Give the location of the heart.

$A$ pacemaker is one that influences the

$SA$ 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?

Contraction of the right ventricle pumps blood into:

Define the following terms and give their location:
$(a)$ Purkinje fibres
$(b)$ Bundle of His

What is the function of papillary muscles?