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
For most people, no matter how hard you pinch the skin on your elbow with your fingers it doesn't hurt.
515
The average person's skin weighs twice as much as their brain.
131
Coughing can cause air to move through your windpipe faster than the speed of sound - over a thousand feet per second!
197
The largest cell in the human body is the female egg and the smallest is the male sperm.
682
An average heart beats 100,000 times a day, pumping some 2,000 gallons of blood through its chambers. Over a 70-year life span, that adds up to more than 2.5 billion heartbeats.
73
The human brain is very soft, having a consistency similar to soft gelatin or firm tofu.
13