Which valve is located between the right atrium and the right ventricle?

Purkinje's fibres are special types of

Select the mismatched pair from the following.

The opening of the pulmonary vein is without a valve because

The histology of the heart superficially shows the following structures, $EXCEPT$:

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.