Anatomy of the skin

Aims and objectives

• To understand the underlying structures of the skin

• To gain a basic understanding of the process of wound healing.

• To be able to identify different tissue types in areas such as the wound bed, wound edge and surrounding skin

Anatomy of the skin

Is it important to know the Structure and functions of the

skin?

• How many layers does the skin consist of?

• Largest and most visible organ• Made up of two main layers: Epidermis – very thin layer and is

firmly attached to the dermis at the dermo- epidermal junction.

Dermis- made up of two layers comprising of fibrous proteins, collagen and elastin which give skin its strength and elasticity.

Below dermis is subcutaneous layer , this provides support to the dermis and stores fat which protects the internal structures.

• Does the skin vary in depth?

• Thinnest over eyelids -O.1mm • Thickest over palms and soles of the feet –

1mmThe skin is the largest organ of the body it weighs between 6-8 1bsIt has a surface area of 20 square feet.

What are the functions of the skin?

• Protection of internal structures – physical barrier to microorganisms and foreign matter.

• Acid PH helps to prevent infection

• Sensory perception- Allows you to feel pain, pressure heat this helps us to identify potential dangers and avoid injury

• Thermoregulation- Blood vessels constrict or dilate to raise or lower body temperature. Sweat production promotes cooling

• Excretion –Transmits small amounts of water and body waste via sweatHelps to prevent dehydration.

• Metabolism-Photochemical reaction in the skin produces Vitamin D essential for metabolism of calcium

• Absorption-Some substances can be absorbed directly into blood stream

• Communication

Functions of the skin that declines with age.

• Flattening of the dermal-epidermal junction, increased susceptibility to friction/ shearing forces resulting in blistering.

• Decreased sensitivity to pain perception• Epidermis becomes thinner and flatter , uneven distribution

of melanocytes leading to uneven pigmentation.• Skin becomes wrinkled due to depletion of elastic fibres.• Skin becomes dry as a result of atrophy of sebaceous glandsBaraboski (2003) and Beldon (2006)

How do wounds heal?

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Classification of wound healing

• Wounds that heal by primary intention e.g. incisional wounds

• Wounds that heal by secondary intention e.g. pressure ulcers

• Wounds that heal by tertiary intention e.g. delayed suture

• Wounds characterised by whether they are acute or chronic

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Acute wounds

Characterised by:• No underlying aetiology i.e. trauma• Short duration• Normal inflammatory phase• Heal and do not breakdown

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Chronic wounds

Characterised by:• Underlying pathology e.g. venous

insufficiency• Prolonged duration• Hyperactive state• Persistent state of inflammation

• Wounds go through 4 distinct phases

Normal Wound Healing Response

HAEMOSTASIS

INFLAMMATION

PROLIFERATION

MATURATION

MINUTES DAYS WEEKS MONTHS / YEARS

Platelets

Fibrin

Neutrophils

Macrophages

Lymphocytes

Proteoglycans

Fibroblasts

Collagen

Angiogenesis

Collagen remodelling

Scar maturation

(whru)

Haemostasis• Starts immediately after injury.• Blood vessel contraction

(vasoconstriction)

Inflammatory phase• Occurs between 0-3 days

Proliferation• 0-24 days

Maturation• 20 days – 2 years• Closure of wound and re-epithelisation.• Scar maturation

What factors may affect wound healing?

Factors Affecting Healing Systemic

•Age •Anaemia•Nutrition• Medications e.g.: Anti inflammatory, Cytotoxic drugs, steroids •Chronic health conditions eg :Diabetes Mellitus•Systemic infection (Bowler & Davies, 1999)•Oxygenation•Smoking•Psychological factors•Temperature

Factors affecting healing Local Factors

•Blood supply•Denervation•Haematoma•Local Infection•Duration•Wound bed condition•Anatomical site•Size of wound

• Assessment of a wound is the responsibility of the qualified member of staff

• You should ensure that this has been undertaken and a treatment plan has been established.

Remember

The selection of dressings or bandages without accurately undertaking a wound assessment taking into account underlying factors that may delay wound healing may result in costly treatments that are inappropriate and are not successful!

Clinical appearance of wound bed

Colour Physiological StateBlack Necrotic Yellow SloughyRed GranulatingPink EpithelializingGreen Infected?

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Characteristics of granulation tissue

Healthy tissue

Bright red

Moist

Shiny

Does not bleed

Unhealthy tissue

Dark red

Dehydrated

Dull

Bleeds easily

S

Granulating

(WHRU)

(WHRU)

Necrosis

Slough

Clinical appearance of

surrounding skin

Maceration

Excoriation

Erythema and oedema

Eczema and dry skin

Exudate

• Quantity – Small , moderate copious is dressing containing exudate?

• Colour – Green? serous?, haemoserrous?• Consistency – Thick?Thin,

Pain

• When does it occur?• How bad (intense) is it?• How does the patient describe it?• What makes it better?

• If there are any changes in the wound report immediately to your nurse in charge

• Any delay in a reassessment may result in inappropriate treatment