Enamel is hardest substance in the human body.
61
Coughing can cause air to move through your windpipe faster than the speed of sound - over a thousand feet per second!
197
Your thumb is about the same size as your nose.
124
Cracking your knuckles does not actually hurt your bones or cause arthritis. The sound you hear is just gas bubbles bursting.
18
Every year your body replaces 98% of your atoms.
119
When you take a step, you are using up to 200 muscles.
886
One human hair can support 3 ounces.
191
The largest cell in the human body is the female egg and the smallest is the male sperm.
682