Skin: more than one simple barrier

Skin: more than one simple barrier
More than one simple envelope, the skin is a body with whole share. It is even that whose mass and surface are most important. True interfaces with the outside world, it protects the other bodies from the infections, the wounds and the harmful solar rays. Endowed with an extreme sensitivity, it allows the direction of the touch.

The skin consists of three superimposed compartments: skin, the derm and the hypoderme.

Skin
The skin is made up of two fabrics: an external layer called skin and an internal layer called derm or corium. The surface of the skin, the skin, is made up of died cells, which are eliminated when the subject moves, when it puts clothing or when it is washed. This layer of dead cells is often called it “distorts skin”. The skin consists of four layers: the basal layer, the layer of Malpighi, the granulous layer and the cornea layer.

Cut skin 

The derm
Just in lower part, of the skin the derm is located, in which at each second the cells multiply to replace those which are eliminated.

The derm (or corium) is the thick fabric, relatively flexible, which constitutes the internal layer of the skin. It allows the protection and the repair of damaged fabrics and is four times thicker than the skin (the external layer of the skin). The derm is primarily consisted of protein called collagen, which works out cicatricial tissue to repair the cuts and the abrasions. The derm nourishes the skin and contains the nervous terminations and the blood-vessels, and sometimes of fat fabric. The base of the hairs is also located in the derm. Under the derm the hypoderme is, which is a subcutaneous fat layer.

The hypoderme
Located under the derm, the hypoderme is a fabric rich in grease and blood-vessels. Its principal role is to deaden the pressures to which the skin is subjected. It also protects the organization from the temperature variations. It is particularly important in the zones having to support an impact such as the buttocks or the heels. On the other hand in other zones, it is quasi-non-existent.

Skin reconstituted except for the hair!
A Parisian team of the INSERM directed by Yann Barrandon has just proven that the skin of an adult mammal contains original cells able to reconstitute the essence of the skin, including sébacées glands and the hairs. These original cells are located in the pilous follicules. This discovery published in the Cell review opens important prospects in dermatology, to support the processes of cicatrization or to improve the results of Clerc's Offices of skin at the badly burned persons, but also in cancerology, to include/understand the origin of certain cancers of the skin. In beauty care, the applications could relate to the treatment of the fall of the hair or excesses of pilosity. 

David Bême, on February 2nd, 2001

Source: Concealment, January 2001, vol. 104,233-245.

Utility of the care

The skin also plays a big role in the temperature control of the body. Even if the cutaneous fabric of an adult of average stoutness can weigh up to ten kilos, it has only the thickness of a sheet of paper by places, so that it can break easily and allow harmful bacteria, viruses or other micro-organisms to penetrate in the organization. The care of the skin is thus paramount. A thorough cleaning is essential. The baths are, in this respect, very useful and have several functions. 

The skin continuously secretes sebum and sweat, which have a protective role. The sebum is a natural greasy substance which prevents the drying of the skin. The sweat, which is slightly acid, has a preventive action on the bacterial proliferation. However, an accumulation of sebum, sweat and épidermiques cells dead can be harmful for health. In the event of excess of perspiration, sweat interacts with the bacteria on the surface of the skin and generates odors, phenomenon considered as unpleasant in certain cultures. The accumulation of sebum on the skin causes sometimes an irritation and stimulates the bacterial proliferation. However, the presence of bacteria of big number can constitute a problem in the event of cut or of scratch.

Lastly, the dead épidermiques cells also transport bacteria. The regular baths thus contribute to eliminate these died cells, sweat and the sebum. They also have virtues refreshing and alleviating, and stimulate circulation. The warm water causes a dilation of the surface vessels, which increases the blood flow and brings more oxygen and nutrients to cutaneous fabric. The frictions have the same effect and stimulate the venous return. Attention, the excess of baths can however cause a drying of the skin.