Question

Describe the conducting system of the human heart.

Answer 1

The heart possesses the property of autorhythmicity, which means it generates its own electrical impulses. Small groups of specialized neuromuscular cells in the myocardium initiate and conduct impulses.

Sinoatrial node (SA node):

It is a mass of specialized cells which lie in the wall of the right atrium near the opening of the superior vena cava. The sinoatrial cells generate regular impulses which cause atrial contraction. It normally sets the heart rate and is therefore called the pacemaker of our heart.

Atrioventricular node (AV node):

It is a small mass of neuromuscular tissue situated in the wall of the atrial septum near the atrioventricular valves. It carries the impulse generated by the SA node from the atria into the ventricles. It is known as the secondary pacemaker and takes over this role if the SA node is non-functional.

Atrioventricular Bundle (Bundle of His/ Purkinje Fibres):

It is a mass of specialized fibres which originate from the AV node. It transmits electrical impulses from the AV node to the apex of the myocardium where the wave of ventricular contraction begins.