Epidermal cells migrate from the basal layer to the surface of the skin where
cells die. Their cytoplasm is converted to keratin, which is the hard, rough tex-
ture that forms keratinocytes. Eventually keratinocytes slough off and new lay-
ers of epidermal cells migrate upward.
The dermis has two layers: the papillary layer, which is next to the epidermis;
and the reticular layer, which is the deeper layer of the dermis. Dermal layers are
comprised of fibroblasts, collagen fibers, and elastic fibers. Collagen and elastic
fibers give the skin strength and elasticity. The dermal layer contains sweat glands,
hair follicles, sebaceous glands, blood vessels, and sensory nerve terminals.
Subcutaneous tissue lies under the dermis and supports and protects the der-
mis. Subcutaneous tissue consists of fatty tissue, blood and lymphatic vessels,
nerve fibers, and elastic fibers.Skin Disorders
The skin is the site of several common disorders that include acne vulgaris,pso-
riasis, eczema dermatitis, contact dermatitis, drug-induced dermatitis, and burns.
Some disorders result from viral infections such as herpes simplexand herpes
zoster. Some result from fungal infections such as tinea pedis (athlete’sfoot) and
tinea capitis (ringworm).
Lesions may also appear on the skin as macules (flat with varying colors),
papules (raised, palpable, and less than 1 cm in diameter), vesicles (raised, filled
with fluid, and less than 1 cm in diameter), or plaques (hard, rough raised, and
flat on top).
Nearly all the disorders can be treated using mild or aggressive drug therapy
in the form of topical creams, ointments, pastes, lotions, and solutions—some of
which are available over the counter.ACNE VULGARIS
Acne vulgaris,commonly called acne, is inflammation of the pilosebaceous
glands. These are the glands which produce oil for the hair. Acne is more likely
to occur in adolescent males and is associated with testosterone level and the
ingestion of “greasy” foods—food containing trans-fatty acids (TFA). TFA are
synthetic alterations of naturally fatty acids and are present in processed foods,
candies, and potato chips.(^374) CHAPTER 20 Skin Disorders