Skin

It's the largest organ of our bodies. It weighs about six pounds and holds us together. It's our skin.

Skin provides the outer covering for our bodies and protects us from heat, light, injury and infection. (Read about "Microorganisms") The skin regulates our body temperature by releasing fluids to cool us - in other words, sweat - and keeping heat in when it's cold. The skin also stores water and fat and produces vitamin D - all things we need to survive and live. (Read about "Vitamins & Minerals")

The skin is made up of two main layers, and an underlying layer:

• Epidermis - This is the main outer layer. The epidermis is mostly made up of flat scale-like cells called squamous cells. Under that are some round cells called basal cells. The deepest part of the epidermis also has what are called melanocytes. They produce melanin, which is what gives our skin its color.
• Dermis - Under the epidermis is the dermis, which contains the vessels for the blood and the lymph. It's also where the hair follicles and the glands are. Those glands are what produce sweat (to help cool us) and sebum, which is an oil that keeps the skin from drying out. Both oil and sweat get to the surface via the pores. The dermis also contains a binding protein called collagen.
• Subcutaneous tissue - Under the dermis is the subcutaneous tissue, which contains fat. This helps to keep us warm and provide cushioning.

There are a number of conditions that can change the look and the condition of the skin. Follow the links below to learn about them.