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
Your thumb is about the same size as your nose.
124
It takes about 20 seconds for a red blood cell to circle the whole body.
102
After age 30, the brain begins to lose about 50,000 neurons per day - shrinking the brain .25% each year.
55
Coughing can cause air to move through your windpipe faster than the speed of sound - over a thousand feet per second!
197
Oxygen, carbon, hydrogen and nitrogen make up 90% of the human body.
118
Most of us have microscopic, worm like mites named Demodex that live in our eyelashes and have claws and a mouth.
-137