Purkinje fibers are located in the following structure/s:

Identify the correct statement.
$I$. The impulse of the heart beat originates from $SAN$.
$II$. Rate of the heart is determined by $SAN$.
$III$. Bundle of His/$AV$ bundle is present in the interventricular septum.
$IV$. Atrio Ventricular Node $(AVN)$ is situated in the lower left corner of the right auricle.
Choose the correct option.

............ can generate the maximum number of action potentials and is responsible for initiating and maintaining the rhythmic contractile activity of the heart. Therefore,it is called the pacemaker.

What is the correct sequence of the origin and conduction of the heartbeat?

The first heart sound occurs at:

Foramen ovale