Conducting system of heart consists of Sinoarterial (SA) Node, Internodal Pathway, Atrioventricular (AV) node, His Bundle. Bundle branches and Purkinje Fibers.
PACEMAKER POTENTIAL
Leakiness of Sinus Nodal fibers to Sodium and Calcium causes self-excitation.
Tenth of second after the action potential is over–> More Potassium channels close
The inward leaking Sodium (‘FUNNY CURRENT’) and Calcium ions once again overbalance the outward flux of Potassium ions –> Causes the resting potential to drift upward once more.
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
Concept Maps 