Cracking your knuckles does not actually hurt your bones or cause arthritis. The sound you hear is just gas bubbles bursting.
18
The human brain uses approximately as much energy as a 10 watt light bulb.
120
If every muscle in your body could pull in one direction, you could lift nearly 25 tons.
22
The largest cell in the human body is the female egg and the smallest is the male sperm.
682
Coughing can cause air to move through your windpipe faster than the speed of sound - over a thousand feet per second!
197
For most people, no matter how hard you pinch the skin on your elbow with your fingers it doesn't hurt.
515
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