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There are more nerve cells in one human brain than there are stars in the Milky Way.
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).
This year, an estimated 1.4 million Americans will have a new or recurrent heart attack.
Many medications that are used to treat infertility are injected subcutaneously. This is easy to do using the anterior abdomen as the site of injection but avoiding the area directly around the belly button.
Blood is approximately twice as thick as water because of the cells and other components found in it.