So when the left ventricle is relaxed, it accepts that blood from this left atrium. So valve number three is open, but valve number four, the aortic valve, is closed. But when contraction of the left ventricle takes place, number three closes. 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.