The skin is the largest organ in our body with a surface area of around 1.5 – 2m. The mass of the skin (cutis) is about 3-4 kg and its thickness is between 0.2 (lips) and 5mm (feet), depending on the body region.
The skin has multiple functions; it protects our body from environmental influences, regulates internal bodily processes and conveys many sensory impressions. The appearance of the skin not only depends on external factors or internal metabolic reactions, but can also be influenced to a considerable extent by the psyche. Emotions can find their outlet through skin reactions. The condition of our skin can affect our overall psychosocial picture, our impact and our self-esteem.
It has a layered structure with three functionally separate areas: the epidermis (upper skin) | the corium (dermis or leather skin) | the subcutis (subcutaneous fatty tissue). The hair, sebaceous, sweat and scent glands are embedded in the cutis (epidermis + dermis).
The epidermis forms the surface of our body and continuously grows from the inside towards the surface (14 days). On this way it gets keratinized and is finally shed at the top (14 days).
It consists of five layers, with the top layer being the cornea (stratum corneum). It consists of dead skin cells and is the top barrier against external influences and injuries. At the same time, it prevents the penetration of most cosmetic active ingredients.
The dermis is a connective tissue that is well supplied with blood and connects to the balsal membrane of the epidermis. It supplies the epidermis and removes metabolic products from it. In addition to hair, the dermis also contains sebaceous glands, which are responsible for lubricating the skin and hair in order to protect them from drying out.
The texture and quality of the skin are influenced by many internal and external factors (age, sun exposure,
climatic conditions, hormones, medication). The choice of cosmetics must be adapted to the current skin needs
and its rhythms:
during the day the skin’s immune defenses are strengthened, at night this barrier function weakens, the TEWL is increased and the inflammatory activity is increased.
the complexion of the skin fluctuates, especially in women, over the course of their menstrual cycle (UV sensitivity, dryness)
seasonal rhythms: the skin is subject to natural fluctuations over the year, which are amplified by exogenous, seasonal environmental changes. In spring to summer, the lipid peroxidation of the skin increases, favored by UV exposure. In winter, the pH value of the skin increases, the moisture and lipid level is reduced. As a result, the protective function is reduced and the skin reacts very sensitively to irritation. The dry, low-fat complexion is reinforced by the low-moisture heating air and the low outside temperatures.