Did you know that a red blood cell can make the return trip to your big toe in about 16 seconds? Did you know that if all your blood vessels were laid end to end, they would go around the world twice? Did you know that white blood cells are your body’s frontline defence against infection? Blood is your body’s lifeline. It delivers oxygen and nutrients to your cells and collects carbon dioxide and waste. Read all about your body’s amazing transport system in this volume of How My Body Works.