Question

With the help of a suitable diagram, describe the conducting system of the human heart.

Answer 1

1. The human heart is myogenic, which means that it may generate a cardiac contraction through specialised conducting (nodal) tissue.
2. The conducting (nodal) tissue is made up of the SA node (sino-atrial node), the AV node (atrioventricular node), and a bundle of His and Purkinje fibres.
3. The SA node is located in the right atrium at the superior vena cava entrance.
4. The SA node generates a contraction wave and sends it to the AV node and the left ventricle.
5. The AV node is located in the right atrial wall near the base of the interatrial septum and the coronary sinus entrance. The contraction wave is sent to both ventricles by the AV node.
6. A bundle of His branches begins at the AV node and travels along the interventricular septum. It divides into two branches, one for each ventricle.
7. These branches form a network in the ventricle walls. Purkinje fibres are the fibres found in these branches.
8. A bundle of His and Purkinje fibres transmits the contraction wave to both ventricles.