Purkinje fibres are present in

$A$ : Left ventricle pumps blood at a much higher pressure to all body parts involved in systemic circulation.
$R$ : The muscular wall of the left ventricle is two to four times as thick as the wall of the right ventricle.

The heart continues beating normally even when its nervous supply is completely obliterated because it is

The cardiac impulse,which causes the heartbeat,is delayed in which of the following?

$A$ patch of nodal tissue responsible for initiating the rhythmic contractile activity of the heart is present in:

Cardiac muscles are .....