Answer:The respiratory and circulatory systems work together to supply oxygen to the body and remove carbon dioxide. When you breathe in, the respiratory system brings oxygen into the lungs, where it moves into the blood. The circulatory system then carries this oxygen-rich blood to all parts of the body. After the cells use the oxygen, they produce carbon dioxide as waste, which the blood carries back to the lungs. Finally, the respiratory system removes the carbon dioxide from the body when you breathe out.