Copyright EMAP Publishing 2017 This article is not for distribution

Nursing Practice Keywords Collagen/Melanin/Reactive oxygen species/Dry skin/Pressure Systems of life This article has been The skin double-blind peer reviewed In this article... ● Age-related changes in the epidermis, dermis and hypodermis ● Features of older skin and skin conditions that are common in old age ● Considerations for skin assessment and skin care in older people

Anatomy and physiology of ageing 11: the skin

Key points Author Yamni Nigam is associate professor in biomedical science; John Knight is Skin ages senior lecturer in biomedical science; both at the College of Human Health and chronologically from Science, Swansea University. within (intrinsically) and due to external Abstract The skin, the largest organ in the human body, performs important functions factors such as such as thermoregulation, storage and synthesis, sensation and protection. With exposure to advancing age, these functions are increasingly impaired. Changes occur in the ultraviolet radiation epidermis, dermis and hypodermis leading to thin, dry and sagging skin, while loss of (extrinsically) structure and integrity diminishes the skin’s ability to protect the body and detect changes in temperature and pressure. Ageing skin is more prone to infection, trauma, Skin ageing is partly tears and pressure ulcers. This is the last article in our series on the anatomy and caused by potent physiology of ageing. molecules and reactive oxygen Citation Nigam Y, Knight J (2017) Anatomy and physiology of ageing 11: the skin. species, resulting in Nursing Times [online]; 113: 12, 51-55. oxidative stress and damage to cells he fact that it covers the entire The second layer or dermis, the thickest With age, skin body means the skin is the most layer of skin, contains cells that give skin its becomes slack obvious place to observe signs of strength, support and flexibility. Sensory and rough, readily Tageing. The skin is the body’s receptors in the dermis allow the body to forming lines largest organ – an average adult’s skin has experience pressure, pain and temperature, and wrinkles a surface area of approximately 1.67m2 and while small blood vessels provide the skin weighs around 4-5kg (Marieb and Hoehn, with nutrients and remove its waste prod- Aged skin is more 2015). Skin is a malleable but tough struc- ucts. Sebaceous glands – present all over the fragile, thin over ture, serving as a bag holding in all the body except on the palms of the hands and bony areas, and body’s contents; without it, we would the soles of the feet – produce oil that keeps more prone to quickly succumb to water and heat loss, the skin hydrated, softens hair and helps trauma and tears, and pathogen invasion. kill bacteria in the pores. The dermis also infection and hosts the sweat glands and hair follicles. pressure ulcers than Skin structure Below these two main layers is an inner- younger skin The skin consists of two main parts: the most layer of subcutaneous tissue, the epidermis and the dermis. The epidermis hypodermis. This anchors the skin to the In older people, is the outside layer and protects the under- fascia (the underlying connective tissues atrophy of the lying layers from the environment. It hosts that wrap around skeletal muscles) and is dermis means cells that produce keratin, a substance that therefore known as the superficial fascia. wound-healing makes the skin waterproof and stronger, The hypodermis consists mainly of fat ability diminishes and cells that contain melanin, a photo- cells that insulate the body and helps it to protective pigment that gives skin its conserve heat. colour. Although there is no blood supply in the epidermis, there are cells that afford Skin function the body immunity against bacteria and The skin and its derivatives (sweat glands, other invading organisms hair and nails) perform important func-

Nursing Times [online] December 2017 / Vol 113 Issue 12 51 www.nursingtimes.net Copyright EMAP Publishing 2017 This article is not for distribution Nursing Practice Systems of life tions such as: Box 1. Reactive oxygen Extrinsically aged skin is characterised l Thermoregulation; species by coarse and deep wrinkling, rough tex- l Storage and synthesis; ture, telangiectasia (spider veins), irregular l Sensation; l Reactive oxygen species (ROS) are or mottled pigmentation, a sallow or yellow l Protection. molecules generated by the skin complexion and a loss of elasticity (Tobin, during normal cellular metabolism 2017). The severity of extrinsic ageing Thermoregulation that destroy skin cell membranes, depends on skin type – fairer skin is Blood flow in the dermis helps the body DNA and enzymes affected more than darker skin. adjust to cold and heat. Sweat glands pro- l ROS cause the activation of duce about 500ml of sweat a day, providing collagenases and enzymes that The ageing epidermis an important cooling mechanism. In hot degrade collagen as well as other The epidermis is formed of protective kerati- weather, the nervous system stimulates proteins that make up the nised squamous epithelial tissue, with an the dermal blood vessels to dilate and extracellular matrix, thereby outer barrier of dead cells (stratum cor- sweat glands can increase their production impairing the structural integrity neum). Underneath are several layers of epi- to up to 12L a day (Marieb and Hoehn, of the skin dermal cells, ending in a basal layer of rap- 2015). The evaporation of sweat cools the l With advancing age, the number of idly dividing cells located next to the body and prevents it from overheating. ROS increases and the ability of the basement membrane and dermis. Keratino- In cold weather, the dermal blood ves- body’s antioxidant defence system to cytes (cells producing keratin) and melano- sels constrict, warm blood flow bypasses get rid of them declines cytes (cells producing melanin) are found in the skin, the skin cools down further and the epidermis. Also present are Langerhans this slows down heat loss from the body. cells, dendritic cells that guard the ‘front fibroblasts and collagen production, and a door’ of the immune system, preventing Storage and synthesis flattening of the junction between the epi- unwanted foreign micro-organisms from The skin acts as a storage facility for lipids dermis and dermis. Intrinsically aged skin entering the body via the skin. With age, and water. When it is hit by sunlight, mod- is unblemished, smooth, pale, dry and less there is a substantial loss of melanocytes and ified cholesterol molecules are converted elastic with fine wrinkles (Landau, 2007). Langerhans cells (Yaar and Gilchrest, 2003). to a vitamin D precursor, which is trans- Extrinsic skin ageing is caused by envi- Having no blood supply, the epidermis ported to other body areas to be made into ronmental factors such as: gains its nutrition through contact with vitamin D (essential for calcium absorp- l Smoking; the dermis. A major cutaneous change in tion from the gut). Skin cells also make col- l Diet; intrinsic skin ageing is a reduction in the lagenases; these are enzymes that support l Exposure to chemicals; surface contact between the epidermis and the natural turnover of collagen. l Trauma; dermis. There is a loss of rete ridges (epi- l Exposure to UV radiation thelial extensions that project into the Sensation (photoageing). underlying connective tissue), which nega- The skin has a variety of nerve endings that Such factors have been shown to stimu- tively affects the capillary-rich dermal feel touch, pressure, vibration, warmth, late the production of ROS and generate papillae, resulting in a reduced supply of cold and pain, allowing the body to receive oxidative stress (Valacchi et al, 2012). nutrients, metabolites and oxygen to the sensory stimulation from the surrounding The greatest source of extrinsic ageing epidermis (Tobin, 2017). The reduced con- environment. is accumulated, unprotected exposure to tact between dermis and epidermis also UV radiation; over 80% of facial skin results in less resistance to shearing forces. Protection ageing is due to low-grade chronic UV In addition, with age, the epidermis atro- With its stratum corneum (multiple layers exposure (Flament et al, 2013). Actinic phies because we produce fewer cells – cell of dead, flat cells and glycolipids) and hard exposure affects the epidermis, causing production decreases by up to 50% between keratinised cells, the skin forms a contin- irreparable damage to cellular DNA, and our 20s and our 70s (Cerimele et al, 1990). uous physical barrier. It also provides induces the generation of ROS. Less than The stratum corneum has a barrier chemical barriers: 30 minutes after UV irradiation, the function and keeps the skin from drying l Acid secretions inhibiting bacterial amount of hydrogen peroxide – a potent out; although it does not become thinner growth; ROS – has been shown to more than double with age, it is not replaced as quickly, so l Dermcidin in sweat; in human skin (Rigel et al, 2004). UV expo- skin is increasingly rough and dry. Extreme l Bactericidal substances in sebum; sure also disrupts collagen synthesis, skin dryness (xerosis) can be seen in ageing l Melanin preventing ultraviolet damage leading to acute collagen loss (Rinner- skin, and this brings about an increased (Marieb and Hoehn, 2015). thaler et al, 2015). susceptibility to irritant dermatitis (Tobin, Exposure to UV radiation increases skin 2017). As mitosis in the basal layer of the Intrinsic and extrinsic skin ageing pigmentation and stimulates melanocyte epidermis is slowed down, healing takes Skin ages intrinsically (chronologically proliferation. Melanin helps protect more time. from within) and extrinsically (due to against the cumulative damaging effects With advancing age, there is a reduc- external factors). Intrinsic skin ageing of UV radiation, which explains why the tion in the hormones and chemical signals results from the passage of time and is rates of skin cancer are much higher in that are important for skin growth and mainly due to the action of reactive oxygen Caucasians than in black people and why repair, as well as a decline in the receptors species (ROS) (Box 1) (Naidoo and Birch- basal cell carcinomas occur almost exclu- that detect them; as an example, the Machin, 2017). It occurs within the skin sively in the sun-exposed skin of light- number of vitamin D receptors in epi- itself due to reductions in dermal mast cells, skinned people (Tobin, 2017). dermal keratinocytes declines with age.

Nursing Times [online] December 2017 / Vol 113 Issue 12 52 www.nursingtimes.net Copyright EMAP Publishing 2017 This article is not for distribution Nursing Practice Systems of life

Fig 1. Age-related changes in the epidermis and dermis Dry epidermis • Reduction in sebaceous and sweat glands activity Thin epidermis • Slower repair function Fewer melanocytes • Decreased vitamin D • Paler skin production • Reduced tolerance • Reduced number of to sun exposure Langerhans cells

Thin dermis • Sagging and wrinkling due to Fewer active follicles collagen fibre loss • Thinner, sparse hair

Reduced sweat gland activity • Tendency to overheat Changes in distribution of fat and hair • Due to reductions in sex hormone levels Reduced blood supply • Slower healing • Reduced ability to lose heat

The ageing dermis to regain its shape after deformation Fig 1 illustrates some of the age-related The dermis contains blood capillaries that (Graham-Brown, 2004). changes happening in the epidermis and are important for providing oxygen and Fibroblast activity decreases with age: dermis. nourishment to all skin cells. It comprises these cells shrivel and have fewer epi- an extracellular matrix containing a sturdy dermal growth factor receptors. There is The ageing hypodermis mesh of collagen and elastin fibres, which an associated drop in collagen synthesis, The hypodermis consists mainly of fat, give the skin its strength, elasticity and an atrophy of collagen bundles and an and acts as an insulator and shock resilience. Key cells in the dermis are: increase in the levels of metalloproteinases absorber. With age, there is a loss of subcu- l Fibroblasts – these synthesise collagen, and enzymes that degrade collagen. As a taneous fat and the skin becomes thinner elastin and the other structural consequence, collagen is of poor quality and less resistant to trauma. The reduced molecules of the matrix; and wound healing is impaired. volume of subcutaneous fat means the role l Mast cells – these are immune cells that As collagen fibres decrease in number, of the hypodermis in limiting conductive produce histamine. rupture, cross-link and stiffen, their heat loss is impaired. The distribution of With increasing age, there is a loss of capacity to bind water diminishes and the subcutaneous fat changes too: it decreases dermal volume, and dermal thickness skin loses elasticity and becomes wrinkled. in parts of the face and hands but increases decreases by about 20%. There is a 50% Wrinkles appear to be due not so much to in the thighs and abdomen. The reduction decrease in the number of mast cells and a the degeneration of elastin fibres, as previ- of fat over bony areas increases the risk of 60% decrease in blood flow (Farage et al, ously thought, but to a decreased water- pressure ulcers (Box 2) and fractures. 2013); as a result, the skin’s response to holding power of collagen and mucopoly- injury or infection is compromised. saccharides (Richards and Edwards, 2014). Loss of protective function Collagen is the body’s most abundant Skin ageing is associated with a The skin protects the body against protein, conferring strength and support decrease in cutaneous perfusion and mechanical injuries, mainly due to its to the skin. The collagen content of reduced vascularity, mainly in the superfi- ability to undergo reversible deformation the dermis decreases by 1% per year cial (papillary) part of the dermis. There is when influenced by external forces – for throughout adult life (Rigel et al, 2004). a drastic reduction in the number of example, weight. Human skin can be In addition, collagen itself changes dermal blood vessels accompanied by a stretched to several times its original size. from well-organised bundles of fibres shortening of capillary loops in the dermal If, on termination of the external force, the in young skin to fragmented and dis- papillae. This results in skin pallor, skin returns to its initial shape, it is con- organised fibres in older skin; it also loses depleted nutrient exchange and impaired sidered perfectly elastic; failure to do this its interwoven extensions with elastin thermoregulation (Baumann, 2007; Waller is known as residual deformation. The skin

PETER LAMB PETER fibres, which in youth enable the skin and Maibach, 2005). of children is better able to withstand load

Nursing Times [online] December 2017 / Vol 113 Issue 12 53 www.nursingtimes.net Copyright EMAP Publishing 2017 This article is not for distribution Nursing Practice Systems of life and tension, and is more elastic than that Box 2. Pressure ulcers round-to-oval, bright red, dome-shaped of older people (Vogel, 1987). With age, papules and pinpoint macules, most com- skin becomes stiffer, thinner, less tense l Pressure ulcers are a particular risk in monly on the trunk or proximal extremi- and less flexible (Pawlaczyk et al, 2013). older people with compromised ties. Initially described by Campbell de In addition, there is a loss of sensory blood circulation, reduced mobility or Morgan in 1872, a cherry angioma is formed receptors that enable the body to feel pres- faecal and/or urinary incontinence by numerous newly developed capillaries sure, pain and temperature (Pacinian and l Most pressure ulcers will harbour a and prominent endothelial cells arranged Meissner’s corpuscles), as well as a loss of bacteraemia and this can be the in a lobular fashion in the papillary dermis sensory nerve endings in the epidermis cause of localised infection, cellulitis (Kim et al, 2009). Early lesions appear as and dermis. This makes older people less or osteomyelitis flat, red macules that look like petechiae. able to detect changes in the environment l Pressure ulcers, which are As they develop, they become 1-5mm red and, therefore, more prone to injury. preventable, can cause great pain, papules. Cherry angiomas are usually Sebaceous glands produce less sebum, distress and even death; sepsis is a asymptomatic but may bleed with trauma. so the protection against infection very serious complication afforded by the acidity of sebum is Senile purpura reduced. This makes the skin less able to Senile purpura is a common, benign and resist disease and skin infections, which is maintain the production of melanocytes self-resolving condition affecting more why older people have an increased sus- (Nishimura et al, 2005). Wood et al (2009) than 10% of people aged over 50 years. It is ceptibility to skin infections. The types of have shown that hydrogen peroxide, characterised by the recurrent formation organisms that cause primary skin and which is produced by hair follicles, builds of irregularly shaped, dark purple ecchy- soft tissue infections are diverse, and up over time and leads to a gradual loss of moses, about 1-4cm in diameter, often include bacterial (cellulitis), viral (shin- hair colour. Greying occurs at different appearing on the forearms after a minor gles) and fungal (thrush) pathogens. rates in different hair follicles, either rap- trauma (Trozak et al, 2006). They do not idly or slowly over decades. White hair is undergo the colour changes of a normal Features of aged skin thicker and grows faster than pigmented bruise and take up to three weeks to Wrinkles and sagging hair (Trueb and Tobin, 2010). resolve. Risk factors include chronic sun- Several factors contribute to the formation As we age, nail growth starts to slow light exposure and the use of oral or topical of wrinkles: gravitational force, loss of down. Nails become more brittle and corticosteroids and anticoagulants. subcutaneous fat and repeated traction develop beaded ridges due to a reduction Senile purpura is caused by the thin- exerted by facial muscles over expression in lipophilic sterols and fatty acids (Helm- ning of dermal tissues and increase in the lines, which results in deep creases over dach et al, 2000) (Box 3). fragility of blood vessels. As a result, the forehead, between the eyebrows, peri- superficial vessels tear and rupture, even orbitally and in the nasolabial folds. Clin- Skin lesions with negligible trauma. The subsequent ical manifestations include dryness, laxity The number of melanocytes decreases leakage of blood into the surrounding and slackness; these are most easily with age and those remaining increase in dermis results in senile purpura. observed on the face, which is the most size; this explains why blotchy pigmented exposed area of skin. In addition, facial ‘liver spots’ may appear on the back of the Assessment and care muscles show an accumulation of the ‘age hands. The formation of benign skin Although age-related skin problems are pigment’ lipofuscin, a marker of muscle lesions such as seborrheic keratoses or not usually life threatening, they can cause cell damage. This damage, along with solar lentigos (‘age spots’) typically starts distress and decrease quality of life. Skin diminished neuromuscular control, con- between the third and fifth decade of life, conditions that commonly affect older tributes to wrinkle formation. and speeds up thereafter. Due to the cumu- people are eczema, psoriasis, infections Depletion and redistribution of facial lative effects of chronic sun exposure, the and pruritus (Davies, 2008), many of fat (which tends to accumulate in pockets risk of skin cancers also increases with age. which are associated with dry skin and such as the nasolabial folds and subman- Cherry angiomas are cutaneous vas- itching. Decreased sebaceous secretions, dibular region) as well as gravity contribute cular proliferations commonly seen in loss of oil glands and circulatory changes to the loosening and sagging of the skin. older people, and typically appear as contribute to dry and scaly skin in the

Changes in hair and nails Box 3. Ageing nails Chest, axillary and pubic hair all decrease in density with age, but men may experi- l Ageing results in thickening of the nails, particularly the toenails ence increased hair growth in other body l Thick, hard nails become difficult to cut and older people may not have the sites like the eyebrows, ears and nostrils strength required to do so (Tobin, 2017). Hair becomes drier because l If nails overgrow, because they are confined in shoes, they may begin to curl under sebaceous glands produce less sebum. the toes; this results in a condition called ram’s horn nails, in which the nail curls Hair greying, which is genetically con- over the top of the toe and grows into the flesh on the bottom, causing pain trolled, appears to be a consequence of a l Fungal infections become increasingly common in old age, causing thick, brittle, depletion of hair melanocytes, which can misshapen and discolored nails; they are more likely in people who have underlying no longer provide colour to the developing conditions such as diabetes hair in the follicle. This depletion may l If in severe discomfort due to nail problems, older people may avoid walking, occur as a result of signal failing by mel- thereby becoming less mobile anocyte stem cells, which can no longer

Nursing Times [online] December 2017 / Vol 113 Issue 12 54 www.nursingtimes.net Copyright EMAP Publishing 2017 This article is not for distribution Nursing Practice For more articles on older people, go to Systems of life nursingtimes.net/olderpeople

person’s risk of infection. Skin tears, abra- Current Problems in Dermatology; 35: 1-13. sions, lacerations and ulcers are often Marieb EN, Hoehn KN (2015) Human Anatomy and Physiology. Upper Saddle River, NJ: Pearson. caused by friction, shearing force, pres- Naidoo K, Birch-Machin MA (2017) Oxidative sure or moisture. Simple manoeuvres, stress and ageing: the influence of environmental such as sliding patients across bed sheets pollution, sunlight and diet on skin. Cosmetics; or removing tape from skin, may result in 4: 1, 4. significant skin trauma. Nishimura EK et al (2005) Mechanisms of hair graying: incomplete melanocyte stem cell As skin ages, it becomes thinner, more maintenance in the niche. Science; 307: 5710, transparent and more easily bruised. Med- 720-724. ications such as corticosteroids can make Patel T, Yosipovitch G (2010) The management of the skin even more fragile. It is therefore chronic pruritus in the elderly. Skin Therapy Letter; 15: 8, 5-9. particularly important to avoid applying Pawlaczyk M et al (2013) Age-dependent tape (other than soft silicone tape) to hold biomechanical properties of the skin. Advances in dressings in place. Alternatives such as Dermatology and Allergology; 30: 5, 302-306. lightweight elasticated tubular bandages Richards A, Edwards S (2014) Essential should be used to hold dressings in place Pathophysiology for Nursing and Healthcare Students. Maidenhead: Open University Press. on the arms and legs. If hydrocolloid dress- Rigel DS et al (2004) Photoaging. Boca Raton, FL: ings are used, they should be removed CRC Press. with great care to avoid damaging the skin. Rinnerthaler M et al (2015) Oxidative stress in In older people, the wound-healing aging human skin. Biomolecules; 5: 2, 545-589. Scheinfeld N (2005) Infections in the elderly. ability of the skin diminishes and the Dermatology Online Journal; 11: 3, 8. Emollients increase the amount water held immune system functions less vigorously. Tobin DJ (2017) Introduction to skin aging. Journal in the skin and so are useful for older people Older people are more prone to mal- of Tissue Viability; 26: 1, 37-46. nutrition and obesity, factors that facili- Trozak DJ, Tennenhouse DJ (2006) Dermatology lower extremities, and skin becomes more tate the entry of pathogens into the skin, Skills for Primary Care: An Illustrated Guide. Totowa, NJ: Humana Press. susceptible to inflammation, infection hypertension and conditions such as Trüeb RM, Tobin DJ (2010) Aging Hair. Berlin: and rashes. diabetes, which decrease blood flow and Springer Verlag. Skin assessment and skin care are delay healing. Vogel HG (1987) Age dependence of mechanical essential components of nursing care for Often presentation of skin infection is and biochemical properties of human skin. Part I: stress-strain experiments, skin thickness and older people. Skin assessment should be initially non-specific, with acute disorien- biochemical analysis. Bioengineering and the Skin; undertaken regularly and encompass tation, anorexia or weakness, and fever 3: 67-91. detailed visual inspection and assessment does not always occur (Scheinfeld, 2005). Waller JM, Maibach HI (2005) Age and skin of texture, moisture, turgor and tempera- These factors make it imperative that older structure and function, a quantitative approach (I): ture; personal skin hygiene should be patients are carefully monitored and blood flow, pH, thickness, and ultrasound echogenicity. Skin Research and Technology; 11: 4, encouraged (Cowdell and Radley, 2012). receive early and correct treatment; for 221-235. Skin care should include the care of nails. example, antibiotics or antiviral drugs Wood JM et al (2009) Senile hair graying: Pruritus, a common complaint in older should be started as soon as possible to H2O2-mediated oxidative stress affects human adults, may be caused by dryness, reduce symptoms and shorten the dura- hair color by blunting methionine sulfoxide repair. FASEB Journal; 23: 7, 2065-2075. NT irritation or infection. It is also linked to tion of infection (Laube, 2004). Yaar M, Gilchrest BA (2003) Aging of skin. In: diabetes, kidney disease and anaemia. Freedberg IM et al (eds) Fitzpatrick’s Dermatology About 85% of older people develop ‘winter References in General Medicine. New York: McGraw-Hill. Baumann L (2007) Skin ageing and its treatment. itch’, as dry, overheated indoor air com- Journal of Pathology; 211: 2, 241-251. pounds skin dryness. Pruritis can substan- Cerimele D et al (1990) Physiological changes in For more on this topic go online... tially decrease quality of life, especially if ageing skin. British Journal of Dermatology; 122 l  it leads to sleep deprivation (Patel and (Suppl 35): 13-20. Maintaining skin health in older Cowdell F, Radley K (2012) Maintaining skin health people Yosipovitch, 2010). in older people. Nursing Times; 108: 49, 16-20. Bit.ly/NTSkinHealth Emollients have a crucial role to play in Davies A (2008) Management of dry skin skin health, especially for older people conditions in older people. British Journal of who have dry and itchy skin; these increase Community Nursing; 13: 6, 250-257. Farage MA et al (2013) Characteristics of the aging Anatomy and physiology of the amount of water held in the stratum skin. Advances in Wound Care; 2: 1, 5-10. ageing – updated series corneum, either by drawing it from the Flament F et al (2013) Effect of the sun on visible Article Date dermis or by trapping it and preventing its clinical signs of aging in Caucasian skin. Clinical, Cosmetic and Investigational Dermatology; 6: Part 1: the cardiovascular system Feb evaporation. Many emollients – prescribed 221-232. Part 2: the respiratory system Mar as ointments, creams, lotions or sprays – Graham-Brown RAC (2008) The ages of man and Part 3: the digestive system Apr effectively alleviate skin dryness. They are their dermatoses. In: Burns T et al (eds) Rocks Part 4: the renal system May textbook of Dermatology, 7th edn. Oxford: often used alongside other treatments, Part 5: the nervous system Jun Blackwell Science such as steroids, for conditions like psori- Helmdach M et al (2000) Age and sex variation in Part 6: the eyes and ears Jul asis or eczema. lipid composition of human fingernail plates. Skin Part 7: the endocrine system Aug Well-nourished and UV-protected skin Pharmacology and Applied Skin Physiology; 13: 2, Part 8: the reproductive system Sep exhibits remarkable resilience to intrinsic 111-119. Part 9: the immune system Oct Kim J-H et al (2009) Cherry angiomas on the Part 10: the musculoskeletal system Nov ageing (Tobin, 2017). However, any breach scalp. Case Reports in Dermatology; 1: 1, 82-86. Part 11: the skin Dec in tissue integrity may increase the older Landau M (2007) Exogenous factors in skin aging.

Nursing Times [online] December 2017 / Vol 113 Issue 12 55 www.nursingtimes.net