The skin is the largest organ in the body, comprising about 15% of the body weight. 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. The skin consists of three main layers: epidermis, dermis and subcaneous tissue.
Health, resilience and youthful appearance of the skin depend, among other things, on several key classes of biological molecules, the most important skin molecules are collagen, elastin, glycosoaminoglycans and proteoglycans.
Collagen is a protein forming the structural grid that holds other skin structures. It gives the skin its strength and durability. Increasing collagen production is important because age-related decline in the collagen synthesis is partly responsible for the signs of skin aging such as thinning, wrinkles and sagging.
Elastin is also a protein. It is more stretchable than collagen and helps maintain skin resilience and elasticity. When both elastin and collagen are abundant and undamaged, the skin easily regains its shape after being stretched or folded. Just as collagen, elastin deteriorates with age, leading to wrinkles and facial sag.
Glycosoaminoglycans (GAGs) and proteoglycans are special biological polymers whose key role is to hold moisture in the skin. In essence, they are extremely effective natural moisturizers – far more effective that common cosmetic moisturizers. Hydrated GAGs and proteoglycans help the skin stay plump and fresh and provide mechanical support for skin cells. In particular, N-acetyl-D-glucosamine, D-glucosamine hydrochloride, and D-glucosamine sulfate are often used as supplements to increase skin moisture.
Sebum is an oily secretion produced by sebacious glands, tiny ducts adjacent to hair follicles. Sebum is secreted into the follicle, from which it spreads over the hair and skin. The main role of sebum is to waterproof the skin and hair. Both excess and lack of sebum are undesirable. Excess sebum is associated with oily skin and acne. It is particularly common in adolescents as the increased levels of sex hormones stimulate sebum production. Lack of sebum, which is common in middle and older age, leads to skin dryness and accelerates wrinkle formation.
Sweat is a salty, watery solution produced by sweat glands, numerous microscopic channels opening onto the skin surface. As sebum and sweat mix up on the skin surface, they form a protective layer often referred to as the acid mantle. Acid mantle has a particular level of acidity characterized by pH from about 4 to 5.5. A pH of 7 is considered neutral, above 7 is alkaline, and below is acidic. In addition to helping protect skin from “the elements” (such as wind or pollutants); acid mantle also inhibits the growth of harmful bacteria and fungi. If acid mantle is disrupted or loses its acidity, the skin becomes more prone to damage and infection. The loss of acid mantle is one of the side-effects of washing the skin with soaps or detergents of moderate or high strength.
The skin does not exist in isolation from the rest of the body. Hence, skin rejuvenation has a much better chance of success as a part of a comprehensive anti-aging strategy.
Contrary to popular belief, aging is not a single process, but rather a group of processes that involve different mechanisms. The mechanisms of aging can be roughly divided in two groups: (1) accumulation of random damage at the cellular level a.k.a. micro accidents; and (2) genetic programs of aging a.k.a. aging clocks.
Potentially harmful molecular accidents occur in our cells all the time. The vast majority, however, cause no harm because the damage is quickly fixed by reparation enzymes. Unfortunately, a small percentage of lesions is missed by the repair systems and remains for good. As unrepaired lesions accumulate, they begin to interfere with vital cellular functions. With age, the accumulation of unrepaired damage accelerates, partly because repair mechanisms themselves get damaged and lose efficiency.
Aging and Stress
Stress has a very close relationship to the development of age-related diseases and to the aging process itself. Stress or, more accurately, stress response is essentially a complex adaptive reaction of the body. Stress response is vital for survival, especially during emergencies, such as injury, infection or immediate danger. Stress response was especially important in the early days of mankind when life was tough, and danger, infections and struggle were a part of the daily routine.
Among other things, stress involves quick mobilization of energy reserves, increased supply of fuel and stimulation of the brain, muscles, heart and other organs essential for immediate survival. In essence, stress response is a biological overdrive mode which helps escape from a tight spot, but at a high cost of wearing down the body.
Read more about stress and emotions effects to our life