It envelops us and protects us like a cocoon, forming a barrier between the outside world and the inside of our body . A real impassable wall when it is healthy and the first line of defense against bacteria and viruses . But the role of the most visible and largest organ of the body would be very sad if it were limited to an antibacterial and antiviral action. Its usefulness goes well beyond ensuring good health and well-being . But what is this element which is part of us, ultra- sensitive and which feels the gentlest contact like pain ? We are obviously talking about the immense and incredible skin tissue that covers you from head to toe: your skin .
Function #1: Protection against dehydration
It is thanks to the outermost layer of the epidermis, the one that we can see and touch , that we are protected from dehydration . The stratum corneum or stratum corneum is indeed very interesting due to its hydro-retentive power . The hydrolipidic film which covers it is also not without interest.
EPIDERMAL LIPIDS : The cells of the stratum corneum are dead, flattened cells linked together by epidermal lipids . This helps “close the skin” and prevent “leaks” of fluids. The action is further reinforced by the hydrophobic nature of the lipids . As they "don't like" water, it cannot pass through them. A lipid deficiency separates the cells from the stratum corneum , leaving it porous like a sieve. Undernourished skin (lack of lipids ) then loses water ( dehydration ). Its texture becomes rough and more susceptible to chapping .
CONTENT IN NATURAL HYDRATION FACTORS (NMF: Natural Moisturizing factors) : The epidermis is covered with a water + lipid (fat) emulsion called hydrolipidic film renewed by the secretion of the sebaceous and sweat glands. The aqueous part contains natural hydration factors. These are substances on which water attaches. Among them, we find lactic acid , pyrrolidone carboxylic acid , urea , amino acids from perspiration and sebaceous free fatty acids . They are formed during cellular differentiation by keratinization of keratinocytes in the epidermis. Their hydro-retaining power helps preserve the elasticity , firmness and suppleness of the skin . When the quantity of NMFs decreases and the humidity of the stratum corneum drops below 8-10%, the skin becomes dehydrated , dry and rough .
Function #2: Protection against radiation
The basal layer or stratum basale is the deepest layer of the epidermis . Although it may seem counterintuitive, it is what protects us against UV radiation which may be the cause of hyperpigmentation .
MELANIN : When the skin is exposed to UV rays , it defends itself. Melanocytes ( basal layer cells ) produce melanin , the pigment that colors the skin to make it “ tan ”. But well beyond this aesthetic effect, this molecule actually serves to absorb radiation to protect the skin .
Function n°3: Protection against temperature variations
The fat cells of the hypodermis protect us from temperature variations.
ENERGY STORAGE : These fat cells are fat cells, filled with fats which they store so that they can later be used and transformed into energy . To store them, they must not escape and therefore these cells must be insulating . These adipocytes therefore store energy and insulate the body from cold and heat .
Function n°4: Protection against pressure, shocks and scratches
The first layer involved is the superficial layer of the skin : the stratum corneum coupled to the hydrolipidic film which protects it. The duo will allow good repair of scratches , good cell renewal and protection against repeated friction .
ACIDITY : The aqueous mantle which constitutes the hydrolipidic film on the surface of the epidermis is slightly acidic and creates an ideal environment for the enzymes involved in desquamation ( cellular renewal ) and for the repair of the stratum corneum when it is damaged.
THICKENING : Repetitive friction causes the skin to thicken in the contact areas (palms of the hands, soles of the feet).
The dermis plays more of a shock absorber role in combination with its undeniable involvement in healing processes .
STRUCTURAL COMPOSITION : The dermis can be considered as the mattress of the skin . Collagen , elastin , connective tissues and hyaluronic acid embedded in its gel texture give it firmness , elasticity and thickness which allow it to absorb shocks.
HEALING CELLS : Connective tissues contribute to the healing process thanks to fibroblasts (poorly differentiated cells) and mast cells (immune cells).
Finally, the hypodermis helps the dermis when it comes to absorbing shocks.
STRUCTURAL COMPOSITION : The fat cells held by a spongy and loose tissue (special collagen fibers) serve as a cushion and also absorb shocks . This helps protect the muscle layer : muscle tissue and fascia (fibrous tissues that surround the muscles ).
Function n°5: Protection against bacteria/viruses/fungi/chemical substances/Residues
A veritable impassable wall for the external environment, the stratum corneum and its hydrolipidic film play a key role in protection against pests ( bacteria , viruses , fungi , chemical substances, residues ).
EPIDERMAL LIPIDS : Epidermal lipids are a cement that “blocks” the interstices between the cornea cells . The result is a real “wall” of cells , impassable for pests .
ACIDITY : The protective acidic aqueous mantle which makes up the hydrolipidic film on the surface of the epidermis has a pH of 5.4-5.9 . The acidity of the skin then becomes conducive to the development of good microorganisms for the skin ( cutaneous flora ). These “ friendly bacteria ” will hunt and destroy “ enemy bacteria ” and other harmful things. This slight acidity also gives the skin a buffer against harmful alkaline chemicals.
The dermis contains sebaceous and sweat glands which also play a role in protection against external aggressions and contamination .
SWEAT & SEBACEOUS GLANDS : The sweat glands allow residues and toxins to be evacuated through perspiration . The production of sweat by the latter coupled with the production of sebum by the sebaceous glands contribute to the formation of the skin's protective hydrolipidic film .
Function n°6: Temperature regulation
It is at the dermis level that your body sets up thermoregulation mechanisms to keep your body temperature at 37°C , whatever the weather.
SWEATING : The sweat glands contained in the dermis activate when the body temperature exceeds 37°C . This releases heat and moistens and cools the surface of the skin , making it easier to lower body temperature .
Shiver : The hairs - whose roots are anchored in the dermis - stand up when the body temperature drops below average. This phenomenon, better known as “ goosebumps ” or shivering , helps maintain a thin layer of warmer air close to the skin . In addition, it works the “ muscle ” of the hair and therefore releases energy in the form of heat . The body temperature then rises.
VASODILATION OR VASOCONSTRICTION : Depending on the temperature , the blood vessels contained in the dermis will dilate to quickly evacuate heat or, on the contrary, contract to retain it longer within them.
Function No. 7: Control of sensations
Ah definitely, we haven't finished hearing about the dermis which gives your skin sensitivity, the sense of touch.
NERVE ENDINGS : The nerve endings present in the dermis are responsible for the sense of touch : pressure , vibrations , pain , heat , etc. The skin smells everything.
Function #8: Energy source
This fatty layer that is the hypodermis is not only there to annoy you when you feel concerned about weight gain . It is above all an energy storage zone.
ADIPE CELLS : The adipose cells of the hypodermis are in fact storage units , a “can” where the body stores fats ( lipids ) from nutrition . When it needs energy , the body connects its blood vessels to this lipid reserve and recovers the fatty molecules to transport them to the mitochondria where they will be transformed into energy .
The skin plays a role in our overall health, in our well-being but also physiological. It is the most visible indicator of our state of health. For example, a pale complexion may reflect a health problem and it may be that this health problem is linked to unhealthy skin that has allowed bacteria to pass through. Healthy skin and good health are therefore closely linked, both the cause and the consequence. It is therefore necessary to take care of both and food supplements can be the solution.