Imagine your body as a giant city with its own superhighway. This superhighway is your circulatory system! At the heart of it all is your heart, working like a powerful engine. It pumps blood, which is like a fleet of trucks loaded with important cargo: oxygen and nutrients. The blood travels on roads called blood vessels. The highways are the arteries, carrying oxygen-filled blood from the heart to the city's farthest corners. The veins are smaller roads, carrying oxygen-depleted blood back to the heart. The red blood cells are like trucks carrying oxygen, and the white blood cells are like police cars, keeping us safe from harmful germs. Just like a city can't run without its superhighway, your body can't function without the circulatory system. It keeps you healthy and strong by delivering necessary supplies to every cell in your body!