Your body is creating and killing about 2.4 million red blood cells per second.
17
It takes twice as long to lose new muscle if you stop working out than it did to gain it.
127
Cracking your knuckles does not actually hurt your bones or cause arthritis. The sound you hear is just gas bubbles bursting.
18
For most people, no matter how hard you pinch the skin on your elbow with your fingers it doesn't hurt.
515
The human brain uses approximately as much energy as a 10 watt light bulb.
120
The average person's skin weighs twice as much as their brain.
131
It takes about 20 seconds for a red blood cell to circle the whole body.
102
The largest cell in the human body is the female egg and the smallest is the male sperm.
682