The integumentary system consists of skin, hair, and nails.
Stem cell production declines with age, causing the epidermal cells to slow in their reproduction and, as a result, become larger and more irregular. This causes thinner, more translucent skin, meaning more frequent skin injuries, tearing, and infections. Coupling this with a combination of hormonal changes and alterations in lifestyle, the structure and chemical composition of many tissues will be affected.
The speed of healing takes more than twice as long in the elderly as it does in a much younger person. For example, it takes an average of three to four weeks for a blister to heal completely in a person age 18-25. The same tissue repairs in a person age 65-75 can take six to eight weeks, increasing the risk of secondary infections.
The ability to lose heat decreases as the blood supply to the dermis is reduced, as well as a reduction in sweat gland activity. This combination makes the elderly less able to lose internal body heat. Overexertion or overexposure to warm temperatures can cause dangerously high body temperatures. In addition, extreme temperatures of either heat or cold can be harmful, and special protective precautions must be taken during these times.
The number of macrophages and other cells of the immune system decreases to about 50% of the level seen at maturity. This loss causes further skin damage and risk of infections.
As melanocyte (pigment-producing cells) activity declines, there is decreased protection from ultraviolet light and a greater susceptibility to sunburn and skin cancer. This also causes the skin to become paler, and the hair to turn gray or white. In addition, selected melanocytes increase their production in areas exposed to the sun, resulting in brown spots on the skin.
Sebaceous gland activity declines as does sebum production. This causes perspiration to decrease, leaving the skin dry, scaly, and itchy.
The loss of fat and collagen in the underlying tissues causes the integument to weaken, producing skin sagging and wrinkling. The dermis becomes thinner and less elastic as the fiber network decreases in size, causing the skin to weaken and becomes less resilient. This becomes more pronounced in areas exposed to the sun, which also contributes to a decreased ability to maintain body temperature causing the person to feel cold.
As glandular activity declines, there is a reduction in the secretion of sebum (a waxy secretion that coats the surface of hairs). Perspiration production also declines. Both cause the skin to be dry and flaky.
Vascularity and circulation also decrease in the subcutaneous tissues, causing drugs that are administered in this manner to be absorbed more slowly.
Vascular supply to the nail bed decreases, resulting in dull, brittle, hard, and thick nails, with a slowed growth rate. The fingernails may flake and become brittle or develop ridges. The toenails may become discolored or abnormally thickened.
Cancers are more common in organs where stem cells divide to maintain epithelial cell populations. Rates of colon cancer and stomach cancer rise in the elderly, as well as oral and pharyngeal cancers in elderly smokers.