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Did you know?
The familiar sounds of your heart are made by the heart's valves as they open and close.
Did you know?
Human stomach acid is strong enough to dissolve small pieces of metal such as razor blades or staples.
Did you know?
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.
Did you know?
People with high total cholesterol have about two times the risk for heart disease as people with ideal levels.
Did you know?
Sperm cells are so tiny that 400 to 500 million (400,000,000–500,000,000) of them fit onto 1 tsp.