The circulation of blood was discovered by

The trilobed valve present between the right atrium and the right ventricle in the mammalian heart is known as:

The tricuspid valve is present at the origin of

Impulse originating from the sino-atrial node are transmitted to the

In the given diagram of the vertical section of the human heart,which label represents the papillary muscles?

Assertion : Muscle fibres of $SA$ node possess the lowest rhythmicity among all cardiac muscles.
Reason : Due to this fact,it can initiate excitatory waves at the highest rate.