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1. Your heart beats 65-80 times while you are resting, but, when exercising, it can reach up to 180 beats!
2. All of your veins, arteries, and capilaries, together, are MILES long, but they all fit inside your body!
3. Bone marrow produces red blood cells at a rate of 2 million red blood cells a second!
4. Some blood is actually blue! The blood that doesn't have oxygen!
5. New blood cells are made in the middle area of bones, called the marrow!
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