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The average adult has about 21 square feet of skin.
When blood is exposed to air, it clots. Heparin allows the blood to come in direct contact with air without clotting.
If all the neurons in the human body were lined up, they would stretch more than 600 miles.
Most childhood vaccines are 90–99% effective in preventing disease. Side effects are rarely serious.
Thyroid conditions cause a higher risk of fibromyalgia and chronic fatigue syndrome.
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