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Autoimmune diseases occur when the immune system destroys its own healthy tissues. When this occurs, white blood cells cannot distinguish between pathogens and normal cells.
Adolescents often feel clumsy during puberty because during this time of development, their hands and feet grow faster than their arms and legs do. The body is therefore out of proportion. One out of five adolescents actually experiences growing pains during this period.
More than 2,500 barbiturates have been synthesized. At the height of their popularity, about 50 were marketed for human use.
On average, someone in the United States has a stroke about every 40 seconds. This is about 795,000 people per 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.