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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.
The most destructive flu epidemic of all times in recorded history occurred in 1918, with approximately 20 million deaths worldwide.
In 1886, William Bates reported on the discovery of a substance produced by the adrenal gland that turned out to be epinephrine (adrenaline). In 1904, this drug was first artificially synthesized by Friedrich Stolz.
Blood is approximately twice as thick as water because of the cells and other components found in it.
The highest suicide rate in the United States is among people ages 65 years and older. Almost 15% of people in this age group commit suicide every year.