Epidermis consists of several layers. The layer facing the environment forms our skin barrier.
It is especially this layer that at the same time is the thinnest of the skin, which protects against external influences. This layer consists of dead horn cells and fats that are constantly repelled from the skin’s surface and therefore must be constantly renewed. It mourns the inner layer of the epidermis.
This layer is thicker and consists of several layers of live horn cells that are constantly dividing and moving upward. During this upward movement, the horn cells become flat, lose their nuclei and eventually become dead horn cells. It takes approx. four weeks for a cell to move up to the top. The live horn cells produce fats, also called lipids, that are transported out of the cell and form a kind of kit or glue that bonds the dead horn cells together.
Dead corpuscles are approached towards the skin’s surface by a protein called keratin. Keratin is a hard, firm and highly resistant fabric. The fats consist of ceramides, cholesterol and free fatty acids and are called physiological fats, as they are naturally formed in the body.
The epidermis contains no blood vessels, but receives all its blood supply and thus supplies oxygen and nutrients from blood vessels in the skin.
Skin barrier and skin color
The living cells of the epidermis produce a variety of fats that settle between the horn cells and form an almost completely waterproof barrier. The skin barrier partly prevents foreign microorganisms from freely invading the body and partly prevents the water from evaporating from the deeper layers of the skin and thus drying out the skin and dehydrating.
The epidermis layer also contains pigment cells (melanocytes). They produce the dye melanin, which protects the underlying leather skin from the harmful UV rays of the sun. It is melanin that gives the skin the brown color after staying in the sun.
Cell turnover in the epidermis
The dead horn cells of the epidermis eventually wear off due to the friction the skin is exposed to. In this way, the epidermis keeps a fairly constant thickness (below one millimeter). The wear occurs especially when we work and work with our hands, but also as a result of all movements and wear from the clothes. A large part of ordinary house dust is actually made up of these dead cells!
It takes an average of two months before a newly formed skin cell reaches the skin surface and wears off. The body parts that are subjected to greater wear have a thicker epidermis, and therefore the turnover of cells in the skin of these body parts takes longer.
From new skin cell to dandruff
The walk from a new skin cell to the horn-layer takes normal approx. 4 – 6 weeks, when the skin cells are hit by dandruff. New skin cells are constantly being formed – so new ones are coming.