The discovery of blood circulation was made by which scientist?

Which chamber of the heart has the thickest wall?

Assertion : $Lub$ is a heart sound which is produced during each cardiac cycle.
Reason : It is associated with the closure of the tricuspid and bicuspid valves.

Mitral valve and tricuspid valve are attached to the papillary muscles by . . . . . . .

Cardiac output $= ......$

Choose the correct option: The $AV$ node / $SA$ node is called the pacemaker.