The skin is one of the body’s organs. It is the largest organ in the body, with a mass equal to about 15% of that of the entire body.
The total surface of skin in an adult ranges from around 12 to 20 ft². Its composition is about 70% water, 25% protein and 2% lipids. The other lesser components include trace minerals, nucleic acids, glycosoaminoglycans, proteoglycans and several other chemicals.
The skin is composed of three primary layers: the Epidermis, Dermis and Hypodermis or subcutaneous layer. The composition and function of each layer is described below.
- The outer layer of the skin
- Thickness is typically 0.1mm-1mm
- Avascular (possessing no blood vessels)
- Divided into five sublayers, known as strata: the corneum, lucidum, granulosum, spinosum, and germinativum (basale)
- Contains four distinct layers of cells:
- Keratinocytes – These are the most abundant cells and produce the keratin protein which provides protection, in addition to producing enzymes and antibiotics that detoxify chemicals might otherwise damage the skin.
- Melanocytes – These cells produce melanin which gives skin and hair their colour.
- Merkel Cells – These cells help transmit sensory messages.
- Langerhan Cells – Essentially a part of the body’s immune system located in the skin, which prevent unwanted foreign, potentially harmful, substances from entering.
- Each day dead skin cells are shed by the epidermis in a process called Keratinization, or skin renewal, which overall takes approximately one month. Bus as people age, this process decelerates and takes longer to complete. When the Keratinization begins to slow, the skin starts retaining a greater number of dead cells, resulting in a dull and lifeless appearance.
- The condition of the epidermis determines how “fresh” a person’s skin appears and also how well it absorbs and retains moisture.
- Situated immediately below the epidermis
- It comprises the greatest portion of the skin
- The dermis is composed of two layers:
- Papillary Dermis
– This is situated directly below the epidermis and contains fibroblast cells which play a critical role in the healing of wounds. These form collagen, a component of connective tissue responsible for structural support of the skin.
– The proper functioning of fibroblast cells is very important in determining the overall health of the skin.
- Reticular Dermis
– This is situated beneath the layer of papillary dermis and is responsible for producing collagen and elastin (a protein found in connective tissues that is elastic and iresponsible for the skin’s resilience).
- Papillary Dermis
- The dermis contains blood and lymph vessels, nerves, sweat glands, sebaceous glands and hair roots.
- The dermis provides tensile strength, support and protection to the underlying muscles, organs and bones.
- The dermis provides the structural integrity, elasticity and resilience of the skin.
- Wrinkles have their physical origin in the dermis. For this reason, any anti-wrinkle treatment will only succeed if it can reach deeply into the dermis.
The Hypodermis / Subcutaneous Layer
- The hypodermis is the innermost layer comprising the skin.
- The hypodermis is composed of fat, blood vessels and connective tissue.
- Sweat glands and very small muscles that are attached to hair follicles are located in the hypodermis.
- The hypodermis is anchored to to deep tissue.
- Regulation of the temperature of the body and skin is based in the hypodermis.
- The hypodermis stores energy in the form of fat.
- The loss of subcutaneous tissue (i.e. Tissue from the hypodermis), which often comes about with aging, leads to sagging of the face and accentuates wrinkles.
- The skin facilitates perception of the surrounding environment – effects such as pressure, touch, temperature and pain.
- The skin provides a barrier to protect the body against friction, pressure, heat and cold, chemicals, radiation, bacteria and other micro-organisms;
- The skin also plays a role in the body’s fluid balance and temperature regulation. It also facilitates the synthesis of Vitamin D.
There are two recognised types of aging, known as intrinsic and extrinsic.
Intrinsic aging is the process of natural aging. It is a continuous process, typically beginning in a person’s mid-20s, although its effects are usually invisible for decades.
In intrinsic aging of the skin:
- There is a slow-down in the production of Collagen, and elastin, which gives the skin its elastic quality, reduces in its effect of helping the skin to spring back into shape.
- Dead skin cells do not depart so quickly and the re-generation of skin cells decreases somewhat.
The signs of intrinsic aging are:
- Thin, transparent skin.
- Fine lines and wrinkles.
- Loss of fat from beneath the skin, leading to hollowed cheeks and eye sockets as well as a noticeable loss of firmness in the hands and neck.
- Bones detaching from the skin due to bone loss. This causes the skin to sag.
- Dryness of the skin, sometimes accompanied by itching.
- An inability to sweat adequately, resulting in inadequate skin cooling in warm environments.
- Hair turning grey, and eventually white.
- Loss of hair from the scalp.
- Unwanted hair.
In extrinsic aging, external factors, includin those due to the environment, regularly act together with the normal aging process to prematurely age our skin. Most premature aging is caused by over exposure to the sun. Other external factors that prematurely age the skin are repeated facial expressions, sleeping positions, smoking and the effects of gravity.
Causes of Extrinsic Aging
Sun Exposure – If the skin has inadequate protection from the sun’s rays, even just a few minutes of daily exposure to excessive sunlight over the years can cause noticeable changes in the skin. Freckles, age spots, facial spider veins, rough leathery skin texture, fine wrinkles, loose skin, a blotchy complexion, actinic keratoses (thick, rough, reddish wart-like patches of skin), and skin cancer can all be traced to excessive exposure to the sun.
Elastin is also attacked by the sun. And skin weakened by the sun ceases to spring back much earlier than skin protected from the sun’s ultra-violet radiation. Skin also becomes loose, wrinkled and leathery significantly sooner when exposed frequently to sunlight without protection.
Those inhabiting sun-intense areas of the world can even show signs of photo-aging in their twenties. Whilst photo-aging symptoms might seem to appear almost overnight, in reality they lie invisible beneath the surface of the skin for many years before manifesting themselves.
Facial Expressions – Repeated movement of the muscles of the face create fine lines and wrinkles. Each time a facial muscle is employed, a groove is formed beneath the surface of the skin. This is why we see lines form related to each facial expression. As the skin ages and loses its elasticity, it stops springing back to its initial state without lines.
Sleeping – If a person rests their face on the pillow in the same way each night for several years, this activity will also result in wrinkles, sometimes known as sleep lines. Such wrinkles will eventually become etched onto the surface of the skin, no longer disappearing when the head is not resting on the pillow. This cause of wrinkles is avoided by those who sleep on their backs.
Gravity – Gravity is a constant factor that pulls down on our body from the time we are born. Changes in the skin resultant from gravitational effects become more pronounced as people get older. The effects of gravity regularly become evident for those in their fifties, when the skin’s elasticity significantly declines.
Smoking – Smoking causes biochemical changes in people’s bodies that accelerate the aging process. Statistical research indicates that a person who smokes 10 or more cigarettes a day for a at least 10 years is more likely to develop deeply wrinkled, leathery skin than a non-smoker.
While the intrinsic aging process cannot be stopped, signs of premature aging (extrinsic aging) can be significantly reduced by protecting the skin from the sun, stopping smoking and reducing repeated facial expressions. A reduction in stress, taking frequent exercise and maintaining a healthy diet also help.
Rejuvenating Skin Treatments
For those concerned with reducing the visible signs of aging, a number of treatments are available. There are surgical treatments such as Face Lift and Eyelid surgery (blepharoplasty). But for a much less invasive approach, there are some highly effective non-surgical treatments – such as PRP Skin Rejuvenation, Chemical Peel, Facial Fat Grafting, Dermal fillers, and Botox – all of which help to counter the aging process and to restore a firmer, more toned and healthy looking skin, with a reduction in lines and wrinkles.