Question

Explain the conduction of the heartbeat.

[Review question: Pg. No: 215]

Answer 1

Initiation and conduction of Heart beat:

1. The human heart is myogenic in nature. Contraction is initiated by a specialized portion of the heart muscle, the sino-atrial (SA) node which is situated in the wall of the right atrium near the opening of the superior vena cava.
2. The SA node is broader at the top and tapering below. It is made up of thin fibres.
3. Sino-atrial node acts as the ‘pacemaker’ of the heart because it is capable of initiating impulse which can stimulate the heart muscles to contract.
4. The impulse from the sinoatrial node spreads as a wave of contraction over the right and left atrial wall pushing the blood through the atrioventricular valves into the ventricles.
5. The wave of contraction from SA node reaches the atrioventricular (AV) node which is stimulated to emit an impulse of contraction spreading to the ventricular muscle via the atrioventricular bundle and the Purkinje fibres.