The Human Body's Non Specific Defence.

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The Human Body's Non Specific Defence 

The skin 

The skin, in terms of surface area covered, is the largest organ of the body. It is the organ we see first (and indeed one of the few organs we can actually see when looking at a naked human body) and is of great importance in the defence of the body and thus in the delivery of nursing care. Further, since it reflects physiological and pathological changes in other areas of the body, skin changes can be used to aid both nursing and medical diagnosis.

Another name for the skin is the integument (Latin integrere to cover over, protect) -The Longman Dictionary of the English Language (1984) defines integument as 'skin, membrane or husk'. Another term sometimes used for the superficial skin is the cuticle; hence the use of the word cutaneous, meaning pertaining to the skin.

Just as the husk on a fruit or berry protects it from drying up in drought or swelling up in rain, so does the skin covering protect the body from the undue entry or loss of water. The skin contains glands known as sebaceous glands. These are associated with the hair follicles and are most numerous on the scalp, the face, the middle of the back and around the genitalia. They produce a substance known as sebum which comprises triglyceride, waxes, paraffins and cholesterol. The main function of the sebum is to waterproof the skin but it is also thought to have an anti-bacterial action. The skin also protects from all the minor mechanical blows that the environment deals for example pressure and friction When intact, the skin is virtually impermeable to micro-organisms, and also protects from chemicals (weak acids, alkalis etc.) and most gases - although same gases developed for use in chemical warfare can be absorbed through the skin. The integument gives some protection from physical trauma, for instance from some forms of particulate radiation such as alpha rays and, to a lesser extent, from beta rays. The skin is totally impermeable to alpha rays and beta rays can only penetrate a few millimetres thus protecting the underlying organs from their potentially harmful effects. In addition the skin is protected from the harmful effects of ultra-violet radiation by the production of melanin within it.

On each square centimetre of skin there may be up to 3 million micro-organisms, most of which are commensals. A harmless association exists between humans and their commensals (literally, ‘table companions', from the Latin), to the sole benefit of the latter. The bacteria commonly present as commensals on the skin include Corynebacterium, and Staphylococcus epidermis.

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The skin does not provide a very hospitable environment for bacteria unless they have become adapted through evolution to live there, and commensals have, in general, become adapted to live off human skin scales and the slightly acid secretions produced by the skin. The micro-organisms tend to live in the deeper layers of the stratum corneum near to their food source. Hence, they are not normally shed with desquamation. The application of strong deodorants, and the use of strong soaps that alter the skin pH from acid to alkaline upset the fine balance that exists between our parasites and us. ...

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