Oxygen, carbon, hydrogen and nitrogen make up 90% of the human body.
118
Enamel is hardest substance in the human body.
61
Coughing can cause air to move through your windpipe faster than the speed of sound - over a thousand feet per second!
197
Your heart will pump about 212 million liters in its lifetime.
26
The average sperm cell swims at 8 inches per hour.
76
Your thumb is about the same size as your nose.
124
Cracking your knuckles does not actually hurt your bones or cause arthritis. The sound you hear is just gas bubbles bursting.
18