It takes about 20 seconds for a red blood cell to circle the whole body.
102
The adult human brain weighs about 3 pounds (1,300-1,400 g).
99
Our eyes are always the same size from birth, but our nose and ears never stop growing.
266
Dogs can be trained to identify the scent of lung cancer long before symptoms develop.
190
The human body contains over a billion miles of DNA.
147
Your body is creating and killing about 2.4 million red blood cells per second.
17
An average heart beats 100,000 times a day, pumping some 2,000 gallons of blood through its chambers. Over a 70-year life span, that adds up to more than 2.5 billion heartbeats.
73
Cracking your knuckles does not actually hurt your bones or cause arthritis. The sound you hear is just gas bubbles bursting.
18