The adult human brain weighs about 3 pounds (1,300-1,400 g).
99
For most people, no matter how hard you pinch the skin on your elbow with your fingers it doesn't hurt.
515
Cracking your knuckles does not actually hurt your bones or cause arthritis. The sound you hear is just gas bubbles bursting.
18
After age 30, the brain begins to lose about 50,000 neurons per day - shrinking the brain .25% each year.
55
It takes about 20 seconds for a red blood cell to circle the whole body.
102
One human hair can support 3 ounces.
191
Enamel is hardest substance in the human body.
61
Your body is creating and killing about 2.4 million red blood cells per second.
17