Skin

"The skin is the largest organ of the body, with a total area of about 20 square feet. The skin protects us from microbes and the elements, helps regulate body temperature, and permits the sensations of touch, heat, and cold.
Skin has three layers: The epidermis, the outermost layer of skin, provides a waterproof barrier and creates our skin tone.
The dermis, beneath the epidermis, contains tough connective tissue, hair follicles, and sweat glands.
The deeper subcutaneous tissue (hypodermis) is made of fat and connective tissue.
The skin’s color is created by special cells called melanocytes, which produce the pigment melanin. Melanocytes are located in the epidermis."

Scabies

Scabies is an easily spread skin disease caused by a very small species of mite. Scabies is found worldwide among people of all groups and ages. It is spread by direct contact with infected people, and less often by sharing clothing or bedding. Sometimes whole families are affected. Outbreaks of scabies are more common in nursing homes, nursing facilities, and child care centers. The mites that cause scabies burrow into the skin and deposit their eggs, forming a burrow that looks like a pencil mark. Eggs mature in 21 days. The itchy rash is an allergic response to the mite.