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Skin Notes

Medicine Notes > Organisation of the Body Notes

This is an extract of our Skin document, which we sell as part of our Organisation of the Body Notes collection written by the top tier of Oxford students.

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SKIN
-Large organ, covers the exterior surface of the body Functions
-protection-protects the body from damaging external agents such as the
-UV
-infection-barrier to bacteria, fungus- both bacteria and fungus live on skin surface but can't penetrate tissue unless skin is breached
-excessive wetting
-mechanical insults- frictional forces experienced by soles/ventral aspect of toes
-detection of sensory stimuli- skin is the largest sensory organ and has different receptors-touch, pressure, pain, temperature
-thermoregulation- skin plays an important role in heat conservation. To loose heat, increase blood flow through rich vascular network in skin and secretion of sweat- a watery secretion of eccrine glands onto skin surface and evapouration produces a cooling effect.
-prevention of dehydration
-metabolic functions- synthesis of vitamin D3 occurs in the skin, adipose tissue stores TG Development
-epidermis formed from the ectodermal gern layer, dermis is formed from the mesoderm
-ectoderm is initially a single layer then divides into a bilaminar- outerperiderm, epidermis proper
-epidermis proper forms all 4 layers of the mature epidermis, periderm is a temporary protective membrane
-after 2 months of fertilisation, the ectodermal epidermis is invaded by cells of the neural crest region- melanocytes
-Hair forms afterwards- epithelial downgrowth into dermis
-sweat glands grow down from the epidermis, sebaceous glands formed as epithelial buds from the hair follicle
-by sixth month, periderm has keratinised and is desqumated. Structure
-specialised epithelium which has glands (sweat glands, sebaceous glands-lubricate an oily matter(sebum) into the hair follicles to lubricate the skin and hair, mammary glands). The specialised epithelial tissue also is associated with supporting tissue
-skin is arranged in layers

-epidermis (outermost layer)
-dermis
-subcutaneous tissue (hypodermis)
-the relative thickness of these layers is dependent on the area of the body and reates to specific functional specialisations; Epidermis
-surface layer of skin cells that are in contact with the external environment
-there is a constant need to replenish the epidermis, as outer surface is constantly sloughed off, so the basal layers are constantly proliferating to replace the dead cells
-sweat glands and hair follicles are down growths of this layer Structure of the epidermis

DRAW LABELLED DIAGRAM IN EXAM

-keratinised stratified squamous epithelium-keratinocytes tough keratinised upper layer formed by keratinocytes which die and produce keratin plates (squames). The outermost layer of keratin is shed and replaced by new keratinocytes from deeper layers
-the epidermis has distinct layers
-the thickness of the skin is classified according to the thickness epidermis. Thick skin has a deeper stratum corneum, stratum granulosum and stratum lucidum. Found in areas which are most exposed to abrasive forces (palm of hands, soles of feet) a) stratrum basale (basal layer)
-the low cuboidal keratinocytes express small amount of specific keratin isoforms which aggregate to form tonofilaments-merge into desmosmessingle layer of cuboidal/columnar cells attached to each other via

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