Cracking your knuckles does not actually hurt your bones or cause arthritis. The sound you hear is just gas bubbles bursting.
18
If every muscle in your body could pull in one direction, you could lift nearly 25 tons.
22
It takes about 20 seconds for a red blood cell to circle the whole body.
102
The human brain uses approximately as much energy as a 10 watt light bulb.
120
It takes twice as long to lose new muscle if you stop working out than it did to gain it.
127
It would take about 1,200,000 mosquitoes to fully drain the average human body of blood.
217
Your thumb is about the same size as your nose.
124
Our eyes are always the same size from birth, but our nose and ears never stop growing.
266