Select the mismatched pair from the following.

Blood to the heart is brought by the venous system by:

$SA$ node (Sinoatrial node) ke baare mein sahi kathan chuniye:
$I$. Located at the right upper corner of the right atrium.
$II$. Heart of heart.
$III$. It initiates the rhythmic contractile activity of the heart.
$IV$. It is called the pace-keeper of the heart.
$V$. It is called the pacemaker of the heart.
Which of the following options contains the correct statements?

The first heart sound is

Draw a diagram of the human heart and label the $SAN$,$AVN$,$AV$ bundle,bundle of His,and Purkinje fibres.

Contraction of the right ventricle pumps blood into: