In the left side of the heart blood coming from the pulmonary circuit collects in the Left Atrium, the Left Atrium then contracts when it is full and blood flows through the Mitral Valve and into the Left Ventricle, then the Left Ventricle contracts when full and blood pushes though the Aortic Valve and on to the body at a high pressure so that is can rush to the parts of the body which the systemic circuit connects it to. Blood then coms back to the right side of the heart.
In the right side of the heart blood collects in the Right Atrium, when the Right Atrium is full it will contracts snd push the blood thought the Tricuspid Valve into the Right Ventricle, then the process begins again and once the Right Ventricle is full it will contract and push the blood thought the Pulmonic Valve and to the lungs to re-oxygenate and get ride of carbon dioxide, then it will go to the left side of the heart and the cycle begins again.
Reference
Childrens Heart Institute. (2015). Blood Flow Diagram. [Web portal]. Retrieved from http://www.childrensheartinstitute.org/content/blood-flow-diagram.html