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)
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.
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’.
Beneficial effects:
Screening responses against excess:
Damaging effects:
Vitamin D Production
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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:
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- 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
MPB copyrightIn 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
Maggie Brown (Author)
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