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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.
More than 20 million Americans cite use of marijuana within the past 30 days, according to the National Survey on Drug Use and Health (NSDUH). More than 8 million admit to using it almost every day.
The familiar sounds of your heart are made by the heart's valves as they open and close.
Although the Roman numeral for the number 4 has always been taught to have been "IV," according to historians, the ancient Romans probably used "IIII" most of the time. This is partially backed up by the fact that early grandfather clocks displayed IIII for the number 4 instead of IV. Early clockmakers apparently thought that the IIII balanced out the VIII (used for the number 8) on the clock face and that it just looked better.