You’ve no doubt heard that the skin is the body’s largest organ, but at first glance it seems so different from other organs such as the heart, lungs, or kidneys. After all, your skin is on the outside, and even at its thickest it’s only about one-sixth of an inch thick. There’s a lot of it, however—about 22 square feet on an adult body, depending on height and girth—and weighing 8 pounds or more, skin is also the heaviest organ.
Like other organs, skin helps to keep the body safe and functioning—and not just by holding everything in. Your skin blocks germs and toxins, prevents dehydration, helps regulate your body temperature, and makes touch possible. Less obviously, the skin acts as a storage locker for fats, water, and products of metabolism. It’s also a factory for vitamin D when exposed to sunlight.
Skin is composed of three layers. The outer epidermis mostly consists of cells called keratinocytes, which constantly grow outward, die, and flake off, replaced by new cells. Next is the dermis, which houses sweat glands and hair follicles as well as nerves and capillaries. It is composed of collagen and elastin, the main structural scaffolding of the skin. At the base of the skin is the subcutis, an insulating fat layer.
Just as the heart, lungs, and kidneys can develop diseases or weaken with age, the skin is prone to problems ranging from dryness to cancer. Taking proper care of your skin, getting regular check-ups, and learning how to recognize possible problems can help keep your body’s largest organ hard at work.
The articles below cover many important ways you can protect your skin and some of the common things that can go wrong.