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
When you take a step, you are using up to 200 muscles.
886
If you are cold you are more likely to be hungry because you use energy to keep warm.
143
Staying awake for 17 hours is the same for your body as drinking 2 glasses of wine.
193
Every year your body replaces 98% of your atoms.
119
Cracking your knuckles does not actually hurt your bones or cause arthritis. The sound you hear is just gas bubbles bursting.
18