STARLINGS LAW

Starling's law of the heart

A statement in physiology: the strength of the heart's systolic contraction is directly proportional to its diastolic expansion with the result that under normal physiological conditions the heart pumps out of the right atrium all the blood returned to it without letting any back up in the veins.

To be honest I don't even know its a Starling but it's the only photo I've taken all day!