Introduction

When people think about how their skin will change as they age, they are most often concerned about how it will look. They may fear that their skin will be dry, wrinkled, and covered with spots. Undeniably, the appearance of the skin changes as people age. But most unwanted changes in the skin's appearance are due to chronic sun damage, not to aging itself. Avoiding excessive sun exposure can prevent some of these changes or prevent them from worsening.

The skin is much more than just part of a person's appearance. It has many other functions, which can also be affected by aging. They include

• Protecting internal organs from physical and chemical injuries and from the sun's radiation
• Helping prevent viruses and bacteria from entering the body and helping defend the body against infection (the skin contains cells and substances of the immune system)
• Helping regulate the body's temperature by sweating and by insulating the body
• Helping regulate the body's temperature—tiny blood vessels in the skin expand (dilate) to release heat and narrow (constrict) to retain heat
• Forming vitamin D when the skin is exposed to sunlight
• Regulating the activity of many hormones and thus affecting some of the body's functions
• Regrowing and repairing itself to some degree when damaged
• Enabling people to know when the body touches something
• Enabling people to feel changes in temperature and to feel pain (sometimes warning them of danger)

See the figure Getting Into the Skin.

As people age, their skin changes in many ways. On the positive side, the skin tends to become less sensitive to substances that trigger allergic reactions, so allergic rashes become less common. On the negative side, the skin thins and becomes drier, less elastic, and more fragile. The skin gradually functions less well. It becomes less able to form vitamin D and to regulate the activity of hormones. Also, the sense of touch diminishes. For example, regulating body temperature and repairing damaged skin become more difficult. Thus, as people age, skin disorders become more common and bothersome.

The skin is the largest organ in the body. The skin varies in thickness depending on what part of the body it covers. The skin has several layers: epidermis, dermis, and subcutaneous fat layer. Each layer has a specific function.

For additional detail on this topic, see Layers of the Skin.

See the sidebar Skin Growths: Bumps and Spots.