When the balloon of an intra-aortic balloon pump $(IABP)$ inflates,more blood is carried to:

Heartbeat can be initiated by

The opening between the right atrium and the right ventricle is guarded by . . . . . . .

The 'Bundle of His' is a muscular tissue found between:

$SA$ 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?

When do the 'lub' and 'dub' sounds occur during the cardiac cycle?
Lub $\quad$ $\quad$ $\quad$ Dub