14.2 Basic Integumentary Concepts
Open Resources for Nursing (Open RN)
The integumentary system includes the skin, hair, and nails. The skin is an organ that performs a variety of essential functions, such as protecting the body from invasion by microorganisms, chemicals, and other environmental factors; preventing dehydration; acting as a sensory organ; modulating body temperature and electrolyte balance; and synthesizing vitamin D.[1]
Skin
The skin is made of multiple layers of cells and tissues, which are held to underlying structures by connective tissue. See Figure 14.1[2] for an image of the layers of the skin. The skin is composed of two main layers: the uppermost thin layer called the epidermis made of closely packed epithelial cells, and the inner thick layer called the dermis that houses blood vessels, hair follicles, sweat glands, and nerve fibers. Beneath the dermis lies the hypodermis that contains connective tissue and adipose tissue (stored fat) to connect the skin to the underlying bones and muscles. The skin acts as a sense organ because the epidermis, dermis, and hypodermis contain specialized sensory nerve structures that detect touch, surface temperature, and pain.[3]
The color of skin is created by pigments, including melanin, carotene, and hemoglobin. Melanin is produced by cells called melanocytes that are scattered throughout the epidermis. See Figure 14.2[4] for an illustration of melanin and melanocytes. When there is an irregular accumulation of melanocytes in the skin, freckles appear. Dark-skinned individuals produce more melanin than those with pale skin. Exposure to the UV rays of the sun or a tanning bed causes additional melanin to be manufactured and built up, resulting in the darkening of the skin referred to as a tan. Increased melanin accumulation protects the DNA of epidermal cells from UV ray damage, but it requires about ten days after initial sun exposure for melanin synthesis to peak. This is why pale-skinned individuals often suffer sunburns during initial exposure to the sun. Darker-skinned individuals can also get sunburns, but they are more protected from their existing melanin than pale-skinned individuals.[5]
Too much sun exposure can eventually lead to wrinkling due to the destruction of the cellular structure of the skin, and in severe cases, can cause DNA damage resulting in skin cancer. Moles are larger masses of melanocytes, and although most are benign, they should be monitored for changes that indicate the presence of skin cancer. See Figure 14.3[6] for an image of moles.
Patients are encouraged to use the ABCDE mnemonic to watch for signs of early-stage melanoma developing in moles. Consult a health care provider if you find these signs of melanoma when assessing a patient’s skin:
- Asymmetrical: The sides of the moles are not symmetrical
- Borders: The edges of the mole are irregular in shape
- Color: The color of the mole has various shades of brown or black
- Diameter: The mole is larger