How does the cardiovascular (circulatory) system, respiratory system, and digestive system work?

These three systems work together in a collaborative manner. The respiratory system bring into the human system the oxygen that is needed for the cells to survive. This oxygen is transported around the whole body by the circulatory system. The circulatory system also removes the waste in the blood in form of carbon dioxide and give it unto the respiratory system to excrete. The digestive system also needs the circulatory system to transport the absorbed food nutrients round the whole body.