Blood is amazing.
This fascinating liquid lifeforce is complicated in many ways and yet very simple at the same time, but what exactly is it, what does it do, and can we ever synthesise it in the lab?
Allan Doctor, Professor of Pediatrics at the University of Maryland School of Medicine and Director of the Center for Blood Oxygen Transport and Hemostasis joined Jonathan to discuss.
Also joining Jonathan for Newsround are Dr. Lara Dungan and Dr. Shane Bergin.