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CancerQuest > Introduction to Patient Information > Introduction to Cancer by Type > Introduction to Skin Cancer > Anatomy of the Skin

Anatomy of the Skin

The skin is one of the largest organs of the body⁽¹⁾ and is responsible for providing protection to the other systems of the body. Skin prevents water loss and dehydration, shields the internal organs in the event of injury, regulates body temperature, senses outside stimuli such as touch as well as heat and cold, and serves as a barrier to infection.⁽²⁾ As seen below, the skin is made up of three layers: the outer epidermis, the dermis and the deep subcutis layer. Other important elements of the skin include: hair follicles, sweat glands and nerve endings. Hair follicles protrude into the dermis layer and help regulate body temperature. Microscopic pores on the surface of the skin are connected to sweat glands which also help maintain homeostasis. Place your mouse over the labels to see the appropriate structure.

The pigments that color skin are produced by cells called melanocytes . Melanocytes, located in the epidermis (specifically in the stratum basale as seen in the diagram above), synthesize melanin which determines the color of the skin, hair and eyes.⁽³⁾ An individual's skin color is determined by their genes and their environment (primarily sun exposure). Our skin can change color in reaction to sun exposure. This is called the "tanning response." When skin absorbs UV radiation, melanin is produced and transferred to keratinocytes altering (darkening) the color of the skin.⁽⁴⁾Melanin in the skin absorbs and scatters UV radiation entering the body and helps protect the skin from adverse reactions to radiation, such as DNA damage (gene mutation). Viewed this way, the "tanning response" is really a defensive reaction by the body to the presence of damaging radiation.⁽³⁾

References for this page:

1. Goldsmith LA. My organ is bigger than your organ. Arch Dermatol. 1990 Mar;126(3):301-2. [PUBMED]
2. Vander's Human Physiology: The Mechanisms of Body Function, 10/e. Eric P. Widmaier, Hershel Raff, Kevin T. Strang. 2006. McGraw-Hill Inc: New York, New York.
3. Meredith P, Sarna T. "The physical and chemical properties of eumelanin." Pigment Cell Research. 2006 Dec; 19(6): 572-94. [PUBMED]
4. Tsatmali M, Ancans J, Thody AJ. "Melanocyte function and its control by melanocortin peptides." Journal of Histochemistry and Cytochemistry. 2002 Feb;50(2):125-33. [PUBMED]