Oxygen, carbon, hydrogen and nitrogen make up 90% of the human body.
118
Your thumb is about the same size as your nose.
124
Enamel is hardest substance in the human body.
61
For most people, no matter how hard you pinch the skin on your elbow with your fingers it doesn't hurt.
515
Dogs can be trained to identify the scent of lung cancer long before symptoms develop.
190
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
It takes about 20 seconds for a red blood cell to circle the whole body.
102