Discover how these two very important bodily systems work together to help keep us alive through a process called cellular respiration. A close-up look at the components of our blood: plasma, red blood cells, white blood cells, and platelets, demonstrates how critical blood is to our survival. Pumped by the heart through a vast network of vessels, our blood is the ultimate pick-up and delivery system, providing nutrients, carrying away harmful waste, and fighting against disease and infection.