What happens when the pacemaker becomes nonfunctional ?

Options

A. Only auricles contract rhythmically
B. Only ventricles contract rhythmically
C. Cardiac muscles do not undergo co-ordinated rhythmic movements
D. Auricles and ventricles contract rhythmically

Answer

C

Explanation

The SA node possesses a unique property of self-excitation, which enables it to act as the pacemaker of heart. It spontaneously generates a wave of contraction which spreads over both the auricles more or less simultaneously along the muscle fibres that fan out from the pacemaker. The pacemaker establishes the basic rhythm at which the heart beats. Thus, if the pacemaker becomes nonfunction, then the cardiac muscles do not undergo co-ordinated rhythmic movements.