delay the transmission.

“Don’t be pushed around by the fears in your mind. Be led by the dreams in your heart.”
― Roy T. Bennett, The Light in the Heart