Most people do not really give their skin a second thought. Yet the skin that covers your body is a truly remarkable and complex material which performs many different functions. It is strong but flexible, waterproof but absorbent, elastic, washable, anti-bacterial, self-repairing – and designed to last a lifetime. So what is this amazing material?
Surface area: 1.5 – 2 sq m.
Weight: 4 kg – around 7 % of total body weight.
Thickness: 1.5 – 4.0 mm.
1 sq m of skin contains 70 cm of blood vessels, 55 cm of nerves, 100 sweat glands, 15 oil glands, 230 sensory receptors and 500,000 cells.
The average person sheds 18 kg of skin cells in a lifetime.
The skin contains 5 % of the body’s entire blood supply.
It is true to say that the skin is the most complex organ in the whole of the human body. It is also the largest organ and performs a host of important functions that are literally vital to life. Most of which are concerned with protecting the body and helping it to maintain its natural internal balance – a process known as homeostasis.
Here are some of the things the skin does.
The skin is equipped with a complex array of immune sentinels whose role is to constantly monitor for foreign molecules.
The skin repels unwelcome invaders such as bacteria, UV radiation and many other substances that could harm the body or upset its natural balance, and also protects the body against injury.
You may wonder how the body manages to maintain a more or less constant temperature while skiing in the snow or sunbathing on a beach. The answer lies again, largely, in the activity of the skin. Blood vessels in the skin regulate internal heat either by dilating or constricting to regulate your body’s temperature. When you blush or flush it is because the blood vessels close to the skin’s surface have dilated, so more blood is flowing through them, where they can be cooled down by the outside air. By contrast, on an icy day you may notice that your skin has become very pale. This is because the blood vessels in the skin have constricted to maintain heat inside your body.
What makes a mohair sweater itch? What makes you pull away your hand from a burning hot plate or a sharp knife? The answer lies in special nerve receptors found in the skin. These receptors are sensitive to different types of stimuli such as pressure, temperature, pain and irritation.
The skin also plays an important role in a various chemical processes that take place in the body, known as metabolic processes. One example is that the skin stimulates the production of vitamin D, often called the ‘sunshine vitamin’, by reacting to sunlight on the skin. Vitamin D is needed, among other things, to enable to our bodies to absorb the mineral calcium which is vital for healthy bones and teeth.
Another example is the production of melanin – a chemical that absorb UV light and protect us from sun damage.
In my next post I will talk about how the skin works in harmony with other body organs and tissues and what happens when this harmony becomes out of order.
We all want skin as smooth as a baby's, don't we...?