The lungs are vital for breathing. These tiny air sacs are located inside the chest and can cover an entire tennis court! The lungs are surrounded by ribs, which protect them and keep them from falling out. A muscle called the diaphragm lies below the lungs and helps them breathe in and out. A large number of the lungs are connected to the heart and the rest of the body, and a good working lung can help a person breathe easily and deeply.