The total skin surface of an adult ranges from 12 to 20 square feet. In terms of chemical composition, the skin is about 70% water, 25% protein and 2% lipids. The remainder includes trace minerals, nucleic acids, glycosoaminoglycans, proteoglycans and numerous other chemicals.
Structure of the Skin
The skin consists of three main layers: Epidermis, Dermis and Hypodermis or subcutaneous.
- The outermost/top layer of the skin
- Has an average thickness of 0.1mm-1mm
- Avascular (no blood vessels)
- Divided into five sublayers: stratum corneum, stratum lucidum, stratum granulosum, stratum spinosum, and stratum germinativum (stratum basale)
- Contains four distinct layers of cells:
- a. Keratinocytes – Most abundant. Produces the protein keratin which provides mechanical and physical protection as well as producing enzymes and antibiotics that detoxify chemicals that are harmful to the skin
- b. Melanocytes – Produce melanin which imparts colour to skin and hair
- c. Merkel Cells – Play a role in transmission of sensory messages
- d. Langerhan Cells – Are essentially a forepost of the immune system in the epidermis. They prevent unwanted foreign substances from penetrating the skin
- On a daily basis dead skin cells are shed by the epidermis in a process called Keratinization (also known as the skin-renewal process) which takes approximately 4 weeks. However, as you mature, the process slows down and takes longer to complete. When the Keratinization Process begins to slow, the skin has a tendency to hold on to more dead cells, rendering the skin dull and lifeless.
- The condition of epidermis determines how “fresh” your skin looks and also how well your skin absorbs and holds moisture. Wrinkles, however, are formed in lower layers.
- Immediately below the epidermis
- Largest portion of the skin
- Composed of two layers:
– Lies directly below the epidermis and contains fibroblasts (play a critical role in wound healing) that form collagen (a component of connective tissue responsible for the structural support)
– The proper function of fibroblasts is highly important in overall skin health.
– Lies beneath the papillary layer and produces collagen and elastin (A protein in connective tissue that is elastic and is responsible for the resilience of the skin)
- Made up of blood and lymph vessels, nerves, sweat and sebaceous glands, and hair roots
- Provides tensile strength, mechanical support and protection to the underlying muscles, bones, and organs
- Responsible for the skin’s structural integrity, elasticity and resilience.
- Wrinkles arise and develop in the dermis. Therefore, an anti-wrinkle treatment has a chance to succeed only if it can reach as deep as the dermis.
- Often referred to as true skin
- Innermost layer of the skin
- Composed of fat, blood vessels, and connective tissue
- Sweat glands and minute muscles attached to hair follicles originate here
- Anchors to deep tissue
- Regulates body and skin temperature
- Stores energy in the form of fat
- The loss of subcutaneous tissue, often occurring with age, leads to facial sag and accentuates wrinkles.
Function of the Skin
- Facilitates perception of environment – pain, pressure, touch, and temperature
- Provides a barrier against friction, chemicals, heat/cold, pressure, radiation, and micro-organisms
- Plays a role in fluid balance, thermal regulation, and facilitates in Vitamin D synthesis
Aging of our Skin
There are 2 distinct types of aging: intrinsic and extrinsic.
Intrinsic aging is known as the natural aging process. It is a continuous process that normally begins in our mid-20s but the effects are typically not visible for decades.
In Intrinsic aging of the skin:
- Collagen production slows and elastin, the substance that enables skin to snap back into place, has a little less spring.
- Dead skin cells do not shed so quickly and turnover of new skin cells may decrease slightly.
The signs of intrinsic aging are:
- Fine wrinkles
- Thin & transparent skin
- Loss of underlying fat, leading to hollowed cheeks and eye sockets as well as noticeable loss of firmness on the neck and hands
- 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
- Greying hair that eventually turns white
- Hair loss
- Unwanted hair
In extrinsic aging, 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.
Causes of External Aging
The Sun – Without protection from the sun’s rays, just a few minutes of exposure each day over the years can cause noticeable changes to the skin. Freckles, age spots, spider veins on the face, rough leathery skin, fine wrinkles that disappear when stretched, loose skin, a blotchy complexion, actinic keratoses (thick wart-like, rough, reddish patches of skin), and skin cancer can all be traced to sun exposure.
The sun also attacks our elastin. Sun-weakened skin ceases to spring back much earlier than skin protected from UV rays. Skin also becomes loose, wrinkled and leathery much earlier with unprotected exposure to sunlight. Premature aging from years of unprotected exposure to the sun causes deep wrinkles, age spots and leathery skin.
People who live in sun-intense areas can show signs of photoaging in their 20s. While it may seem that the signs of photoaging appear overnight, they actually lie invisible beneath the surface of the skin for years.
Facial Expressions – Repetitive facial movements lead to fine lines and wrinkles. Each time we use a facial muscle, a groove forms beneath the surface of the skin, which is why we see lines form with each facial expression. As skin ages and loses its elasticity, the skin stops springing back to its line-free state.
Gravity – Gravity constantly pulls at our bodies. Changes related to gravity become more pronounced as we age. In our 50s, when the skin’s elasticity declines dramatically, the effects of gravity become evident.
Sleeping Positions – Resting your face on the pillow in the same way every night for years on end also leads to wrinkles. Called sleep lines, these wrinkles eventually become etched on the surface of the skin and no longer disappear when the head is not resting on the pillow. People who sleep on their backs do not develop these wrinkles since their skin does not lie crumpled against the pillow.
Smoking – smoking causes biochemical changes in our bodies that accelerate aging. Research shows that a person who smokes 10 or more cigarettes a day for a minimum of 10 years is statistically more likely to develop deeply wrinkled, leathery skin than a non-smoker.
While the intrinsic aging process cannot be stopped, you can prevent signs of premature aging (extrinsic aging) by protecting your skin from the sun, quitting smoking and eliminating facial expressions. Less stress, exercise and a good diet are also helpful.
Skin Rejuvenation Treatments
If you are concerned with visible signs of aging, a number of treatments are available. There are surgical treatments such as facelift and eyelid surgery however if you prefer a less invasive approach, there are effective non-surgical treatment solutions (such as Laser skin resurfacing, Skin rejuvenation, Medical Microdermabrasion, Skin Peels, Dermal fillers, Line & wrinkle smoothing treatment) to counter the aging process and to restore a firmer, toned, healthy looking skin, ironing out lines and wrinkles.