CHAPTER 15

Human skin is the largest organ in the body, covering more than 20 square feet in an average adult. Skin thickness varies from one-fiftieth of an inch over the eyelids to one-third of an inch on the palms of the hands and soles of the feet. The pH of the skin ranges from 4.5 to 5.5, which provides the protective acid mantle that maintains the skin’s normal flora (1). The skin is made up of two layers—the dermis, which is the outermost layer, and the epidermis, the innermost layer (Figure 15.1). The epidermis consists of five distinct layers and regenerates itself every four to six weeks. The dermis consists of several components, including collagen, and contains nerve endings, blood vessels, lymphatics, capillaries, sweat and sebaceous glands, and hair follicles (1).

FUNCTIONS OF THE SKIN The skin’s major functions are the following (1):

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Protection: Skin protects the muscles, blood vessels, and organs by serving as a barrier to bacteria.

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Sensation: Pleasurable sensations like hugs of affection and unpleasant sensations like itching and pain are felt because of the nerve endings in the skin.

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Thermoregulation: Skin helps regulate body tem- perature by sweating to maintain homeostasis.

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Excretion: The end products of cell metabolism are excreted through the skin.

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Metabolism: Key metabolic functions include syn- thesizing vitamin D and playing a role in immune function such as allergic reactions.

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Communication: The appearance of the skin com- municates information about age and health.

Skin Integrity

CHANGES IN SKIN INTEGRITY ASSO-

CIATED WITH AGING The loss of skin elasticity, moisture, and reduced feeling (including ability to feel pain) in susceptible areas places older adults at risk for impaired skin integrity. Aging skin also loses thickness, making it more susceptible to mechanical trauma or break- down from pressure. With age, the skin is less able to manufacture vitamin D when exposed to sunlight. A decrease in pain perception associated with aging may make older adults more vulnerable to insults such as wearing tight shoes or tearing skin with routine care.

Figure 15.1 Normal Skin Epidermis

Dermis

Adipose Tissue

Muscle Bone

Source: Reprinted with permission from National Pressure Ulcer Advisory Panel. Pressure ulcer staging/category illustrations. www. npuap.org/resources/educational-and-clinical-resources/pressure- ulcer- categorystaging-illustrations/. Accessed January 25, 2016..