Structure and Function of your Skin
Your Skin consists of three layers - the epidermis, the dermis, and the subcutaneous tissue. The surface epidermis is a relatively thin layer. Beneath the epidermis is the thicker and the much stronger dermis. The subcutaneous tissue or the fat containing layer lies below the dermis.
The epidermis is a fairly thin layer. Its thickness varies around the body, depending on the special needs of that area. For instance, the epidermis over the eyelids is particularly thin, while that over the palms and soles is very thick.
The epidermis is itself made up of several layers. On the surface is the horny layer - the stratum corneum. This layer is made up of dead cells, which are continuously being shed. The cells are shed off as small aggregates which are normally too small to be seen; sometimes, however, these aggregates become larger and are then visible as scales. This is exactly what happens in dandruff and when our skin is deprived of moisture.
Below the layer of dead cells are stacks of living cells comprising the stratum malpighi. This layer produces the main skin protein known as epidermis. The innermost layer of the epidermis or the basal layer is where new cells are produced. These new cells take about a month to travel to the surface. In some diseases, however, the movement of the cells to the surface is speeded up and this also results in scaling.
The skin pigment, melanin, is produced by special cells called melanocytes. Melanin is very important for the protection of the skin from the sun; this is precisely the reason why melanocytes are stimulated on exposure to the sun, resulting in darkening of the skin.
The dermis is a much thicker layer than the epidermis. It is made up of a connective tissue framework in which are embedded blood vessels, lymph vessels, nerves, several types of glands, hair and a whole variety of cells. The connective tissue of the dermis is made up predominantly of a protein called collagen. Presently, this protein is being popularly used for the treatment of a variety of skin problems like wrinkles and scars. For information about skin disorders go to our skin disorders section. Elastin or elastic fibres are the other type of protein fibres in the dermis.
The dermis also contains a complex system of bleed and lymph vessels and a highly complicated nervous system. The nerves receive and pass on an endless stream of valuable information to the body. Any type of skin massage is thought to facilitate the drainage of lymph glands and also to enhance the circulation of blood. Similarly; it has been suggested that massages soothe the nerves in the skin.
The Subcutaneous Tissue
Below the dermis is the fat storage bank of the skin. The amount of the fat stored varies in different parts of the body. In some parts of the body it has been given fancy names like' cellulite'. This tissue has been a source of considerable controversy in scientific and cosmetic circles.
The skin Glands
The dermis has three types of glands: the apocrine glands, the eccrine glands, and the sebaceous glands.
The apocrine glands are present in association with the hair follicles. They are found mainly in areas where there is obvious body hair such as in the armpits and around the area. These glands are under hormonal control. A large part of the body odour can be traced to the apocrine glands. By themselves, the secretions of these glands are odorless, but bacteria(which are normally present on the skin) act on the secretions to produce the characteristic odour.
Eccrine Sweat Glands
The eccrine sweat glands are distributed widely over the skin and produce a much larger amount of secretions. These glands are concerned with the regulation of body temperature. Under normal circumstances, the sweat glands produce about half a litre of sweat in a day. In very hot climates, the generation of sweat increased tremendously and as the water is lost, the body cools down.
The dermis also contains sebaceous glands. These are present throughout the entire surface of the skin, except on the palms and soles. They are particularly numerous in the scalp and on face. These glands open into the hair follicles and secrete an oily lubricant - the sebum. This contains cholesterol, proteins, fatty acids and waxes. Sebum forms a thin film which lubricates the skin; it also forms a coating on the hair, keeping them soft and shiny. When sebaceous secretions are inadequate, the epidermis comes dry and wrinkled and when the glands secrete heavily, the skin becomes oily and shiny.
Functions of the Skin
The functions of the skin are truly a paradox - skin is both a barrier surrounding and protecting your body innumerable external assaults and at the same time, it is the means of your constant contact with the environment. One of its main jobs is to regulate temperature. Another is to prevent germs and poisons from invading the body. Just as important is its task of preventing the loss of body fluids, as it forms an almost waterproof barrier. Simultaneously, it also functions as an active organ of excretion, helping to rid the body of wastes in the form of sweat.
On a psychological level, your skin is the most active link with your surroundings. Quite apart from its role in your personal appearance, the skin is vital in conveying the sense of touch and forms the principal organ of sexual attraction and communication.
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