Skin.pptx

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• Beauty
• Further Education (Key Stage 5)

A&P theory

Skin

skin - Function, normal structure, growth cycle and repair, characteristics, diseases and disorders

• Describe the structure and functions of the skin

• Describe diseases and disorders of the skin

• Explain how natural ageing, lifestyle and environmental factors affect the condition of the skin and muscle tone.

• The human skin is an organ – the largest in the body.

• It is also known as the integumentary system, made up of the skin and its accessory parts, the oil and sweat glands, sensory receptor nerves and the hair and nails.

• The skin provides a tough, flexible covering, providing an effective barrier between the body and the environment. It achieves this through many different important functions

Normal structure of the skin

The skin has three distinct layers:

• Epidermis

• Dermis

• Hypodermis or subcutaneous.

The surface of the skin is covered by an acid mantle, which is a water in oil emulsion formed from a mixture of sweat and sebum. It makes the skin’s surface slightly acidic. It is also covered with mineral and organic substances, such as urea, lactic acid and amino acids. These substances make the skins surface slightly acidic.

epidermis – layers/ structures

The epidermis has five layers which are formed of sheets of cells. The cells are held together by a special adhesive and form tight junctions. There is still some ability for cellular movement between these tight junctions.

These five layers are called:

1 Stratum corneum (Horny layer)

2 Stratum lucidum (Clear layer)

3 Stratum Granulosum (Granular layer)

4 Stratum spinosum (Prickle layer)

5 Stratum germinativum (Basal layer)

The epidermis is made up of five layers, which are formed of sheets of cells. You can remember their names by using the following rhyme;

• Corny

• Lucy’s

• Granny

• Spins

• Germs

• The skin cells in the epidermis move upwards from the stratum germinativum ( where they are produced) to the stratum corneum (where they die). This process takes on average between 24 and 42 days. As we get older this process takes longer.

• The average thickness of the epidermis is 0.12mm.

• It is thickest on the soles of the feet (1.5mm) and thinnest on the eyelids (0.05mm).

• There are several different types of cells in the epidermis - each has a different

• function.

Layers of the epidermis

• Stratum germinativum (basal layer)

This is the deepest layer of the epidermis and forms a junction between the epidermis layer and the dermis. Skin cells are produced in the stratum germinativum in a process called mitosis which produces new epithelium cells. One cell remains in the stratum germinativum and continues to reproduce, while the other migrates through the layers to the stratum corneum where the cycle ends.

The stratum germinativum also contains keratinocytes and melanocytes.

The melanocytes formed in this layer play an important role in protecting the skin against harmful UV rays. Eighty per cent of the moisture required for maintaining a healthy skin surface is found in this layer.

Stratum spinosum (prickle cell layer)

The stratum spinosum is 8–10 layers deep. Keratin production begins in the stratum spinosum and is injected into the cells. The cells have a prickly appearance due to connecting threads called fibrils. This layer includes the Langerhans cells which help support our immune system.

Stratum granulosum (granular layer)

The cells take on a distinctive flattened shape and take on a granular appearance as a result of keratinisation. The cells begin to differentiate and become corneocytes, they lose their nuclei and organelles and the cell’s functions begin to decrease dramatically. This layer is 3–5 cells thick.

Stratum lucidum (clear layer)

This layer has flat transparent cells, hence the name ‘clear’ layer. There is no melanin present in the cells. The stratum lucidum controls the amount of water that can pass through the skin. This layer is not present in very thin areas of skin.

Stratum corneum (horny layer)

This is the outermost layer of the epidermis and is in direct contact with the environment. The skin cells are flat and no longer have a nucleus.

Their structure is very different from when they were produced in the stratum germinativum.

The dead skins cells are continually being shed. About 90 per cent of household dust is dead skin cells. The thickness of the corneum also varies with age, getting thicker as we grow older. This thickening makes the signs of ageing more obvious.

One major function of the stratum corneum is to prevent the skin dehydrating. This is achieved by the natural moisturising factor (NMF), which is a collection of water soluble substances that absorb water from the air and combine it with their own water content. This allows the stratum corneum to keep hydrated despite exposure to the environment.

Lipids (ceramides, cholesterol, fatty acids and sebum) also help control water loss and prevent entry of water-soluble agents and harmful bacteria by providing a waterproofing layer on the skin’s surface. Lipids also keep the skin supple, preventing it from cracking and breaking, which would allow pathogens to enter into the skin and could cause an infection.

Dermis

• The dermis is the layer of skin that lies below the epidermis. It is a 3-5mm thick layer of extra-cellular tissue. The dermis has a high water content. It contains most of the living structures of the skin including blood vessels, sweat glands and sebaceous glands.

The main functions of the dermis are:

• To provide strength and flexibility

• To provide a system of capillaries to nourish the cells of the lower layers of the epidermis and to remove waste products

• To control temperature and blood pressure.

The dermis has two layers:

• Papillary layer

• Reticular layer

Papillary layer

• This is composed of loose connective tissue. The surface of the papillary layer is covered with tiny, irregularly shaped projections called dermal papillae.

• These fit into the underside of the epidermis forming a secure bond (eg like Velcro). They contain intricate networks of blood and lymphatic capillaries and nerve endings. These networks nourish the lower layers of the epidermis and hair follicles, carry oxygen to the tissues and remove waste from the tissues.

Reticular layer

• This is made up of thick tough fibrous connective tissue which helps to hold and support the dermis. It connects the dermis to the hypodermis.

Cells of the dermis

• The main cells of the dermis are fibroblasts, mast cells and phagocytic cells.

Fibroblasts/fibre cells

• fibroblasts are important for tissue repair following tissue damage.

Fibroblasts produce two important proteins – collagen and elastin.

The production of collagen and elastin slows down as we age causing wrinkles and a loss of skin tone.

Collagen – fibres provide strength and elasticity.

Elastin – holds collagen in place and forms an organised network of elastic fibre cells in the dermis

Collagen

Collagen – fibres provide strength and elasticity.

These wavy white fibres form a network and hold bodily tissues, such a skin, bone and muscles together. The wave allows the fibres’ length to be extended, and the fibres to run in a specific direction, following the contours of the body.

Collagen makes up 75 per cent of the skin’s weight.

Elastin

• Elastin – holds collagen in place and forms an organised network of elastic fibre cells in the dermis.

Elastin is a very stretchy yellow fibre. Just like and elastic band, elastin can stretch and return back to its original shape.

However, if the skin is overstretched the elastin fibres will break, causing stretch marks. Elastin accounts for 5 per cent of the body’s weight.

Mast cells

• mast cells release histamine in response to damage to local tissues caused by micro-organisms.

• Histamine causes the blood vessels to leak so that the immune system has better access to the damaged tissues and can fight the micro-organisms. White blood cells are also attracted to histamine, drawing them to the damaged tissue.

• Phagocytic cells - are white blood cells which move through the skin’s tissues destroying pathogens and other cell debris.

• Hyaluronic acid – Hyaluronic acid is a naturally occurring substance found in the extracellular matrix of the dermis. This helps keep the skin hydrated. It is able to attract and hold water up to 1000 times its weight. It plays a crucial role in skin repair, supporting the formation of collagen and elastin. As we age, the skin produces less hyaluronic acid, especially after 50, and contributes to the appearance of ageing on the skin.

Sensory nerve endings

• The skin is packed with sensory nerve endings which relay information about tactile sensation to the brain. Different nerve receptors respond to different sensations.

Blood vessels

• The dermis contains a rich, delicate network of blood vessels. The small blood vessels in the outer areas of the skin are known as the micro-circulation and are prone to vasodilation and vasoconstriction. The circulation of blood brings oxygen and nutrients to the dermis, the hair follicle and the epidermis and removes the waste products made during cellular activity.

Lymphatic vessels

A network of lymph capillaries nourish the cells in the dermis. These vessels allow lymphatic fluid to leave and bathe the cells in the extracellular tissue fluid. Tissue fluid moves back into the lymph vessels to remove waste from the tissues.

Sweat glands (sudoriferous glands)

• The two main purposes of sweat glands are:

1 to help regulate the temperature of the body

2 to help eliminate waste.

Sweat cools down the body by removing heat from the skin’s surface. It helps to maintain hydration of the skin’s surface. Sweat is excreted as a clear watery fluid. It takes away waste substances, eg water, sodium and potassium chloride (salts), ammonia and urea. There are two types of sweat glands:

1 apocrine glands

2 eccrine glands

Apocrine and eccrine glands

• Apocrine glands – are found under the arms and around the groin. Most apocrine glands open into hair follicles.

• Eccrine glands – are found all over the body. Eccrine sweat is formed when sodium is secreted into the base of a sweat gland. The sodium attracts water from the surrounding tissues and is excreted onto the surface of the skin. Sweat from eccrine glands also contains urea.

Sebaceous glands

• Sebaceous glands can be found all over the skin, except on the palms of the hands and soles of the feet. Most sebaceous glands open into hair follicles where they secrete sebum but some open directly onto the skin.

Sebaceous glands produce sebum (a lipid). Sebum is the skin’s natural emollient and prevents the skin form drying out. It forms a barrier to keep moisture in.

sebum helps prevent the growth of bacteria as long as the sebum does not become excessive. Too much sebum will cause the skin to become oily and look shiny particularly around the nose, chin and forehead. Very oily skin attracts surface dirt and the pores might become blocked causing comedones, papules and pustules can occur. The size and quantity of sebaceous glands differs between ethnic groups.

Hair follicle

• The hair follicle is a complex structure that produces hair. It extends deep into the dermis.

Arrector pili muscle

These are tiny muscle fibres that are attached to the hair follicle. When they contract, they pull the hair up away from the skin. It is the action of these muscles that gives us a ‘goose flesh’ appearance when we are cold or frightened. The hairs, when raised, trap air holding warmth to the skin.

Subcutaneous (hypodermis layer)

• This forms a link between the underlying structures and the skin. It is made up of a layer of subcutaneous fat cells which provide some cushioning and protection from external pressures and some thermal insulation. It varies in thickness depending on the sex of an individual and area of the body.

Functions of the skin

The skin has seven functions:

• sensation

• temperature regulation

• absorption

• protection

• excretion

• secretion

• production of Vitamin D.

Sensation

The skin contains approximately five million tiny sensory cells. These sensory cells enable us to respond to sensations that are applied to the surface of the skin (such as touch, pressure and vibrations). The cells respond to environmental changes and send information to the brain where the sensation is felt. Sensory nerve endings are located mainly in the dermis but some free nerves end in the epidermis.

Temperature (heat) regulation

The body needs to be maintained at a constant temperature of about 36.8°C to function correctly.

The skin responds to an increase in temperature by dilating the blood vessels in the dermis (vasodilation) to radiate heat away from the body where it is open to the elements. The skin begins to sweat. As the sweat evaporates, it takes the heat away from the skin’s surface, allowing the body to cool.

If the body gets too cold, the blood vessels constrict (vasoconstriction) to keep heat nearer to the essential organs of the body. Shivering makes the muscle contract. This muscle contraction produces energy to keep warm. Heat loss from the skin is affected by the environment and the amount and type of clothing worn.

Absorption

The skin is not completely waterproof. It allows certain substances (such

as hormones) to be absorbed only in a limited capacity. Some examples

of substances that can be absorbed are nicotine, hormones and steroids.

Substances that can enter the skin are absorbed:

• between the cells of the epidermis

• through sweat glands

• through a hair shaft.

Protection

The skin forms a water-resistant seal over the body. It is very hardwearing and acts as a defence against chemicals, micro-organisms, dehydration and damage. Sebum, water and other substances are secreted onto the skin’s surface to keep it waterproof, supple and flexible.

The surface of skin is slightly acidic (pH 4.5–5.5), which prevents harmful bacteria growing. Melanin acts as a chemical filter, absorbing and reflecting UV radiation.

The hypodermis cushions the underlying bones and organs to help prevent damage from external forces and pressure. The hypodermis and dermis together protect the body against temperature changes.

Excretion

Excretion is the process that our bodies use to get rid of waste or unwanted substances. The skin is a minor excretory organ. It excretes sweat, which contains water, sodium and potassium chlorides (salts),urea and uric acids which gives the body its personal odour. If we don’t wash our skin or clothes regularly, bacteria break down our sweat, causing unpleasant odours.

Secretion

Secretion is the process that our bodies use to release substances needed

by the body. Sebum is secreted into the hair follicles and onto the skin.

Sebum is an oily substance that keeps the hair and skin soft, supple and

flexible. It can also give the skin and hair a shiny appearance. Sebum

contains antibacterial substances to prevent the growth of harmful

micro-organisms on the skin’s surface.

Synthesis of Vitamin D

Vitamin D is synthesised in the skin as a response to exposure to ultraviolet B radiation (UVB). Cholecalciferol is produced when the sun penetrates the skin. Cholecalciferol is taken to the liver where it is made into calcidol and stored as Vitamin D.

If you block UVB, you will prevent the production of Vitamin D. Dark skin needs more exposure to UVB to produce the same amount of Vitamin D than light skin, as melanin restricts absorption of the UVB rays.

Skin repair and scar tissue

Although the body is able to repair tissue damage there is always some scar tissue.

When the skin is broken, blood cells move into the wound and the blood clotting process starts. A protein in the blood plasma called fibrinogen is released and this starts to form a mesh over the surface. This mesh prevents further blood leaking out. The mesh dries out to from a scab.

Skin repair and scar tissue

Histamine is released to make the blood vessels dilate. Vasodilation allows blood cells to leak out from the blood vessels to help in the healing process. The cells can also attack unwanted micro-organisms that might have entered through the open wound. The increased circulation gives the area an inflamed red appearance.

Skin repair and scar tissue

Fibroblast cells begin to produce new collagen cells, and a protein called actin. Actin helps to slowly draw the edges of the wound together as it is able to contract. It takes the epidermis about 48 hours to heal but the deeper tissues take much longer, and the area might look red for 2-4 weeks. Some very deep damage might take even longer to fully repair. Working over scar tissue is contra-indicated as the healing process could be on=going even though the epidermis has healed.

The growth cycle of the skin

Skin production is a continuous process that occurs in the germinativum layer of the epidermis where new cells are reproduced by mitosis. In the skin, new cells mature as they migrate through the stratum germinativum and stratum spinosum. At this stage the cells start to become keratinised, a process which gradually causes cell death. By the time the cells reach the top of the stratum granulosum they are dead and continue to be pushed upwards, as new cells are produced in the lower layers of the epidermis. In the stratum corneum the corneoctyes are naturally desquamated, removing them from the skin’s surface. In young adults with healthy skin this process takes approximately 21 days. This time gradually increases as we age.

explain how natural ageing, lifestyle and environmental factors affect the condition of the skin and muscle tone

The effects of ageing on the skin

Ageing is dependent on a variety of factors which include internal and external influences. Some ethnic groups have a slower ageing process than others.

The large amount of collagen in Afro-Caribbean skin prevents some of the effects of ageing. Caucasian (white) skin tends to be thinner and more prone to damage by the sun and the environment.

Factors that affect the skin

There are internal and external factors that affect the health and appearance of the skin.

Internal factors

External factors

External factors

Describe diseases and disorders of the skin

Bacterial infections

Our body is covered with millions of tiny bacteria. Bacterial can be good as well as bad. Some bacterial infections are very contagious, and you should not feel under pressure to treat any infected area.

bacterial infections

• impetigo

• conjunctivitis

• hordeolum – stye

• furuncles – boils

• Carbuncles

• Paronychia – tissue surrounding nails

viral infections

viral infections are very contagious and you should not feel under pressure to treat anyone you feel is unwell or treat any area that has signs of a viral infection.

• herpes simplex

• herpes zoster - shingles

• Verrucae, warts

Infestations

Most infestations are conditions that you are unlikely to come across in the salon but it is still important that you are familiar with the conditions and are able to recognise them. It is always a possibility that you might be exposed to them

• scabies - itch mites

• pediculosis capitis - head lice

• pediculosis corporis

fungal diseases

You should be able to recognise tinea pedis (athlete’s foot). It is one of

the most common conditions that clients will present to you.

• tinea corporis – body ringworm

• tinea pedis – athlete’s foot

sebaceous gland disorders

Some of the most common skin disorders and diseases that a therapist will come into contact with will be linked to the sebaceous glands. These glands are very reactive during hormonal changes particularly during puberty. These conditions are often easily irritated by the use of incorrect products and skincare. It is important to treat the skin gently and not remove all the natural oils that the skin needs for protection.

pigmentation disorders

It is important to be able to recognise common skin pathologies (diseases and disorders) to know whether or not treatments should be carried out. In some cases, treatments may be carried out but will require modification.

There are several common disorders that relate to pigment changes in the skin. Skin pigment can be lost, causing hypo-pigmentation, and pigmentation can be increased, causing hyperpigmentation. In many cases the changes cannot be reversed. Avoiding sun exposure (UVA and B) will help where pigmentation has been increased. It takes a long time for pigmentation to even out and most clients will not be able to realistically

keep affected areas out of the sun completely so that the skin has a chance to recover.

skin disorders involving abnormal growth

Therapists commonly see abnormal skin growths (from thickening of the skin on the soles of the feet to abnormal skin tags) that are a nuisance to the client. A therapist is unable to improve these disorders directly.

• psoriasis

• seborrheic or senile warts

• malignant tumours

Skin disorders involving allergies and irritants

Allergies and irritation are common in the salon. There is always the risk that a client might have a reaction to a product and therapists need to be aware of what to look for. Maintaining good hygiene practice can lead to sensitive skin. Work-related dermatitis is a now a condition that needs to be reported.