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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?
Illicit drug use costs the United States approximately $181 billion every year.
Did you know?
Vaccines prevent between 2.5 and 4 million deaths every year.
Did you know?
The immune system needs 9.5 hours of sleep in total darkness to recharge completely.
Did you know?
Asthma cases in Americans are about 75% higher today than they were in 1980.