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Your skin wrinkles if you stay in the bathtub a long time because the outermost layer of skin (which consists of dead keratin) swells when it absorbs water. It is tightly attached to the skin below it, so it compensates for the increased area by wrinkling. This happens to the hands and feet because they have the thickest layer of dead keratin cells.
The familiar sounds of your heart are made by the heart's valves as they open and close.
More than 2,500 barbiturates have been synthesized. At the height of their popularity, about 50 were marketed for human use.
According to the Migraine Research Foundation, migraines are the third most prevalent illness in the world. Women are most affected (18%), followed by children of both sexes (10%), and men (6%).
Illicit drug use costs the United States approximately $181 billion every year.