Cracking your knuckles does not actually hurt your bones or cause arthritis. The sound you hear is just gas bubbles bursting.
18
The largest cell in the human body is the female egg and the smallest is the male sperm.
682
Your body is creating and killing about 2.4 million red blood cells per second.
17
Your thumb is about the same size as your nose.
124
Enamel is hardest substance in the human body.
61
One human hair can support 3 ounces.
191
The human brain is very soft, having a consistency similar to soft gelatin or firm tofu.
13
Your heart will pump about 212 million liters in its lifetime.
26