It's this time of year again when we go crazy when we see that big golden ball shining in the sky, albeit in my part of the world anyway and being of Celtic origin (I'm lucky not to have typical Celtic colouring) my kinsfolk like to take full advantage of lying in the sun. However the skin in the upper northern hemisphere has evolved such that does not have the same protection as those of who have evolved of living in sunnier climates. As a result it's not unusual here to see copious cases of sunburn. Some sun is beneficial to us and to understand what advantages and disadvantages the sun has you need to know how the largest organ in the body works.
HOW THE SKIN WORKS
The basics so you will understand how the skin works. The skin is comprised of 3 layers, the Epidermis the layer you can see, the Dermis the true skin and the subcutaneous. Cosmetics only work on the Epidermis and you can see how deep it is, if you have ever experienced a blister. A blister is caused when friction causes the Epidermis and the Dermis to separate and the fluid within the blister is lymph. The Epidermis has no nerve endings or blood supply that is why removing the top layer of a blister is not painful, not to be recommended though as it exposes the Dermis which is rich in nerves and a blood supply to infection.
The skin has several functions to secrete sebum that oily substance on your skin, this is to help keep the skin moisturised by trapping moisture and forming a barrier together with sweat known as the 'Acid Mantle' The Acid Mantle is slightly acidic and acts as a Bacteriastat to inhibit bacteria. The skin secretes sebum via the sebaceous glands within the hair follicles and sweat via theEndocrine glands (there are another type of sweat glands know as Apocrineglands these are found in the axillary and pubic regions unlike Endocrine sweat bacteria act on Apocrine sweat quickly and this causes the characteristic Body Odour, these glands only become active after puberty and have a role to play inpheromones)
Our body temperature is regulated by the skin this is due to the peripheral circulation either dilating to bring blood to the extremities of the body like the skin causing flushing to help loose some of the heat and also by sweating for as the sweat evaporates heat rises with it. The opposite happens when its cold the body conserves heat to vital organs more important than the skin, giving a more white/bluish appearance and may even induce shivering. At the base of everyhair follicle there is a tiny cilary muscle when its cold and we start to shiver this muscle contracts causing the hair to stand up trapping a layer of air next to the skin, giving the appearance of goosebumps. Within the Dermis there aresensory nerves that detect temperature. We also have an insulatory layer of fat in the subcutaneous.
Our skin is waterproof so absorbs very little, the only things that can permeate the skin are medications, this includes patches such as Nicotine and HRT and Essential oils (see Aromatherapy articles on Blog) COSMETICS CAN NOT.Do not believe the hype and sales talk ladies if it could be absorbed by the skin you you have to go to your Doctor for it and it would need to be licensed as a Medicine.
Our Skin is protected by sensory nerves that alert us to pain, pressure, touch, heat and cold, it is waterproof largely impermeable except to the substances above, fairly tough and it with its layer of fat below the dermis in the subcutaneous layer keeps us warm, protects our organs and bones, gives us shape. As fore mentioned the Acid Mantle helps protect from bacteria as bacterial growth is inhibited in its slightly acid environment. Melanocytesspecial little cells in the dermis increase as a result of UV light and give us tanning, the epidermis also thickens to help protect our skin. Also in the skin are mast cells and when they are damaged, they produce histomine, it gives the characteristic itching a weals associated by allergies, its function is to stimulate blood to the skin to repair and maintain it. However with allergies the body is hypersensitive producing this effect.
The skin also excretes some toxins through sweat but this is very very minimal, so do not believe the hype of some sales people who will suggest you have a detoxifying foot bath that will rid you of toxins as it changes the water to a dirty brown colour. Again this is sheer hype and nonsense for if ridding the body of toxins was that easy we wouldn't have a need for Dialysis Machines for those suffering kidney failure. It is the Liver, Kidneys and large Intestine that detoxify us.
Vitamin D is also formed in the skin as a result of the action of UV light acting on 7-dehydrocholesterol present in the skin, so everything in moderation we do need some sunlight.
SKIN CARE THE EFFECTS OF UV LIGHT
The effects of ultra-violet on the skin are a mixed blessing!
Some is beneficial, necessary for the formation of vitamin D, some is harmful. Much of what happens to the skin as a result of ultra-violet light is the result of the skin trying to protect itself and the body inside from the harmful effects of an excess of the rays; the skin is quite effective at preventing the rays penetrating deeply into the body.
The Stratum Corneum is a major factor in this prevention (see diagram below)
Reflection of rays by layers of the Stratum Corneum
The Stratum Corneum is maintained at such a thickness that with the ‘usual’ intensity of ultra-violet falling on it, very little passes through and no damage is caused to the live cells beneath. The Stratum Corneum of exposed parts of skin such as the face, neck and hands will be thicker than those parts normally covered by clothing.
However, exposure to higher than normal intensities of ultra-violet will allow sufficient rays to pass through the epidermis possibly to cause damage to the living cells underneath.
Penetration of Ultra-Violet Rays into the Skin
In a skin, which has active melanocytes producing melanin pigment granules, this extra ultra-violet will develop the colour of this melanin, resulting in a Tan.
But not everyone’s skin is in such a state of readiness; their melanocytes may be inactive, as a result damage will be caused to the live cells. The result reddening, discomfort, may be even blisters and peeling i.e. Sunburn.
Regardless, more UVB rays will penetrate to the Stratum Germinativum to stimulate its dividing cells into greater activity, this will produce new epidermal cells at a more rapid rate and this will eventually thicken the Stratum Corneum, thus helping to reflect UV rays.
The general increase in the skin’s metabolism reflects throughout the body in creating ‘a feeling of well-being’.
The physical, physiological and psychological effects of Ultra-Violet
Beneficial effects:
- Vitamin D production
- Stimulation of Metabolism
- Tonic Effect
- Has slight Germicidal effect on the skin
- Causes hyperkeratinisation (thickening described as above), which is thought to help with some skin conditions such as Acne Vulgaris and Psoriasis.
Screening responses against excess:
- Suntanning
- The irritant effect of sunburn
- The thickening effect of the Stratum Corneum
Damaging effects:
- Short term – Sunburn
- ***Long term – Premature aging, thickens the epidermis giving a ‘leathery’ appearance, irreversibly damages Collagen and Elastin fibres, causes dehydration, can cause allergic reactions, can produce dark pigmentation patches; Skin Cancer.
Vitamin D Production
A normal varied diet including dairy produce will supply all the vitamin D required; however through sunshine the vitamin may be made in the body with the help of ultra-violet.
In the body there are two substances, which can be converted into vitamin D, these precursor substances are 7-dehydrocholesterol and ergosterol. When vitamin D is required these substances are moved to exposed skin where using ultra-violet energy these substances are converted to Vitamin D.
The potential for making vitamin d in the skin is so enormous that merely exposing the face for less than an hour on an overcast December day will make all that is required for the day, the body is able to regulate this however so a days long sunbathing will not cause over production.
***How too much sun and UV light damages and ages the skin
So a little is good for us but too much has the opposite, sadly skin cancer is on the increase, we always think it won't happen to us, no matter what colour our skin is we can burn albeit the palest skins burn the easiest.
There are two types of skin cancer, a slower growing type often known as a rodent ulcer (basal cell carcinoma), this tends to be found across the cheek bones and under the eyes and on the nose and can be successfully treated since it is relatively slow growing. However the deadliest type of skin cancer is the malignant melanoma
Types of malignant melanoma
Skin cancer is broadly classed as either non-melanoma, accounting for about 90 per cent of cases, or melanoma, which is generally faster-growing.
These cancers grow from the layer of melanocytes – cells that produce pigment that protects the body from sun damage – below the surface of the skin.
If not caught early, the cancerous cells can quickly grow deeper into the layers of the skin, and then into the blood vessels and lymph channels (tiny tubes that carry lymph fluid, part of the immune system, around the body).
At this point, melanoma cells may travel to other parts of the body, causing tumours elsewhere, known as metastasis. In the early stages, treatment involves surgery and sometimes radiotherapy. More than 90 per cent of these cases are curable. However, patients whose cancer has spread rarely survive longer than a year.
Symptoms of melanoma include moles growing bigger, having irregular edges, or changing shape. Lesions that bleed, itch, crust over or are pink should also be checked by a specialist, as should moles that have at least two different colours or grow darker.
Use the chart above and if you suspect any changes to you skin don't be afraid to go and see your doctor, it could save your life.
Above all treat the sun with respect and common sense, know your limits for your skin type and don't allow yourself to burn for it's better to be pale and interesting than leathery and deadly
