Unit 321: Apply microdermabrasion

The skin

A competent therapist needs a good knowledge of the skin in order to understand treatment effects and recognise disorders.

The skin •  Is part of the integumentary system, together with the hair and nails •  Is made up of the epidermis on the outside, and dermis below •  Subcutaneous layer (adipose cells) lies beneath the dermis and is

considered part of the system •  Varies in thickness (1.5-4mm) dependent on the part of the body

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The skin •  It is one of the largest organs and covers the whole body •  The epidermis has five layers of epithelial tissue •  The skin weighs about 3.5 kilos •  It has about 640,000 sensory receptors

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Epidermis •  Forms the outer portion and is composed of five layers of stratified

squamous epithelium •  In the soles of the feet and palms of the hands the epidermis is

thickest, while in other areas – such as eyelids – the skin is thinner

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Layers of the epidermis From the top down:

•  Stratum corneum or horny layer •  Stratum lucidum or clear layer •  Stratum granulosum or granular layer •  Stratum spinosum or prickle cell layer •  Stratum germinativum or basal layer

Stratum means layer, and the second part of the name refers to its structure or function

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Layers of the epidermis

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STRATUM CORNEUM

STRATUM LUCIDUM

STRATUM GRANULOSUM

STRATUM SPINOSUM

STRATUM GERMINATIVUM

Stratum corneum •  Most superficial layer •  Consists of hardened, flattened, dead

cells and keratin •  This layer is sloughed off continually as

new cells take its place. The process – desquamation – slows with age

•  Complete cell turnover occurs every 28

to 30 days in young adults, while the same process takes 45 to 50 days in elderly adults

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Stratum lucidum •  More pronounced in thickened areas of the skin, such as the soles of

the feet and palms of the hands •  A narrow, transparent layer – hence the term clear layer •  Consists of densely packed, flat cells filled with keratin

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Stratum granulosum •  Cells have a granular appearance and are flat, and spindle shaped •  As the cells die, they fill with granules of keratin, and keratinisation

(hardening of cells) takes place •  The keratin helps to seal the skin and prevent water loss

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Stratum spinosum •  Living cells which are round and filled with fluid •  They have fibrils that interlock, allowing them to attach to other cells •  The main function of this layer is to help prevent bacteria entering

and moisture escaping

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Stratum germinativum

The deepest living layer of the epidermis where cell reproduction – mitosis – takes place. Receives a rich blood supply from the underlying papillary layer of the dermis. Contains cells called melanocytes, which produce the skin colouring or pigment known as melanin. Langerhans cells are found in this layer – they absorb and remove foreign bodies that enter the skin.

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Melanocytes

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•  Star-shaped cells that produce the skin pigment melanin, to protect it from the harmful effects of sunlight

•  Produced in abundance in dark skins, adding protection, and is totally

absent in albino skins •  UV rays of the sun activate increased production of melanocytes

causing melanin to rise, darkening the skin •  The number of melanocytes is the same for dark and light skins – it is

the melanin synthesis rate that is different

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Learner activity

•  Draw, colour and label a diagram of the epidermis •  Identify how each layer is different, and how the cells change •  State the function for each layer

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Any questions?