Coronary sinus carries . . . . . . to the right atrium.

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.

How many times does the heart beat in one minute?

The thread-like tendons of papillary muscles inserted upon the flaps of tricuspid and bicuspid valves are:

The characteristic $Lubb-Dupp$ heart sounds are produced due to which of the following?

The heartbeat of a human is heard on the left side because: