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The human body produces and destroys 15 million blood cells every second.
Vaccines prevent between 2.5 and 4 million deaths every year.
Cancer has been around as long as humankind, but only in the second half of the twentieth century did the number of cancer cases explode.
This year, an estimated 1.4 million Americans will have a new or recurrent heart attack.
The heart is located in the center of the chest, with part of it tipped slightly so that it taps against the left side of the chest.
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