And when the right pump relaxes, our left pump relaxes at the same exact time. So when the right ventricle contracts, the left ventricle contracts at the same time. Now, we know that inside our cardiovascular system the blood actually flows in only one direction. It's very important that the heart actually creates a unidirectional motion of blood. And to ensure that the blood doesn't actually flow backwards inside the heart we have a system of four different valves found inside our heart. So the heart must be able to pump blood in a unidirectional fashion.