How is blood pumped around the heart and to the body?

The pumping of the heart is split into two main phases, diastole (relaxation) and systole (contraction) and involves the four main chambers of the heart, the atria and ventricles, as well as the associated valves and blood vessels. Deoxygenated blood flows into the right atrium from the inferior and superior vena cava. The atria then contract (atrial systole) and blood is forced through the tricuspid valve into the right ventricle during ventricular diastole. The ventricle then contracts (ventricular systole) and blood is pushed through the pulmonary valve into the pulmonary artery and flows to the lungs. Blood is oxygenated at the lungs and returned to the heart via the pulmonary veins into the left atrium. Next the atria contract (atrial systole) and blood flows through the mitral valve from the left atrium into the left ventricle. The ventricles contract (ventricular systole) and blood flows out of the left ventricle through the aortic valve into the aorta and out to the rest of the body.