Skin is considered an organ. The average person has 20 square feet of skin, making it the largest organ system of the human body. The total weight of human skin is about 9 pounds on average!
Skin cells are constantly shedding. It takes 60 days for replacement of all of your skin cells. The average person sheds 1 1/2 pounds of skin a year!
There are 625 sweat glands per square inch of human skin.
Skin color is due to melanin, which is a pigment produced in the epidermis layer to give protection from the sun’s ultraviolet (UV) rays. People who produce more numerous and deeper-colored melanin particles have darker skin. Darker skin is more common in tropical regions, where protection from the sun’s rays is more important. In northern regions, evolution led to lighter-skinned individuals, as the need for vitamin D, produced through exposure to UV rays of the sun, was more important.