Cracking your knuckles does not actually hurt your bones or cause arthritis. The sound you hear is just gas bubbles bursting.
18
Your thumb is about the same size as your nose.
124
Quick naps not only improve your alertness, but they also help in decision making, creativity and sensory perception.
149
It takes about 20 seconds for a red blood cell to circle the whole body.
102
Your heart will pump about 212 million liters in its lifetime.
26
Oxygen, carbon, hydrogen and nitrogen make up 90% of the human body.
118
The largest cell in the human body is the female egg and the smallest is the male sperm.
682
It would take about 1,200,000 mosquitoes to fully drain the average human body of blood.
217