For most people, no matter how hard you pinch the skin on your elbow with your fingers it doesn't hurt.
515
Enamel is hardest substance in the human body.
61
It takes about 20 seconds for a red blood cell to circle the whole body.
102
Every year your body replaces 98% of your atoms.
119
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
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