Michael Guista, Age 9, Of Exeter, Calif., For his question:

Haw does the heart get rid of its wastes?

The heart has its own blood vessel which connect with the blood stream of the body. Blood vessels carry oxygen to the heart from the lungs and dissolved food from the digestive system. These cells are changed into energy to keep the muscles of the heart pumping day and night. When the fuels are changed into energy, carbon diaxide and other waste chemicals are left over.

Blood vessels carry waste carbon dioxide from the heart to the lungs, and the lungs breathe it out into the air. Other waste chemicals from the heart enter the blood stream. They are carried to the kidneys and to other arrgans which get rid of the body's waste materials.