The Circulatory System
The Circulatory System is the main transportation and cooling system for the body. The Red Blood Cells act like billions of little UPS trucks carrying all sorts of packages that are needed by all the cells in the body. Instead of UPS, I'll call them RBC's. RBC's carry oxygen and nutrients to the cells. Every cell in the body requires oxygen to remain alive. Besides RBC's, there are also White Blood Cells moving in the circulatory system traffic. White Blood Cells are the paramedics, police and street cleaners of the circulatory system. Anytime we have a cold, a cut, or an infection the WBC's go to work.