Your thumb is about the same size as your nose.
124
Cracking your knuckles does not actually hurt your bones or cause arthritis. The sound you hear is just gas bubbles bursting.
18
Staying awake for 17 hours is the same for your body as drinking 2 glasses of wine.
193
The adult human brain weighs about 3 pounds (1,300-1,400 g).
99
Oxygen, carbon, hydrogen and nitrogen make up 90% of the human body.
118
It takes about 20 seconds for a red blood cell to circle the whole body.
102
Your body is creating and killing about 2.4 million red blood cells per second.
17