Skin

The skin is a Organe composed of several layers of fabric S. It plays, inter alia, the role of protective envelope of the body.

At the man, it is one of the most important bodies of the body compared to its surface and its mass: at the adult, approximately 2 m ² for 5 kg.

The Dermatologie is the medical speciality which treats affections of the skin.

Histology

On the anatomical level, the skin includes/understands two principal parts. The mean surface part is called the skin, attached to a part interns thicker: the Derm. A third layer, deeper, constitutes the hypoderme but is classically not comparable with a layer of peau.
The skin unit and its Phanère S (Nail S, Hair S) name the tegument.

Physiology

Maintenance of the body temperature

The secretion of Sweat assistance to control the body temperature. It increases with the temperature, and causes a cooling thanks to its evaporation on the surface. It decreases when the temperature affaiblit.
The Mammifère S often have a skin covered with hairs being used mainly to isolate the body from the cold, and this by creating a layer of hot air between the skin and the hairs.

Protection

  1. the skin constitutes a physical barrier which protects fabrics and subjacent bodies from the external aggressions: it is an effective barrier vis-a-vis the Microorganisme S.
  2. It avoids the losses of body fluids, represents a semipermeable membrane vis-a-vis the external liquids.
  3. It is a protection against the ray S of the sun, in particular thanks to its Pigmentation.

    See also: Color of the skin

Perception

The nervous terminations contained in the skin, and in particular at the end of the fingers, make it possible the man to explore his environment by the Toucher. The skin thus allows a sensitivity to the Pression, the Chaleur, and the Douleur. It has four types of receivers, which react according to different Stimuli, and which turns over interpretable information by the brain. This information traverses the spinal column, to thalamus via two types of channels: one for information concerning the pain and the temperature, the other for the touch with properly spoken (texture, hardness, etc…).

The nociception is treated in the medical encyclopedia Vulgaris

Immunity

Certain épidermiques cells play a big role in the immunizing protection of the human body. One finds there dendritic cells, otherwise called cells of Langerhans.

Blood tank

The derm contains a network of Blood-vessels accounting for approximately 10% of blood in the adult. During the physical exercise, the blood-vessels of the skin contract to support the blood contribution with the Muscle S.

Synthesis of the vitamin D

During the exposure to the rays Ultraviolet S, the skin takes part in the synthesis of the Vitamine D necessary to calcic balance of the human body.

Leather

One calls Cuir the thick skin of certain animals, like the buffalo.
Le leather is also the tanned skin of certain animals (Bœuf, Chèvre, Chevreau, lamb…).

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