Cracking your knuckles does not actually hurt your bones or cause arthritis. The sound you hear is just gas bubbles bursting.
18
It takes about 20 seconds for a red blood cell to circle the whole body.
102
Oxygen, carbon, hydrogen and nitrogen make up 90% of the human body.
118
The human brain uses approximately as much energy as a 10 watt light bulb.
120
The largest cell in the human body is the female egg and the smallest is the male sperm.
682
Yawns are more contagious among people with closer relationships.
163
It would take about 1,200,000 mosquitoes to fully drain the average human body of blood.
217
If you are cold you are more likely to be hungry because you use energy to keep warm.
143