Since 2004, blood doping in cycling has dropped by 50 percent. The video opens with a narration about blood doping and then focuses on the structure of blood and how its parts work to keep the body alive. Classes learn about the structure and function of erythrocytes and hemoglobin and their roles in carrying oxygen in the blood as well red blood cell formation and their life cycle. The narrator wraps up the 30th installment of 47 by going back to doping, teaching how it works and how dangerous it can be.