Cracking your knuckles does not actually hurt your bones or cause arthritis. The sound you hear is just gas bubbles bursting.
18
When you take a step, you are using up to 200 muscles.
886
Your heart will pump about 212 million liters in its lifetime.
26
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
When you get goosebumps and your hair stands, the hair helps to trap air, making you feel warmer by keeping in your body heat.
46
One human hair can support 3 ounces.
191
Quick naps not only improve your alertness, but they also help in decision making, creativity and sensory perception.
149