Effects of aging
As aging occurs, the epidermis maintains its thickness, but there is a decreased turnover of cells. The dermis becomes thinner, the dermal papillae flatten, and the epidermis is held less tightly to the dermis so that the skin is looser. Adipose tissue in the subcutaneous layer of the face and hands also decreases, which means that older people are more likely to feel cold.
The fibers within the dermis change with age. The collagenous fibers become coarser, thicker, and farther apart; therefore, there is less collagen than before. Elastic fibers in the upper layer of the dermis are lost, and those in the lower dermis become thicker, less elastic, and disorganized. The skin wrinkles because (1) the epidermis is loose, (2) the fibers are fewer and those remaining are disorganized, and (3) the subcutaneous layer has less padding.
With aging, homeostatic adjustment to heat is limited because there is less vasculature (fewer blood vessels) and fewer sweat glands. The number of hair follicles decreases so that the hair on the scalp and extremities thins out. A reduced number of sebaceous glands results in the skin tending to crack.
As a person ages, the number of melanocytes decreases. This causes the hair to turn gray and the skin to become paler. In contrast, some of the remaining pigment cells are larger, and pigmented blotches appear in the skin.
Many of the changes that occur in the skin as a person ages appear to be due to sun damage. Ultraviolet radiation causes rough skin, mottled pigmentation, fine lines and wrinkles, deep furrows, numerous benign skin growths, and the various types of skin cancer.
