Human heart and lungs. Animation showing the movement of the heart and lungs during normal breathing and the beating of the heart. The other internal organs are also shown. The right lung (red, upper left) has three lobes. The left lung (pink, upper right) has two lobes and a large cardiac impression where the heart (centre) is located. Below the heart and lungs is the diaphragm, a key structure in the breathing process. The lungs oxygenate the blood and remove carbon dioxide (produced as a waste gas by respiration in body cells). The heart pumps blood to the lungs and round the body. The main abdominal organs are also visible below the diaphragm: the liver, the stomach, and the intestines.