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
If you are cold you are more likely to be hungry because you use energy to keep warm.
143
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
Coughing can cause air to move through your windpipe faster than the speed of sound - over a thousand feet per second!
197
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