The skin is our largest organ. It covers almost the entire body, has a total area of around two square metres (22 square feet) and accounts for about 15 per cent of our body weight.
It works not only as a shield – protecting our insides from the outside – but also regulates body temperature and eliminates toxins and waste materials through perspiration.
What else do we know about this phenomenal organ? Let’s flesh it out.
natural deodorants put to the test
The skin has three layers. The top layer is the waterproof epidermis; the middle layer is the dermis, comprised of connective tissue, hair follicles and sweat glands; and the bottom subcutis layer is made up of fat and large blood vessels. This bottom layer is attached to muscles.
Our skin is made up of about 300 million skin cells. Melanocyte cells in the epidermis produce a pigmented protein called melanin which determines a person’s skin colour. Every person has the same quantity of melanocytes, but it is the cells’ activity which affects the colour of one’s skin – and eyes.
There are two types of melanin: pheomelanin causes a yellow to red colour in skin, and eumelanin causes a dark brown to black colour. Skin colour is not, however, set from the day we are born; it can take up to six months to develop our permanent skin tone. Albinism – an absence of pigment in the skin, hair and eyes – is caused by a lack of melanocytes and affects one in 110,000 people.
Lighter skin tones only started to come into existence around 20,000 to 50,000 years ago when humans moved towards colder climates. Their skin evolved to become lighter, thus making it easier to produce vitamin D.
The skin plays more practical roles than determining our colour. It is through the skin that we understand the world around us through feel and touch. Numerous nerve endings in the skin allow us to sense pain, temperature and pressure. In fact, the skin has at least five different sense receptors.
In the skin’s dermis layer, we have on average between two million and five million sweat glands. They help to regulate body temperature – when hot, the glands release water and fatty liquids to cool the skin.
The fitter you are, the faster you begin to sweat while exercising. That is because the body is quicker at recognising that you need to cool down to be able to exercise for longer. Athletes can sweat off as much as 2 per cent to 6 per cent of their body weight when performing intense exercise in hot conditions. Men also tend to sweat more than women, even though women have more sweat glands than men.
There are two types of sweat: sweat made of water, salt and potassium and whose purpose is to cool the body down, and sweat comprised of fatty acids and proteins that is made by a different gland when under stress. This “stress sweat” tends to smell worse as it does not evaporate as quickly as regular sweat and combines with bacteria on the skin. Sweat itself has no odour.
While skin covers most of our body – weighing around four kilograms (nine pounds) in the average adult – its characteristics vary according to where on the body it lies. Skin covering the knuckles is more stretchy and stronger than that which covers the belly, for example. The thickest skin we have is on the soles of our feet at 1.4mm; the thinnest is on our eyelids at 0.02mm.
Just like a snake, we “shed” our skin. Every 28 to 30 days it is completely renewed as new cells are produced in the subcutis layer and rise to the surface. This means we are constantly shedding skin cells – 30,000 cells a minute, in fact. It is estimated that about 50 per cent of the dust found in homes is actually your dead skin cells.
If this is the case, how is it possible that tattoos are permanent? Tattoos work because the tattoo needle inflames the dermis layer of the skin and white blood cells called macrophages respond to heal the wound. They do this by “eating” the dye and when they die, the colour is passed on to newborn macrophages. Laser tattoo removal kills off the macrophages that contain this dye.
The skin is vital for our protection – and we must take care to protect it. One of the best ways to do this is to avoid too much sun. One of the main causes of skin ageing is ultraviolet rays from the sun or tanning beds. These can also cause skin cancer.
Ways to protect yourself from the sun include wearing a hat, protective clothing and sunglasses as well as sunscreen with a sun protection factor (SPF) of at least 15. Bear in mind that you need to cover your sensitive, and often forgotten, neck and neckline as well as your face.
The sun is strongest between 10am and 4pm (depending on where you are in the world) so take care to avoid it during these times. There is evidence to suggest that wearing sunscreen every day, regardless of the weather, can slow the skin’s ageing and, of course, reduces the risk of skin cancer.
By looking after my skin I’m not only preventing another melanoma growth, but will also have younger-looking skin than all my friends by the time I’m 50
Heather Barlow, a university student in Hong Kong, spent her childhood in the hot tropics. Even though she has red hair and sensitive skin, she stubbornly resisted wearing sunscreen.
However, after having a melanoma mole removed from her back at the age of 16, she is now extremely careful about her skincare. While her friends might spend their summers working on getting a deep tan, Barlow resigns herself to the shade, wearing a hat and SPF 50 sunscreen.
“I used to want to get a tan and hated being so pale and freckly,” Barlow recalls. “But now I know that by looking after my skin I’m not only preventing another melanoma growth, but will also have younger-looking skin than all my friends by the time I’m 50.”
Hong Kong based dermatologist Dr Bessie Tong Bik-sai describes how some skins are naturally more sensitive than others. She says that “sensitive skin is a condition characterised by exaggerated reactions to personal conditions, environmental factors and, sometimes, skincare products”.
One classification system splits sensitive skin into four types: type 1, prone to develop blackheads, whiteheads and pimples; type 2, prone to facial redness and flushing because of heat, spicy food and emotion; type 3, dry, flaky, itchy, stinging and giving a burning sensation; and type 4, having an impaired skin barrier and being susceptible to developing contact dermatitis due to different allergens and irritants.
There are many other skin problems and disorders. Hong Kong aesthetician Gillian Elsworth lists the most common ones in her clients as acne, eczema, dermatitis, psoriasis, various pigmentation issues, dryness and dehydration.
Acne is a skin disorder that plagues many teenagers across the globe caused by an overproduction of cells that line the sweat glands. Four out of five teenagers will experience some form of acne, while it is five times more common in adult women than adult men.
Our skin is vital to our health and, throughout the ages, humans have come up with many different – and bizarre – ways to look after and alter their skin.
In ancient Europe, chalk powder and crocodile dung were used to lighten skin tones as lighter skin was considered a sign of wealth. Today, a facial lotion made of the user’s own blood has been created. Bird poo, caviar, gold and even the stem cells from newborn baby boys’ foreskins (after circumcision, thank goodness) have all been used in some form of skin cream or facial.
Luckily, skin experts generally offer much simpler – not to mention cheaper – techniques to keep your skin happy and glowing. Elsworth says that the best things you can do for your skin are to get lots of sleep, drink lots of water and stay hydrated, and minimise sun exposure.
She describes wrinkles as a perfectly natural evolution of our skin resulting from expression and natural ageing factors. However, certain factors can exacerbate wrinkles, such as too much sun or air conditioning, genetic
predisposition, smoking, and alcohol.
There is evidence that smoking can cause premature ageing of the skin as it may reduce the production of collagen, which is a protein that supports skin strength and elasticity.
Alcohol also has negative effects on the skin by dehydrating us and making our skin look older and more tired.
Elsworth says using good quality skincare products can also help – ones containing vitamin A, for example, can be beneficial. She suggests looking for products with quality ingredients and getting advice from a professional if you have any specific problems or concerns.
Tong reinforces that avoiding the sun and using sunscreen which provides coverage for both UVA and UVB rays are key elements in preventing skin ageing. She also suggests eating foods high in antioxidants, such as lemons, cranberries, blueberries, blackberries, beans, artichokes, pecans, walnuts and hazelnuts.