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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.
Nearly 31 million adults in America have a total cholesterol level that is more than 240 mg per dL.
Hippocrates noted that blood separates into four differently colored liquids when removed from the body and examined: a pure red liquid mixed with white liquid material with a yellow-colored froth at the top and a black substance that settles underneath; he named these the four humors (for blood, phlegm, yellow bile, and black bile).
There are 60,000 miles of blood vessels in every adult human.
If all the neurons in the human body were lined up, they would stretch more than 600 miles.