Cracking your knuckles does not actually hurt your bones or cause arthritis. The sound you hear is just gas bubbles bursting.
18
When you get goosebumps and your hair stands, the hair helps to trap air, making you feel warmer by keeping in your body heat.
46
It would take about 1,200,000 mosquitoes to fully drain the average human body of blood.
217
Stress can result in more headaches as a result of the body rerouting blood flow to other parts of the body.
92
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
For most people, no matter how hard you pinch the skin on your elbow with your fingers it doesn't hurt.
515
Coughing can cause air to move through your windpipe faster than the speed of sound - over a thousand feet per second!
197
Oxygen, carbon, hydrogen and nitrogen make up 90% of the human body.
118