8. The 3 main parts of the circulatory system are the following, EXCEPT: A Heart B. Blood Vessels C. Blood D. Oxygen 9. This system is the control and coordinate system of the body. A. Respiratory system B. Circulatory system C. Digestive system D. Nervous system 10. What act as the building blocks of the entire nervous system? A. Cell B. Cell body C. Axon D. Dendrites​