But number four, the aortic valve has to open to allow the movement of our blood into the systemic circulation of the cardiovascular system. So what can we conclude about these four valves? So basically, when relaxation takes place, valve number one and valve number three are open. These are the atrium ventricular valves. And they must be open to actually accept that blood from the atrium and into that ventricle. But when contraction takes place, the right and left atrial ventricular valves number one and three are actually closed.