"The circulatory system is the body's transportation highway. Arteries, veins and capillaries are like the major and local routes in the body's transportation system. In the respiratory system, as we take every breath, oxygen comes into our body. As we breathe out carbon dioxide, a waste product leaves our body so we can live and be healthy."
Veins are the freeways and capillaries
are the smaller side roads. The red blood cells move down these narrow local roads dropping off oxygen to the houses and people that live along those roads.
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