1. Respiratory brings oxygen and nutrients to the cells, while the circulatory
moves gases in and out of the blood. These work together because they have to exchange carbon dioxide and oxygen with each other.
2. The main parts and functions of the respiratory system are, the nose, pharynx, larynx, trachea, bronchi, and the lungs. As I said in the first answer, The respiratory brings oxygen and nutrients to the cells.
3. The main parts and functions of the circulatory system is the heart, lungs, arteries, veins, coronary, and portal vessels. The circulatory system moves gases in and out of the blood.
4. There are two main parts in your lungs, the pharynx, and the larynx. So, when you swallow food, the epiglottes blocks the entrance to these two main parts. Simply..if you could breath while doing this..I think you could die.
5. They are connected to capillaries that distribute blood to and from all the cells.