Cracking your knuckles does not actually hurt your bones or cause arthritis. The sound you hear is just gas bubbles bursting.
18
Your body is creating and killing about 2.4 million red blood cells per second.
17
Staying awake for 17 hours is the same for your body as drinking 2 glasses of wine.
193
One human hair can support 3 ounces.
191
If your DNA was stretched out it would reach to the moon 6,000 times.
256
Coughing can cause air to move through your windpipe faster than the speed of sound - over a thousand feet per second!
197
It takes about 20 seconds for a red blood cell to circle the whole body.
102
There are times when you're walking that the pressure on your feet exceeds your body weight, and when you're running, it can be three or four times your weight.
62