The skin is the largest organ of the human body and provides a protective layer against heat, injury, and infection. The skin also assists in the synthesis of Vitamin D and stores fat and water. The average adult has 18 to 20 square feet of skin weighing approximately six pounds.
The skin is made up of three layers: subcutaneous layer, the dermis, and the epidermis. The epidermis is the outermost layer and protects against foreign bodies. The dermis contains hair follicles, oil glands, sweat glands, and capillaries. The subcutaneous contains large blood vessels and nerves and is responsible for conserving body heat.