The heart is divided into four chambers with two chambers on the right and two chambers on the left side. On each side, there are a chamber (atrium) and ventricle (ventricle) that work together to pump blood out into circulation. Chambers on the right-side pump's blood into the pulmonary circulation, and the chambers on the left-side pump's blood out into the wide circulation.
In connection with a single heartbeat does the two chambers on the same page as two pumps. First pull the smaller upper chambers together and fill the relaxed ventricles with blood. Immediately, after drawing the powerful chambers of the heart contracts and squeezes blood in cycles while the flaps are closed and the chambers fill with blood again. Effective circulation requires a rhythmic coordination of the upper chambers and the chambers of the heart to get the best possible pump effect.
In addition, it requires good control of the pulse, i.e., heartbeat rate, which is normally 60-100 beats per minute when the body is at rest. The coordination of these two mechanisms is performed through the heart's electrical system.