How do the respiratory, circulatory, digestive and nervous systems work together to get essential materials to the cells of the body

Through the respiratory system oxygen is introduced into the body which is essential for the functioning of body cells. It also removes CO2 as waste from respiratory processes in cells. The digestive system breaks down food substances to form glucose and nutrients for cell functioning, heat generation etc. The circulation system in turn transports oxygen, sugars, nutrients as well as waste substances. The nervous system detects environmental and internal changes. It then takes the necessary measures manipulating the other systems to provide optimum functioning of the body.