Enamel is hardest substance in the human body.
61
Dogs can be trained to identify the scent of lung cancer long before symptoms develop.
190
Coughing can cause air to move through your windpipe faster than the speed of sound - over a thousand feet per second!
197
Our eyes are always the same size from birth, but our nose and ears never stop growing.
266
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
For most people, no matter how hard you pinch the skin on your elbow with your fingers it doesn't hurt.
515
If your DNA was stretched out it would reach to the moon 6,000 times.
256
The largest cell in the human body is the female egg and the smallest is the male sperm.
682