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When Gabriel Fahrenheit invented the first mercury thermometer, he called "zero degrees" the lowest temperature he was able to attain with a mixture of ice and salt. For the upper point of his scale, he used 96°, which he measured as normal human body temperature (we know it to be 98.6° today because of more accurate thermometers).
The familiar sounds of your heart are made by the heart's valves as they open and close.
It is important to read food labels and choose foods with low cholesterol and saturated trans fat. You should limit saturated fat to no higher than 6% of daily calories.
There are 20 feet of blood vessels in each square inch of human skin.
In the United States, there is a birth every 8 seconds, according to the U.S. Census Bureau's Population Clock.