What is the path blood takes through the heart?

Blood enters the heart through the superior and inferior vena cava. These two paths dump deoxygenated blood into the right atrium. Blood passes from the right atrium through the tricuspid valve into the right ventricle. The right ventricle contracts and forces the blood through the pulmonary semilunar valve into the pulmonary arteries. The blood moves into the lungs and gas exchange occurs, oxygenating the blood. The blood then moves through the pulmonary vein, emptying into the left atrium. The oxygenated blood then passes through the bicuspid valve into the left ventricle. The left ventricle contracts and forces the blood out through the aortic semilunar valve and into the aorta. The aorta is the bodies largest artery and blood is distributed to smaller arteries and out to the entire body (except the lungs).

Remember simply:

Body -> Vena Cava -> Right Atrium -> Tricuspid Valve -> Right Ventricle -> Pulmonary Semilunar Valve -> Pulmonary Artery -> Lungs -> Pulmonary Vein -> Left Atrium -> Bicuspid (Mitral) Valve -> Left Ventricle -> Aortic Semilunar Valve -> Aorta -> Body

If you can remember this, remembering heart anatomy and understanding how the heart works is very simple.