Research shows that there are, in fact, two distinct types of aging. Aging caused by the genes we inherit is called intrinsic (internal) aging. The other type of aging is known as extrinsic (external) aging and is caused by environmental factors, such as exposure to the sun’s rays.
Intrinsic aging, also known as the natural aging process, is a continuous process that normally begins in our mid-20s. Within the skin, collagen production slows, and elastin, the substance that enables skin to snap back into place, has a bit less spring. Dead skin cells do not shed as quickly and turnover of new skin cells may decrease slightly. While these changes usually begin in our 20s, the signs of intrinsic aging are typically not visible for decades. The signs of intrinsic aging are:
- Fine wrinkles
- Thin and transparent skin
- Loss of underlying fat, leading to hollowed cheeks and eye sockets as well as noticeable loss of firmness on the hands and neck
- Bones shrink away from the skin due to bone loss, which causes sagging skin
- Dry skin that may itch
- Inability to sweat sufficiently to cool the skin
- Graying hair that eventually turns white
- Hair loss
- Unwanted hair
- Nail plate thins, the half moons disappear, and ridges develops
Genes control how quickly the normal aging process unfolds. Some notice those first gray hairs in their 20s; others do not see graying until their 40s. People with Werner’s syndrome, a rare inherited condition that rapidly accelerates the normal aging process, usually appear elderly in their 30s. Their hair can gray and thin considerably in their teens. Cataracts may appear in their 20s. The average life expectancy for people with Werner’s syndrome is 46 years of age.
A number of extrinsic, or external, factors often act together with the normal aging process to prematurely age our skin. Most premature aging is caused by sun exposure. Other external factors that prematurely age our skin are repetitive facial expressions, gravity, sleeping positions, and smoking.
A Fungus Is a Microorganism
Athlete's foot, or tinea pedis (say: tin-ee-uh peh-dus), is a common skin infection that is caused by a fungus (say: fun-gus), a plant-like microorganism (say: my-kro-or-guh-niz-um) too small to be seen by the naked eye. This fungus eats old skin cells. And plenty of them can be found on the feet!
Although athlete's foot occurs mostly among teen and young adult guys, kids and women can get it, too. People with sweaty or damp feet are at risk. Walking barefoot where others also walk barefoot is one way the fungus can get on your feet in the first place. That's why your mom or dad might say to wear your sandals when you're showering in a public shower.