The adult human brain weighs about 3 pounds (1,300-1,400 g).
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Your body is creating and killing about 2.4 million red blood cells per second.
17
Cracking your knuckles does not actually hurt your bones or cause arthritis. The sound you hear is just gas bubbles bursting.
18
It takes about 20 seconds for a red blood cell to circle the whole body.
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It takes twice as long to lose new muscle if you stop working out than it did to gain it.
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The human body contains over a billion miles of DNA.
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When you take a step, you are using up to 200 muscles.
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After age 30, the brain begins to lose about 50,000 neurons per day - shrinking the brain .25% each year.
55