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The familiar sounds of your heart are made by the heart's valves as they open and close.
Thyroid conditions cause a higher risk of fibromyalgia and chronic fatigue syndrome.
Sperm cells are so tiny that 400 to 500 million (400,000,000–500,000,000) of them fit onto 1 tsp.
The FDA recognizes 118 routes of administration.
In 1844, Charles Goodyear obtained the first patent for a rubber condom.
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