The gross structure of the human heart and its associated blood vessels in relation to function.

The heart has four main areas: two atriums and two ventricles.

• Blood first enters the heart into the right atrium from the vena cava;
• passes through the right atrio-ventricular valve into the right ventricle;
• leaves through a semi-lunar valve into the pulmonary artery;
• goes past the lungs in capillaries where it is oxygenated;
• then re-enters the heart through the pulmonary vein into the left atrium;
• passes through the left atrio-ventricular valve into the left ventricle;
• then out through the left semi-lunar valve into the aorta (which takes it to the body.)

wikibooks

Veins always going into the heart and arteries away from it.
Atrium means entrance hall in latin.
Pulmonary means to do with the lungs.