FACTS

1. The strongest muscle in the human body is the tongue and the hardest bone is the jawbone.

2. The human feet have 52 bones, accounting for one quarter of all the human body’s bones.

3. Feet have 500,000 sweat glands and can produce more than a pint of sweat a day.

4. The acid in your stomach is strong enough to dissolve razor blades. The reason it doesn’t eat away at your stomach is that the cells of your stomach wall renew themselves so frequently that you get a new stomach lining every three to four days.

5. The human lungs contain approximately 2,400 kilometres (1,500 mi) of airways and 300 to 500 million hollow cavities, having a total surface area ofabout 70 square metres, roughly the same area as one side of a tennis court. 
Also, your left lung is smaller than your right lung to make room
for your heart.