Issuu on Google+

Advance Level

Library A skin type, a place, a photoprotection

1.

Did you know that skin is the most extensive organ of the human body? If we take into account that an organ is a structure of tissues forming a group in order to perform a task, the skin is the most extensive one of our body, since in adults it measures between 1.5 and 2 square meters and weights about 5 Kg. But, what task or function does it carry out? The skin, since it is an impermeable and flexible layer, protects us from the external world and helps us keep far from harmful germs. Furthermore, it is sensitive to the touch sense, heat, cold and pain, fact that let us know what is happening around us. But we have to keep in mind three of its most important functions related with solar rays:

1 It uses solar light to produce vitamin D. Vitamin D allows our bones and teeth to grow strong and healthy, since it helps them absorb calcium and phosphorus. 2 It controls body temperature. When it is hot, we sweat more and when this sweat evaporates we loose heat. And that way we prevent body temperature from increasing. 3 It protects us against harmful solar rays. There is a type of rays that, in spite of the fact that only a small amount of them arrives to the Earth, produces a harmful effect on the skin. They are the so-called ultraviolet rays, and there are two types of them: UVA and UVB.

A skin, a place, a photoprotection

1


Advance Level

Library

2.

How does skin protect us from UVA and UVB rays?

In order to fulfill all its functions, the skin has three layers: The epidermis (exterior and protective), the dermis (intermediate and thicker) and the hypodermis (made up by adipose tissue). The epidermis is the superficial layer of the skin. It has a group of dead cells that constantly detach and that protect other live cells underneath. Among them we find the melanocytes, which have inside a pigment called melanin, which gives our skin its color, but which above all protects us against radiation. It is a natural shield against radiation. The intermediate layer of the skin, the dermis, contains fibroblasts (cells that provide resistance and elasticity to the skin), nerve endings and blood vessels. The hypodermis is the deepest layer; it is the adipose tissue that acts as an energy reserve and thermal insulation. When you expose yourself to the sun, ultraviolet radiation (UVA and UVB) penetrates

Epidermis

Dermis Hypodermis

A skin, a place, a photoprotection

2


Advance Level

Library through the layers that make up your skin and damage it. UVB rays penetrate just a little into the skin (70-80% remain in the epidermis) and they can cause the typical burn or the defenses of our organism to decrease. On the other hand, UVA rays reach the dermis and cause the skin to age more quickly, bringing on the appearance of marks, wrinkles, etc and solar allergies. This kind of rays can even enter through the window, the car’s windshield or light clothes. Skin acts as a shield by isolating your body from the exterior and tries to protect it against the attack of UVA and UVB rays in three ways:

1 By producing melanin. The epidermis has some cells known as melanocytes which produce melanin, a pigment that is responsible for the color of our skin, hair and eyes. The differences in the skin color of the different phototypes are due to these cells, the main tasks of which is blocking ultraviolet rays in order to prevent them from damaging skin cells. When you expose yourself to the sun, your body produces more melanin as a defense strategy against the sun, and that is why you get tanned. 2 By increasing the number of skin layers. With the “protective shield� thicker, ultraviolet rays have it more difficult to penetrate the skin and damage it. 3 With sweat, because it not only helps us decrease our skin temperature, but it also acts as solar filter with a low protection level.

A skin, a place, a photoprotection

3


Advance Level

Library

3.

Thus, if I have a fairer skin color, am I less protected against sun rays?

Skin types with the less capacity to synthesize melanin are the fairest ones and the most sensitive ones against harmful effects of solar radiation. Depending on the amount of melanin that our skin has and its capacity to produce it, as one of the methods of protection against sun exposure, we can classify people within what is known as phototypes. According to the North American dermatologist Dr. T. Fitzpatrick, we can classify in 6 the existing skin phototypes. In the following table the main characteristics of each phototype are shown, the action of the sun on the skin and the tolerance of solar light of each one of them:

A skin, a place, a photoprotection

4


Advance Level

Library

Phototype

Phototype 1

Characteristics of the skin, the hair and the eyes

Action of the Sun on the skin (without protection): burns and tan

Tolerance to solar light

These are people with a very fair skin color (milk white), blue eyes and freckles on the skin

They present intense solar burns, they virtually never get tanned and their skin detaches intensely

Very sensitive to solar light

Their skin is white; they have blond or red hair, blue eyes and freckles

They easily and intensely get burnt, they get a little bit tanned and their skin detaches remarkably

Sensitive to solar light

Their skin is fair, without freckles. They have blond or chestnut hair

They get moderately burnt and they progressively get tanned

Normal sensitivity towards solar light

They often have brown skin. Hair and eyes are dark

They get moderately burnt, they easily get tanned immediately when they are in the Sun

The skin has tolerance to solar light

These are people with brown skin and dark eyes and hair

They seldom get burnt and they easily and intensely get tanned; they always have an immediate reaction to the tan

High tolerance to solar light

Black people

They never get burnt and they get intensely tanned, they always have immediate reaction to the tan

Very high tolerance to solar light

Phototype 2

Phototype 3

Phototype 4

Phototype 5

Phototype 6

A skin, a place, a photoprotection

5


Advance Level

Library

4.

Are there any other important factors I must bear in mind in order to protect my skin?

Phototype is one of the factors that determine the tolerance towards solar rays, but there are other factors that also have an influence. • Moment and place you are at The sun strikes the planet’s surface vertically when we are in certain areas of the world, such as the tropical regions, during spring and summer or during the central times of the day; in these places and moments is when the sun is the most dangerous. On the other hand, you must bear in mind that ultraviolet rays are more powerful in certain places of the Earth. The mountains is one of these places, since every 300 meters height the amount of rays you can receive increases in 4%. * You must also take into account the type of ground you are at, since rays are capable of rebounding against some surfaces and by doing so they increase their harmful effect on your skin. You must be very careful when you are in the snow (80% rebound), in the sand (25%), water (10%) or grass (10%). Furthermore, you must take into account that you also receive UVA and UVB rays on the days it is cloudy. The clouds just stop 10% of ultraviolet rays, and therefore on cloudy days, in spite of it not being so hot, the biggest part of rays that arrive to the skin can deteriorate it.

• The age Children skin is finer and more sensitive than that of adults, the action of the sun dries it more easily and it still hasn’t completely developed the necessary defenses for the attack of the sun. If to all that you add up the time they spend outdoors, you must be very careful with the sun.

A skin, a place, a photoprotection

6


Advance Level

Library

5. Thus, how can I protect myself against ultraviolet rays from the sun?

Photoprotectors prevent your skin from getting damaged and allow you to enjoy the sun more safely, since they have a series of substances (solar filters) that help stop the action of UVA and UVB rays by means of their “Photoprotection Action�. They disintegrate them by means of chemical solar filters and rebounds them with the mirror effect (Physical solar filters). If you look at it carefully you will see that in the container of the photoprotector there is a number written big: 50+, 30, 25, etc. It is the Solar Protection Factor (SPF) and it indicates the number of times the photoprotector increases the natural capacity of defense of the skin against ultraviolet rays. The higher this number is, the biggest protection you have against the attack of UVB rays from the sun, and therefore, the lowest possibility you have to get burnt.

A skin, a place, a photoprotection

7


Advance Level

Library In order to choose the SPF that best suits your needs, you must take into account all the factors we have mentioned before. 1 Phototype. If you have fair skin, you must use a photoprotector with a high Solar Protection Factor, 50+ for instance. If you have darker skin, you don’t need to use such a high SPF. 2 The place and the moment of the day. If you are at the beach, in the mountains or in the snow, or you are exposed to the sun between 12pm and 4pm, you will have to use an even higher SPF, even if it is cloudy.

Keep in mind that if you are a child, your skin is even finer than that of an adult and since you spend more time outdoors, you will have to use a specific photoprotector for your skin type and with a higher SPF than that for an adult. Keep in mind that you must consult your doctor or pharmacist, who shall recommend the photoprotector that best suits your needs, since all of them protect skin against UVA and UVB rays, but each one of them does it in a different way.

In addition to the photoprotector, please remember that you must wear a T-shirt, cap, sunglasses and sunshade (if you go to the beach). It is very important that you apply the photoprotector properly so that its power does not decrease. Apply the photoprotector 30 minutes before leaving home and on dry skin. Smooth a sufficient amount for the whole body, and apply it even on the ears, hands and feet. Don´t forget especially sensitive areas, like the nose, lips and feet. After playing at the beach or bathing, when your skin is dry again you must apply photoprotector again. Just one application is not enough for the whole day long.

A skin, a place, a photoprotection

8


Isdin ing sup biblio unapielunlugar