Enamel is hardest substance in the human body.
61
It takes about 20 seconds for a red blood cell to circle the whole body.
102
Cracking your knuckles does not actually hurt your bones or cause arthritis. The sound you hear is just gas bubbles bursting.
18
Coughing can cause air to move through your windpipe faster than the speed of sound - over a thousand feet per second!
197
Yawns are more contagious among people with closer relationships.
163
Staying awake for 17 hours is the same for your body as drinking 2 glasses of wine.
193
The average person's skin weighs twice as much as their brain.
131
The adult human brain weighs about 3 pounds (1,300-1,400 g).
99