Skin is an amazing organ. It covers the whole body and is capable of regeneration. The average adult has 8 pounds (3.6 kilograms) and 22 square feet (2 square meters) of skin [source: National Geographic]. In addition to its aesthetic role, skin functions as a temperature regulator, a shield against bacteria and water loss, a storage center for water and fat, and it allows us to feel the world around us.
While you may use the terms "thick-skinned" and "thin-skinned" to refer to a person's temperament, it's also true that we all have varying depths of skin on different parts of our bodies. The eyelids are the thinnest skin we possess, and because of their respective functions, the soles of the feet and the palms of the hands are thick.
Skin pigmentation resides in the epidermis, or the thin outer segment of the three layers that make up the skin. The epidermis alone is made up of three tiny sub-layers. Pigment does not reach the dermis, the middle layer of skin [source: University of Maryland Medical Center].
You get tan when your epidermis reacts to the ultraviolet (UV) rays of the sun. Your melanocytes get a message from your skin that says, "Hey, potential damage here. Protect me!" Melanocytes then produce more melanin, which protects skin from sun damage. Unfortunately, the body's natural protection is not enough to completely prevent damage and disease caused by the strong rays of the sun.
Continue to the next page to learn about things that can go wrong with your skin pigmentation.