Effects of Aging

The skin tends to change throughout a person's lifetime. A baby's skin is very soft and smooth and provides a less effective barrier against harmful substances. A baby's skin has a much thicker fat layer and a much thinner layer of protective keratin. A young adult's skin is strong and supple. With age, the skin becomes thinner and finely wrinkled, with less underlying fat.

Aging itself results in thinning of the dermis and epidermis. Much of the underlying fat is lost as well, except on the thighs and abdomen, resulting in less insulation from cold. The skin loses some of its elasticity and becomes drier. The number of nerve endings in the skin decreases, so sensation is diminished. The number of sweat glands and blood vessels decreases as well, reducing the ability to respond to heat exposure. The number of melanocytes tends to decrease with age, so the skin has less protection against ultraviolet radiation. All of these changes make the skin both more susceptible to damage and slower to heal.

Sun damage produces many of the skin changes that people commonly associate with aging (see Section 18, Chapter 214). Long-term exposure to the ultraviolet radiation in sunlight is responsible for wrinkles, both fine and coarse; irregular pigmentation; brown and red spots; and the rough texture of sun-exposed skin.