Skin Anatomy and Aging

The Three Layers of Skin

Human skin is composed of three layers: the epidermis, dermis, and subcutaneous tissue.


The epidermis is the skin’s outermost layer. This means it’s high in keratin, a protein that gives the skin toughness and water resistance. It is within this layer of skin that; dead skin cells are shed and where dark pigment called melanin is found. ​As the epidermis is the first line of defence in our body’s immune system, this acts as a barrier for the underlying layers.


The thick dermal layer lies beneath the epidermis. The dermis is composed of nerves, fats, blood vessels, elastin and collagen. Collagen is a protein that makes up the primary component of the body’s connective tissue, accounting for around 80% of the dermis. Collagen provides the skin with strength, whereas elastin gives you skin elasticity enabling it to stretch back and forth.

Subcutaneous Tissue:

The subcutaneous is the deepest layer of your skin. It is mostly comprised of fat. This layer acts as protection from internal organs and muscles. It also helps to keep us warm. Moreover, it provides your body with an energy reserve.

The structural changes that take place within these three layers of skin are responsible for producing the visible signs of aging. There are two different processes that induce such changes and lead to wrinkles. These are intrinsic aging and extrinsic aging.

Intrinsic Aging

Intrinsic aging, also known as chronological aging, occurs over the span of your life regardless of external factors. Intrinsic aging is a natural process, and although most bodies Intrinsic aging, also known as chronological aging, occurs throughout your life regardless of external factors. Intrinsic aging is a natural process, and although most bodies mature along a similar timeline, it varies from person to person based on heredity:

After age 20, our bodies produce 1% less collagen each year. The skin becomes inelastic and brittle as collagen and elastin fibres thicken and loosen; this is the skin’s attempt to stretch back and forth manifests as visible wrinkles. Exfoliation slows down in our 20s, causing dead skin cells to accumulate and stick together for longer periods of time.

In our 30s, the transfer of moisture between the dermis and epidermis slows and fat cells start to shrink, making the skin appear dull. As the body ages, the skin produces less In our 30s, the transfer of moisture between the dermis and epidermis slows and fat cells start to shrink, making the skin appear dull. As the body ages, the skin produces less sebum (oil). This causes the texture of the skin to become dry and for wrinkles to become more visible – which is why you might notice those Crow’s Feet around your eyes since this area has very few sebaceous glands.

Collagen production stops at age 40, and wrinkles form as the fibres begin to break and stiffen. Skin cell turnover slows, and it becomes more difficult for the cells to regenerate themselves.

By age 50, we start losing the fat stored in the subcutaneous tissue, making the skin thinner. In females, the loss of estrogen following menopause also contributes to thinness and results in the skin becoming more easily damaged. A decline in blood vessels and a decrease in circulation also works against our complexion.

All of these intrinsic factors contribute to wrinkles, sagging, and pigmentation issues. This aging process is very slow and only contributes to a small percentage of wrinkles. Most wrinkling is due to the effects of extrinsic aging.

Extrinsic Aging

Ever wake up one morning to be greeted in the mirror with a wrinkle that you swear wasn’t there the night before? It was most likely due to extrinsic aging. This type of aging refers to environmental influences that lead to wrinkles, and they’re responsible for creating the most dramatic signs of age. Here are a few of the most common sources of extrinsic aging.

Repeated facial expressions and sleeping positions:

When you smile, creases form at the corners of your mouth as your lips pull up into your cheeks. Such repeated facial expressions can eventually form wrinkles known as expression lines. While everyone should be proud of their signs of smiling, other expression lines are not so welcome. Be sure to be careful every time you rub those sleepy eyes in the morning, and try to switch up which side of your face you sleep on to reduce the risk of deepened creases along the side of your nose.


Stop smoking! It’s bad for your health and it’s what causes wrinkles on your face. Each time you take a drag from a cigarette, you’re pulling on what’s called your Purse String muscles. This repeated motion has the same effect as expression lines: premature wrinkles which betray your age. Furthermore, the nicotine found in cigarettes causes a narrowing of the blood cells within the outermost layer of the epidermis. If blood flow decreases, the skin becomes deprived of oxygen and vital nutrients, such as vitamin A. As a result, the skin begins to sag and wrinkle prematurely.


Free radicals (or harmful, electron-hungry molecules) cause damage when they pull electrons from other molecules in our bodies. This action alters chemical structures and biological functioning, thereby accelerating the aging process, as seen on our skin in the form of wrinkles. Pollution in the environment is a major source of free radical exposure, and although antioxidant enzymes can help protect against free radicals, their damage will occur regardless.

Exposure to the sun:

Photoaging, or changes that occur due to the sun, is by far the biggest culprit in the causation of wrinkles. The National Center for Biotechnology Information asserts that photoaging is responsible for 80 percent of wrinkles. When UVA rays penetrate deep into the skin’s dermal layer, it causes the breakdowns of our much-needed collagen and elastin. As these essential proteins break down, the skin begins to sag and wrinkle. Wrinkles are just one effect stemming from sun damage; photoaging also causes sun spots, rough texture, pigmentation problems, and can even lead to the development of deadly skin cancer.

Skin Aging Overview

The first wrinkles tend to appear on a person’s face in areas where the skin naturally folds during facial expressions. They develop due to the skin becoming thinner and less elastic over time.

Wrinkles also tend to appear on parts of the body that receive most sun exposure, such as the face and neck, back of the hands, and arms.

Wrinkles are a natural part of growing older, and they affect everyone. However, many people dislike the appearance of wrinkles, and, as a result, the anti-aging market in the United States is worth over 50 billion dollars per year.

How your skin ages will depend on a variety of factors: your lifestyle, diet, heredity, and other personal habits. For instance, are you a smoker or did you ever smoke? Smoking can produce free radicals, once-healthy oxygen molecules that are now overactive and unstable.

There are other reasons, too. Primary factors contributing to wrinkled, spotted skin include normal aging, exposure to the sun (photoaging), and loss of subcutaneous support (fatty tissue between your skin and muscle). Other factors that contribute to the aging of the skin include stress, gravity, daily facial movement, obesity, and even sleep position.

Wrinkles are a natural part of the aging process. As people get older, their skin becomes thinner, drier, and less elastic, which means it is less able to protect itself from damage. This leads to wrinkles, creases, and lines on the skin.

Facial expressions, such as smiling, frowning, or squinting, lead to the development of fine lines and wrinkles at a young age. These lines deepen as the person gets older.

When a person is young, their skin springs back. As they get older, the skin loses its flexibility, and it becomes more difficult for the skin to spring back, resulting in permanent grooves.

Wrinkles affect people of different skin tones differently due to structural and functional differences in the skin.

Many factors affect the development of wrinkles, including:

  • sun exposure
  • smoking
  • dehydration
  • some medications
  • environmental and genetic factors

Exposure to ultraviolet (UV) light from sunbathing, tanning booths, and outdoor sports increase the development of wrinkles.

UV light breaks down the collagen and elastin fibres in the skin. These fibres form the connective tissue that supports the skin. As this layer breaks down, the skin becomes weaker and less flexible. The skin starts to droop, and wrinkles appear.

Darker skin contains more melanin and protects from many harmful effects of UV radiation.

People who work in sunlight have a higher chance of early wrinkles. Wearing clothes that cover the skin, such as hats or long sleeves, may delay the development of wrinkles.

Regular smoking accelerates the aging process of the skin because it reduces the blood supply to the skin. Alcohol dehydrates the skin, and dry skin is more likely to develop wrinkles.

Skin Changes That Come With Age:

  • Skin becomes rougher.
  • Skin develops lesions such as benign tumors.
  • Skin becomes slack. The loss of the elastic tissue (elastin and collagen) in the skin with age causes the skin to hang loosely.
  • Skin becomes more transparent as we age. This is caused by thinning of the epidermis (surface layer of the skin).
  • Skin becomes more fragile as we age. This is caused by a flattening of the area where the epidermis and dermis (layer of skin under the epidermis) come together.
  • Skin becomes more easily bruised. This is due to thinner blood vessel walls as we age.