The World of Skin Care

 

an on-line reference by Dr. John Gray,

provided by the P&G Skin Care Research Center

 

A skin diagram of the skin layers

Look at your face in a mirror. What do you see?

     At first sight your skin looks like a simple, decorative covering for your body, but it is far more than this. For instance, parts of it develop from the same tissues as the brain, and remain directly connected to the brain by nerves. Skin is a vital outpost of the nervous system and is the closest contact we have with the outside world. Our sense of touch operates through our skin: we feel pain and changes in temperature. The lips, which are part of the skin, are amongst the most sensitive areas of the body.

     Skin is not just a simple flat sheet, but is composed of several skin layers. The very top skin layer is quite tough and, although microscopically thin, is our 'hide'. It is being constantly worn down and replaced. It plays a vital part in preventing excessive loss of moisture from the body, and helps to give healthy skin its attractive appearance. The deeper layers contain all the structures that give skin its strength and elasticity, and are home to important structures like the hair roots and sweat glands.

     As we age the natural strength and elasticity in our skin layers decline, with the result that gravity makes it sag and wrinkles develop. Although certain skin care products make wild claims to be able to 'restore' youth, there is no evidence that cosmetic products can prevent this natural decline of skin elasticity - we can only help to preserve what we have. It is mostly the damage to the deeper layers that will determine how our skin looks as we get older, and this is largely self-inflicted because we over-expose ourselves to the sun.

     Before we can discuss how to take care of skin we have to understand what it is and how it works.

A skin diagram: What skin looks like

Seen from a distance, skin layers may look perfectly smooth. But what we actually see is dependent on several factors, including the state of the very top layer, the type and amount of pigment in the layers beneath and the state of the tissues and the blood vessels in the deeper skin layers.

skin diagram of the skin layers

This skin diagram shows the complex structure of skin layers below the surface, seen here under a microscope

 

As we get nearer it becomes obvious that the skin layers are not absolutely smooth and perfect.

     If we look even more closely we will see that the surface is marked by a network of tiny furrows of variable sizes which divide the surface into rough rectangles. These change shape during movements of the skin. In some areas, such as the hands, movement would not be possible without the flexibility afforded by these furrows.

closeup view of fine lines and pores in skin

 

Looking closely at older skin reveals fine lines and pores

The 3 skin layers: epidermis, dermis, subcutaneous fat

The skin is made up of three distinct layers.

     The top layer is called the epidermis. (The word epidermis, and the name of the other main skin layer, the dermis, both come from the name used by the ancient Greeks for the skin, derma. From this we also get the word dermatologist, meaning a doctor who specialises in skin problems.)

    The epidermis is translucent. That is, it allows light to pass partially through it, rather as frosted glass does. The epidermis does not contain any blood vessels but gets its oxygen and nutrients from the deeper layers of the skin.

    At the bottom of the epidermis is a very thin membrane, called the basement membrane, which attaches the epidermis firmly, though not rigidly, to the layer below.

    The second layer lies deeper and is called the dermis. It contains blood vessels, nerves, hair roots and sweat glands.

    Below the dermis lies a layer of fat, the subcutaneous fat. The depth of this layer differs from one person to another. It contains larger blood vessels and nerves, and is made up of clumps of fat-filled cells called adipose cells.

    The subcutaneous fat lies on the muscles and bones, to which the whole skin structure is attached by connective tissues. The attachment is quite loose, so the skin can move fairly freely. If the subcutaneous tissues fill up with too much fat the areas of attachment become more obvious and the skin cannot move as easily -this is what gives rise to the notorious cellulite.

    The junction between the epidermis and the dermis is not straight but undulates like rolling hills - more markedly so in some areas of the body than others. A series of finger-like structures called rete pegs project up from the dermis, and similar structures project down from the epidermis. These projections increase the area of contact between the layers of skin, and help to prevent the epidermis from being sheared off. They are not present in the skins of unborn babies but rapidly develop after birth, and are very noticeable in a young person's skin when it is examined under the microscope. As skin ages they get smaller and flatter.

    Networks of tiny blood vessels run through the rete pegs, bringing food, vitamins and oxygen to the epidermis. In pale people these vessels can be seen through the epidermis, particularly if the veins widen (so-called 'broken veins'). If the blood carries plenty of oxygen it will be pink and the skin will tend to have a rosy color. If the blood is running sluggishly and has lost most of its oxygen the skin will look bluer. These blood vessels respond to temperature changes. They open up in hot weather, bringing lots of red blood cells - and hence a pink flush -to the skin, and close down in the cold; this is why cold skin often looks blue.

This shows all three skin layers: epidermis, dermis, subcutaneous fat

(Left) One of the rete pegs that project into the dermis; (right) as we get older the rete pegs get smaller and flatter - this means the epidermis is more easily sloughed off in old age

 

Skin Care Myth:

Cucumbers on eyes

Cucumber contains a special ingredient that helps to reduce swelling around the eye or bags under the eyes.

cucumbers on eyes

Pleasantly cooling, but no sorcery involved!

Fact: More than 90% of the cucumber consists of water. It is the cooling effect of the water in the cucumbers on eyes, together with increased humidity, that reduces the swelling. Some products contain extracts of cucumber, which in high concentration may help to improve the hydration of the skin. Gentle massage also helps.

 

The epidermis

All the cells in the epidermis originate ultimately from a single layer of basal cells, called the basal layer, which sits on the basement membrane. The 'daughter cells' produced by this basal layer gradually move upwards, lose their central nucleus, and start to produce skin proteins called keratins (hair is made up of a similar, but harder, material) and fats called lipids. They are now known as keratinocytes. As they move upwards through the skin thickness their form slowly changes. The altered cells form distinct layers, which naturally blend into each other.

 

Skin Care Myth:

Skin cells and skin repair

It is important for skin regeneration to have at least eight hours of sleep a night. While we are sleeping new skin cells are formed, waste is removed and the skin prepares itself for the day ahead.

Fact: Skin repair continues day and night, and is not dependent on the length of sleep.

the layers of the epidermis

Skin pigmentation

The keratinocytes are not the only cells in the epidermis.

skin pigmentation is determined by the melanocytes of the epidermis

The melanocytes of the epidermis are crucial in determining skin pigmentation (color)

 

distribution of melanin in the epidermis

The distribution of melanin in the epidermis.

 

Melanin

    There are two forms of the pigment melanin: eumelanin granules, which tend to be round and smooth and produce black and brown skin pigmentation, and phaeomelanin granules, which are more irregular in shape and which are more prominent in lighter skins, particularly in association with red hair and freckles.

    These two forms of melanin are often both present together, and occur in varying proportions.

The dermis

 

Beneath the epidermis lies a much thicker skin layer, the dermis. The dermis can be as much as 3000 micrometres thick.

   The dermis is composed largely of the protein collagen. Most of the collagen is organised in bundles running horizontally through the dermis, which are buried in a jelly-like material called the ground substance. Collagen accounts for up to 75% of the weight of the dermis, and is responsible for the resilience and elasticity of the skin.

     The ground substance of the dermis, seen under the microscope;      it is an almost unstructured colloidal gel.

 

The collagen bundles are held together by elastic fibres running through the dermis. These are made of a protein called elastin, and make up less than 5% of the weight of the dermis. Despite their name, they are not involved in the natural elasticity of the skin.

 

As skin gets older, it loses some of its elasticity and ability to retain water. Collagen production declines as does subcutaneous fat, and the facial muscles start to atrophy.

 

     Massed collagen and elastin fibres in the dermis

 

Keloid scars

keloid scar

Scars in older people tend to be cosmetically better

 

Sometimes the skin cells go on working at the repair process for much longer than necessary, so that far too much scar tissue is formed. This produces a permanent raised scar called a keloid. Keloids are common with certain types of skin, particularly in young people and those from an African background. They can be injected with steroids by a doctor, which sometimes helps. Cutting them out is seldom effective, and usually makes them worse. Eventually they decrease in size.

 

Skin creases

 

In many regions of the body the skin is separated from the muscles by loose fatty tissue (of variable depth) and moves very easily. In other areas it is anchored to the bones. This is most obvious in the palms of the hands, where the skin is arranged so that it closely follows the movements of the fingers. Some of these creases form while a baby is still in the womb, or very soon after birth.

  Folds and creases are also found on the face even in very young babies, as the skin accommodates the movements of the muscles of the face. In the face of a very fat person the subcutaneous layer of fat becomes thick and bloated, and reduces the appearance of these creases.

The subcutaneous fat layer

The subcutaneous fat layer cushions the dermis from underlying tissues such as muscle and bones.

   As we have seen, this layer consists of cells containing fatty deposits, called adipose cells. The blood vessels and nerves it contains are larger than those in the dermis. It may also house the hair follicles when they are in the growing phase.

   One of the functions of this fatty layer may be to act an insulation to conserve body heat. The human body stores fat as an energy reserve, in the same way that some animals store fat for winter when food supplies are likely to be short. Unfortunately the numbers of people with excess fat are increasing, thanks to their genetic predisposition together with habitually eating the now abundant sources of food. An excess of stored fat is seldom due to hormone problems, although as we get older fat deposition naturally increases as our metabolisms slow down. Getting normally heavier is therefore not necessarily due to us eating more food - just to eating.

   Fat is stored outside the muscles. Although calorie reduction as part of an overall plan helps to make us slimmer, specific remedies to improve muscle tone in the tummy by exercise do not necessarily help to reduce the fat in that area. Distribution of fat in the body differs between men and women: in women it is stored mainly in the buttocks and thighs, and in men in the abdominal wall (the notorious 'beer belly').

   The subcutaneous fat is organized into fat lobules, which are separated by collagen fibres. When these lobules become grossly distended and engorged by fat they adopt characteristic patterns (cellulite), in women particularly on the bottom and thighs where the skin is tethered down to the underlying muscles. These patterns tend to develop from the teens onwards

Causes of cellulite

cellulite

The dreaded cellulite is the result of genetically determined deposition of fat from the teens onwards.

 

   There are no magic cellulite treatment remedies for selective cellulite removal. It can only be reduced as part of an overall weight reduction program, together with cutting back on calorie intake and increasing exercise, although some fruit acid creams may help to make cellulite temporarily less obvious.

 

Special skin structures

 

The skin contains certain important structures with special functions. The lips are specially developed as sense organs. The sweat glands help to regulate body temperature. Most of the hairs on a human body have no real function and are a relic of when our ancestors needed warmer 'coats'.

 

The sebaceous glands

 

Sebaceous glands are part of the tiny structures - hair follicles - that generate hairs. These glands produce oil, or sebum, which is a mixture of waxes and fats. The glands empty through minute tubes called ducts. Sebaceous glands occur in the skin of every part of the body except on the palms and soles.

Fingernails

   The nails are flattened, elastic structures which are relics of claws. They consist largely of compressed keratin, and are in fact greatly thickened areas of the epidermis. The keratin of the nails is derived from the stratum lucidum (meaning 'the clear layer'), which lies just below the stratum corneum

. The keratin of the nails can absorb large amounts of water, particularly during a warm soak. This is why nails are softer, and much easier to cut, after a bath.

    On average, fingernails grow by half a millimetre or so a week; toenails grow a little more slowly. Growth is said to be quicker in the summer than in winter, and is most rapid in the longer digits.

   The white flecks that sometimes appear in the nails are due to minute air bubbles in their structure.

fingernails

Well-cared-for nails enhance beautiful hands

Gender-related features of skin

   There are subtle differences between the skins of men and women.

The stratum corneum tends to be thicker in men than in women. Moreover, in men the total skin thickness is about 25% greater than in women. The collagen content of skin is directly related to sex: male forearm skin, for example, contains more collagen than female skin at the same site at all ages.

   There is also a difference in the composition of the sebum. Also, throughout their lives men produce more sebum than women do, and the lipid film on the surface of their skin is therefore more pronounced: as a result, desquamation in men is a slower process than it is in women.

   There are also differences in sweat secretion between the sexes. Men have fewer sweat glands, both eccrine and apocrine.

   Skin aging has different features in men and women.

Skin has many functions, and is far more than a mere decoration for the body. Some of these functions are so important that unless most of the skin is working efficiently, we will die.

    This is the reason why second- or third-degree burns are so serious. When the skin is destroyed over a large area, there is no way of controlling the rate at which water is lost to the outside environment, or of regulating the temperature of the body or of controlling infection. Someone who has lost over half the skin this way is unlikely to survive.

    Although we think of the skin as a single organ, the epidermis and dermis have to some extent separate functions. The function of water conservation is however dependent on both; the role of the stratum corneum in this field is absolutely vital, as it acts as a semipermeable barrier and allows us to survive in a hostile environment.

Functions of the epidermis

The epidermis has three principal functions:

  • protecting the body from the environment, particularly the sun
  • preventing excessive water loss from the body
  • protecting the body from infection.

Protection from the environment

The sun produces enormous amounts of heat and light, some of which reaches the earth. Without this heat and light no life could ever have evolved.

    Unfortunately the sun also produces less beneficial rays, which are completely invisible to us, called ultraviolet radiation. (Sun beds also expose their users to these rays.) Part of this radiation is reflected by the stratum corneum at the skin surface, part is absorbed by the melanin

in the epidermal cells, and some is scattered within the skin. All three processes contribute to the vital function of protecting the nuclei of the cells in the epidermis and the collagen of the dermis.

This scattered radiation creates a lot of high-energy particles, which are called free radicals. Free radicals are very reactive, and attack the constituents of the skin: this is why over a long time ultraviolet radiation produces so much damage.

 

Prevention of water loss from the body

Throughout our lives our bodies naturally lose water by constant gentle evaporation through our skins (transepidermal water loss, TEWL), although we are unaware of the process. Preventing excessive water loss is exceptionally important in itself - both to the skin itself and to the body as a whole. In the normal epidermis the water content gets less the closer we get to the surface. Water makes up to 70-75% of the weight of the basal layer, but only 10-15% of the stratum corneum.

    The stratum corneum is a particularly important barrier to the control of moisture loss

 

It is also a highly effective barrier against the outside environment, being tough but flexible provided it is well hydrated. If its water content falls below 10% it becomes dry, less flexible and increasingly prone to damage, breakdown and infection.

    The epidermis as a whole is about 35 micrometres thick when dry, but can swell to 48 micrometres on full hydration. This depends more on the humidity and temperature of the surrounding air than on how much we have drunk!

 

SKIN MYTH

Drinking six or eight glasses of water a day will keep skin moisture levels high, and is an essential factor in renewing cells and hydrating the skin to prevent wrinkles from forming. It also helps to detoxify and remove waste.

Fact: Drinking more will not cause water to enter the skin selectively, unless the person is seriously dehydrated. Normal skin is well hydrated naturally. The excess water goes into all the tissues of the body, and ultimately to the bladder!

    Detoxification of the body is carried out by organs such as the liver, which do not need vast amounts of water to function.

Preventing infection

The natural layer of oil-in-water emulsion on the skin is the first barrier against invasion by micro-organisms such as bacteria, fungi and yeasts. The stratum corneum provides the next level of defence.    White blood cells in the skin can capture and destroy bacteria invading the epidermis. As a result pus may form.    The epidermis also contains special defence cells (Langerhans cells) which are spread out amongst the keratinocytes. These cells mop up invading foreign substances that have found their way into the body, and take them off to special white cells (lymphocytes) in the lymph glands. Here they are neutralised.

Langerhans cell

A Langerhans cell in the skin.

    An important element of defence concerns chemicals. If a chemical such as nickel is constantly absorbed through the skin, say from a button on one's jeans, it is first taken up by the Langerhans cells; later, however, special lymphocytes called T-cells make antibodies to that chemical. This can in time lead to an allergic skin reaction at the site of the button as the T-cells rush to meet the invading chemical.

Functions of the dermis

These include:

giving mechanical protection to the body from bumps and knocks; the collagen has an important role in this function.

Sweating

One of the important functions of skin is in helping to control body temperature.    All primates (a group that includes apes and humans) have glands in the skin from which they produce sweat  and control body temperature by evaporation (horses have them too). This sweat, which we don't notice, is called insensible perspiration. Evaporation needs heat energy, so evaporating sweat removes heat from the body and keeps down the body temperature (a process called thermoregulation). Sweat production is a response sometimes to external temperature changes, sometimes to internal stimuli - such as a highly seasoned curry! - and occasionally to stress, as a reaction to increased production of adrenalin.

(left) blood vessels in the dermis; (right) the vessels widen when warm

Body temperature regulation by blood flow control: (left) blood vessels in the dermis get narrower when cold, so limiting the amount of heat brought by the blood to the skin surface and lost; (right) the vessels widen when warm, so that heat is brought to the surface and escapes.

 

    Control of body temperature through sweat production is essential for life. Unfortunately this mechanism encourages effects which are now considered unacceptable, such as excessive wetness and unpleasant markings on clothing, and body odour (malodour).

    Most of the sweat produced by the body comes from the eccrine glands. Up to two litres can be lost in an hour! While its primary function is temperature control, eccrine sweat also provides a useful method of removing acids and some waste products (toxins) from the body.

    Men sweat more than women do; on the other hand, women have a higher perspiration pH (pH 7) compared with men (pH 5.61).

Different skin types and their characteristics

As skin grows older, we start to see differences in its appearance - and not only differences in our own skins but differences between people of the same age. The changes are determined fundamentally by our inherited skin type, its response to its environment and sometimes our overall health

Skin type

Unexposed skin color

Sun response


I

white

always burns, never tans

II

white

always burns, tans minimally

III

white

burns minimally, sometimes tans

IV

light brown

burns minimally, always tans well

V

brown

rarely burns, tans darkly (Asian skins)

VI

dark brown

never burns, tans darkly (African skins)

 

One way in which scientists define skin type is according to how it responds to exposure to the sun.

    The system of classifying skin according to its type, shown in the table above, was developed on a two-factor basis: hair color and the ability to tan. Classification under this system also indicates the people who are especially prone to develop skin cancer. The six-point scale is based on the answers people give when questioned about how they react to sun exposure.

    Individuals who are types I and II have skin more likely to burn and have difficulty developing a tan. It is also these people who are at highest risk for the development of skin cancer. During the last two centuries or so, many people of this type have moved to sunny climates like those of Australia and South Africa and are now at a much higher risk of developing skin cancer than if they had stayed in Europe.

Skin type descriptions

Another way of classifying skin types becomes evident when people are asked to describe how they view their skins. For practical rather than necessarily scientific proposes, they will often describe their skin type as either normal, dry, greasy or mixed.

    In the next part of this chapter we discuss each of these descriptions in turn.

 

Normal skin

 

The characteristics of so-called 'normal' skin can be summarised as follows:

  • a clear appearance
  • an even color
  • feels neither tight nor greasy
  • soft and supple to the touch
  • a high degree of elasticity.

Normal skin may be said to have nothing obviously wrong with it, and no sensations of discomfort. It results from a balance of the normal skin functions (including new skin cells being formed and old ones being lost, together with well-controlled water loss, sebum secretion and sweating). This creates a balanced state of suppleness, elasticity, color and hue which is often characteristic of pre-adolescents.

    Normal skin can quite quickly become 'abnormal', however. Failure to look after it, or abuse by sun, wind or cold, may lead to dry and damaged skin and ultimately the risk of premature development of lines and wrinkles.

Dry skin

  • feels tight and irritable
  • often looks flaky
  • often develops fine lines around the eyes
  • tightens after washing with soaps or detergents or prolonged exposure to low humidity.

Dry skin is characterised most of all by this sensation of tightness, with the skin feeling rough and scaly and visible lines developing. At its worst it may look cracked. The problem lies in poor epidermal function and damage to the water/lipid barrier film, shown by an increase in the rate of transepidermal water loss (TEWL).

    Patches of dry skin may arise from apparently normal skin, or sometimes even greasy skin, that has been temporarily dried out, whether by sunburn, or by exposure to extremes of climate (cold, heat, wind or dryness) or to chemicals such as detergents and solvents or to air conditioning. In young people the main problem of dry skin is a reduced production of sebum.

    Dryness is a significant problem associated with mature skin as hydration ability progressively decreases and the skin's mechanical properties deteriorate, with loss of suppleness and flexibility

 

Sensitive skin

 

In addition to these recognised types of skin, many people believe that they have 'sensitive skin'.

    Doctors and scientists are not completely agreed about what 'sensitive skin' is, but it may generally be considered as skin which is easily irritated. It is more commonly associated with people with type I skin, and probably has a genetic element.

    Some people with this condition cannot tolerate contact with any cosmetic products, however well-formulated they may be.

 

Sensitive skin can be associated with a medical condition called atopy, where people have an inherited predisposition to eczema, hay fever and asthma.

Atopic skin. About 15-20% of the population have the genetic ability to develop eczema, asthma and hay fever. The figure has risen considerably in the last few decades.

In several surveys, up to 70% of women said they thought they had 'sensitive skin'.

 

Greasy (oily) skin

 

Greasy skin (sometimes called seborrhoeic skin) generally appears at puberty although in a few people it starts much earlier, from the age of six upwards. It is rare after the age of 35. It involves only the upper part of the body, where greater numbers of sebaceous glands are found.

     This type of skin is particularly common in adolescents and young adults. At this age there is in both sexes a dramatic increase in sebum production under the influence of the male sex hormones. The extra sebum gives the skin a shiny appearance, especially on the nose and forehead. The epidermis tends to thicken, due to increased keratin production, and the pores dilate. As a result the skin feels rough and irregular.

 

Mixed skin

 

Mixed skin (often called combination skin) is characterised on the face by thickened, shiny skin associated with patches of dry skin

Truly sensitive or atopic skin may:

  • feel very tight after washing
  • have a naturally high TEWL rate
  • react to many external stimuli by becoming red and blotchy
  • be prone to developing dry flaky patches.

Variation with site on the body

 

Whatever the type of skin, its state and function will differ from one part of the body to another even in the same individual, and will change from time to time. For example, the face, forearms and hands are most exposed to the elements and may suffer from drying and cracking. The bottom is scarcely ever exposed and the skin there is almost always in near-perfect condition. To really see the differences in skin condition in one person, these are the two areas to examine!

    Another characteristic that shows considerable variation is the density of the sebaceous glands. There are many more sebaceous glands per unit area of skin in the upper part of the body (forehead >300 per cm²; chest 60 per cm²; upper back 80 per cm²).

 

    Another example of a variable characteristic is the permeability of the skin: the skin of the palms of the hands is less permeable than that of the forearm, which in turn is less permeable than that of the scalp.

    The rate at which the stratum corneum loses corneocytes as squames also depends on the body site. Squames are lost more rapidly from the forearm and back, for example, than from the upper arm and abdomen.

Factors affecting skin function

Environments that dehydrate the skin can considerably affect the skin condition, and hence its functions. Examples include centrally heated and air-conditioned homes and offices.

    Out of doors, sun and wind together may produce very severe drying effects, especially if they are experienced over a long period of time.

    Water and harsh household detergents and cleaning fluids are the most damaging factors of all, particularly to the hands. People who work as cleaners or apprentice hairdressers expose the skin of their hands to water and chemicals all day long, almost every day. This can result in chronically dry and chapped hands, which may result in a form of irritant dermatitis if left untreated. In turn they may become prone to develop allergies to products with which they come into contact, producing an allergic dermatitis.

Climate and skin condition

Climate can make a considerable difference to the state of all our skins. Where we live in the world, and whether we are adapted to the local climate there, may also be critical.

    The humidity of the air is important to the way we feel and how our skin condition fares. Humidity is largely determined by temperature: this is because the air can hold more water vapour at higher temperatures. In winter the air cannot hold as much water, and on a very cold day there is virtually no moisture in the air at all. This is why we can often see people's breath in frosty weather: as the warm, moist air from the lungs cools down, the water vapour in it turns into tiny liquid drops that form clouds.

    In hot weather, most of us find dry air more comfortable and pleasant than very humid air. The tropics are hot and humid, while Scandinavia can be warm and dry. Many people find hot, humid weather trying and difficult to tolerate: this is the kind of weather in which, in certain countries, seems to accentuate a tendency for riots to break out! The skin, however, prefers humidity to dryness.

 

Skin condition in winter

 

The condition of skin can change from day to day, and even from hour to hour. It may be affected by general health, by changes in hormones during the menstrual cycle and by the immediate environment. Skin that felt normal in the morning may feel greasy and uncomfortable after a day spent travelling in crowded trains and working in an office with rather inefficient ventilation.

 

    Skin needs to maintain water balance with the environment for ideal function. As we have seen, the epidermis, particularly the stratum corneum, acts as a partial water barrier, helping to regulate the amount of water in the skin. This barrier itself needs adequate water (more than 10%) to function properly.

 

Cleaning the skin after a day's work reveals how much sebum and dirt was trapped in it. Much of this has to do with the amount of moisture in the environment and the level of pollution.

 

    This water is used to ensure that the other vital part of the barrier, the lipid structures between the cells of the stratum corneum, is maintained in a fluid state. Damage to the stratum corneum - for example, by washing with harsh soaps, which removes both external and internal lipids - can disrupt this barrier and set up a 'vicious circle' of drying

Dry Skin in Winter

    In fact, skin has to fight a daily battle against the drying effects of the environment.

    But this drying effect is worse in the winter months. Although air in the winter months often feels damper, on average it has less relative humidity than in the summer - that is, humidity compared to that of the skin.

    In winter the difference between the concentration of water in the air and that in the skin exerts a considerable drawing force on water in the skin. If dry skin becomes drier, the lipid structure of the barrier tends to break up. As a result, water cannot be retained so easily. The cycle of water loss is set up again.

In the winter months, air has less relative humidity and the skin tends to dry more rapidly.

 

    Another factor is that the stratum corneum simply doesn't like the cold. Cold makes keratin stiffer and less flexible - you will probably be familiar with the 'tight' feeling that skin has in the winter.

    As a result of all these factors, skin tends to be drier and in worse condition in the winter months than at other times of the year. In extreme cases, this constant drying effect can lead to cracking, flaking and redness. In the winter, skin tends to lose the battle against the environment. That's when it needs to be looked after most.

    In the winter, a moisturizer can be regarded as essential to maintain healthy skin - even so-called 'normal' skin. As we will see later, a moisturizer performs several important functions. It enables lost water to be replaced, and then helps to keep it in the skin by the humectants (water-binding agents) that it contains

. One such is glycerol. Scientists have shown that humectants play a vital role in the skin by helping to maintain the lipids of the epidermis in good condition, vital to its water-retaining properties.

A good moisturizer will deliver water to the skin effectively and keep it in the skin for as long as possible.



Glycerol (often called 'glycerin'), one of the best known humectants, is an ingredient of nearly all moisturizers.

Coming in from the cold

 

Coming into a warm room from the cold outdoors will often restore a rosy glow to the skin and soften it to some degree. This is due to the blood vessels in the skin opening up in the warmth

The use of moisturizers on both hands and face is especially important in winter.

    This will not help to restore moisture, however. It may even encourage more water loss, since the air in centrally heated houses is often drier than that outside!

Sebum production in winter

Sebum (the lipid mixture produced by the skin's sebaceous glands) is produced at a fairly constant rate in each individual, though rates vary from one person to another and tend to be higher overall in the teenage years. It does not change in response to time of day or season, though sebum will obviously build up on the skin throughout the day. (This is why skin feels sticky at the end of the day.)

    Since sebum production is neither significantly lower or higher in the winter, there is no need to use a moisturizer with extra (or less) 'oil' in the winter to compensate for a lack (or excess) of sebum.

Skin appearance in winter

As we have seen , the skin's response to cold is to close down the small blood vessels in the dermis. This diverts blood from the surface of the body to the inside, and helps to check heat loss.

    The result can be that in cold weather skin loses the glow it normally gains from blood flow close to the surface, and it can tend to look dull and lifeless. Massaging with a moisturizer will help to stimulate circulation near the surface

Raynaud's phenomenon: bleaching of the skin caused by sudden shut-down of blood vessels - prevent it by wearing gloves in cold weather.

and give the skin more color, as well as improving the water content. You can do this as often as you need to - you can't over-moisturise!

Some people have a particular sensitivity to even slight drops in the air temperature, resulting in the ends of their fingers going white. This is called Raynaud's phenomenon: although it can be painful it is otherwise harmless.

The essentials of winter skin care

  • Use a good moisturising product during the day - it doesn't need to be a heavy cream, but it does need to hydrate well. Use it liberally and often.
  • At night, use a good night cream. Night creams are specially formulated with a higher lipid content than would normally be comfortable in the day, to help restore softness to the skin.
  • Do not wash with harsh soaps. Soaps dry the skin and exaggerate the effects of the cold. Use a good-quality mild cleanser formulated for 'sensitive' skin.

Stay warm! Keep well wrapped up, to help maintain a soft skin by preventing excessive TEWL

 

Some common skin problems

 

We all recognise that not everybody has beautifully clear skin. Some have dry and blotchy skin. Others have blemishes, too much pigment, or too little. In this chapter we describe some common skin problems that you may encounter.

Atopy and atopic skin

About 20% of the population have the inherited condition called atopy, which can lead to

 

various degrees of dry skin or even eczema. People with this problem need to take extra care of their skin.

   Atopic skin tends to have a higher than average TEWL and loses water readily. It can be very sensitive to irritants.

   No one knows the precise cause of atopy, except that it has a genetic component: 70% of patients with atopic dermatitis have at least one relative who suffers from either eczema, asthma or hay fever.

Atopic eczema

Atopic eczema is becoming steadily more common. Among those born before 1960 the reported frequency is only about 2%, but it rises to between 9 and 20% in those born after 1970. The reason for the increase is still a mystery: it may be a real effect due to living in a more protected environment, or simply the result of better recognition of the condition, or perhaps both. Eczema is common among small children. It is often suggested that the cause may be diet intolerance, but this is probably rarely so.

 

Treatment

 

A family doctor can advise on managing eczema, but long-term commitment to skin care will be needed. Eczematous skin requires constant moisturising, and harsh soaps should be avoided. Careful use of steroid creams on the body may be helpful, but these products should only be used under medical supervision.

 Eczema is made worse by scratching, and the facial eczema  that is  common among babies and toddlers is also  worsened by dribbling.

Hand eczema is very common, and is often associated with occupational diseases. In certain countries people with atopy are not permitted to take up hairdressing.

 

Eczema

In childhood eczema the dry and cracked skin often appears in the creases of the elbows, knees and bottom - the so-called flexural eczema

In adults, eczema tendsto form patches

In elderly people eczema can be associated with poor circulation in the legs: this is known as varicose eczema

Acne

Acne can affect all age groups, from a few months after birth to old age. During puberty, virtually all boys and 90% of girls will have some spots and pimples, which are usually mild forms of acne; nearly 85% of people aged between 12 and 25 will have had some acne.

   The psychological effects of acne can be severe in some people, who may feel disfigured and unattractive because of the eruptions on their skin.

   Many factors are concerned in the development of acne, including a hereditary

 

The early stages of acne: start using a specialised cleanser

every day.

predisposition and the presence of male hormones (in both boys and girls), which leads to increased sebum production and the presence on the skin of otherwise harmless bacteria called Proprionibacterium acnes. These multiply deep in the hair follicle and produce inflamed pus-filled spots.

Treatment for acne

Prevention is better than cure!

   The main aim of the treatment of acne is to prevent new spots appearing on the skin. Getting rid of existing spots is much more difficult: people having treatment are often disappointed because their spots don't disappear quickly. Acne sufferers need a great deal of patience!

   A regular cleansing routine using specially formulated products (available from pharmacists and retail outlets) can help to remove surface sebum and the bacteria associated with acne. If these products are conscientiously used on a daily basis they can help to reduce the number of spots that will occur in the future.

   People who already have mild to moderate acne should use products specifically formulated for this condition: these contain special ingredients for the prevention of spots, such as salicylic acid or benzoyl peroxide, which remove keratin and kill the bacteria. These will provide a treatment that can help to reduce the number of existing spots on the skin.

    In cases of persistent or severe acne a doctor should always be consulted: effective treatments are available, but only with medical supervision.

 

Acne Myths

SKIN MYTHS ABOUT ACNE

Chocolate and fatty foods cause acne.

 

Fact: This is just one of the many myths about diet and acne. It is true that acne is less common in some countries where diets are markedly different from ours, but this difference may be due to genetic factors. There is little scientific evidence to indicate that diet plays a significant role in the development of acne.

Sunlight exposure improves acne.

Fact: There is no conclusive evidence to show ultraviolet radiation improves acne. A tan may mask erythema (reddening of the skin) and provide some cosmetic improvement.

Poor hygiene causes acne.

Fact: If acne were caused by a lack of soap

and water, it would probably occur between

the toes. In fact, too much scrubbing and

friction aggravate acne.

 

Acne is a disease that mainly affects teenagers.

 

Fact: Many adults have acne or acne variants:

the condition can even occur for the first time in elderly people.

 

Cold sores and other common skin disorders

The following series of photos and descriptions shows some of the more common skin disorders, which may be medical or cosmetic,

together with an indication of what remedies (if any) may be helpful. We all see these conditions in our own skin, or that of others, from time to time.

 A cold sore is an eruption on the margin of the lips. It is caused by the virus herpes simplex, which lives in the body and escapes the immune system. Cold sores develop when the skin is damaged during a cold or after sunbathing. They can be suppressed by anti-viral creams available from pharmacists, but usually they die out even if untreated.

Angular cheilosis takes the form of small splits at the side of the mouth, made worse by licking. The cause is unknown, although the condition is often (wrongly) attributed to vitamin deficiency. It is eased by using lip salve frequently.

This scarlet bleb is a haemangioma, a harmless      collection of dilated blood vessels. It can be dealt
      with  easily by a doctor.

 

Shingles; chicken pox; impetigo

 

Shingles is a very common condition that is caused by the chicken pox virus, which lives on in everyone who has had the disease. It erupts in this typical line on the trunk or the face. Contrary to the popular myth, it is not contagious.

 

Chicken pox: these are the intensely irritating 'blisters' characteristic of this common childhood infection. It is probably not contagious for more than a day or two after the spots appear. There is no specific treatment other than to prevent scratching by applications of calamine lotion, to avoid damaging the dermis with consequent lifelong scarring.

Impetigo: a superficial skin infection, often seen around the mouth, nose and chin, especially in children. It is not necessarily due to poor hygiene.

Antibiotics can be prescribed by a doctor and will cure it rapidly

Rashes, scales and crusts

Urticaria, or 'nettle rash', is often associated with allergy since it looks like a reaction to stinging nettles. It forms acutely itchy swollen patches on the skin, which usually subside quickly although occasionally it becomes chronic. It can be caused by reaction to penicillin, certain foods, sunlight or even stress; it is sometimes caused by pressure from a tight garment, which is why it is often falsely attributed to washing powder residues in clothing.

    It can be treated by anti-histamine tablets or, if very severe, by steroids prescribed by a doctor.

 

Psoriasis: a common skin condition which is due to over-production of cells in the epidermis with incomplete desquamation: this is what causes the heaped-up skin areas and scaly patches. It is essential to get a doctor's advice

 

Cradle cap is an excessive desquamation resembling eczema. In infants it clears spontaneously, but in older children it may need treatment with special shampoo