1. Growth Renewal and Functions
Skin
Growth Renewal and Functions
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2. © Clinical Science Applied to Nursing /SONMS/Cardiff University/092005
Learning Outcomes
Describe the strata of the epidermis: Briefly
describe cell communication
Re cell specification within the epidermis
outline functions of
Keratinocytes
Melanocytes
Merkel cells
Langerhan cells
Describe the basement membrane
Describe the Dermis
Briefly describe the papillary & reticular layers
Explain the structure & function of skin hair, nails & glands
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3. © Clinical Science Applied to Nursing /SONMS/Cardiff University/092005
OVERVIEW of SKIN = DERM
OUTSIDE SKIN = (Epi dermis) includes,
hair,
nails,
glands.
Nerves
Touch & pain, receptors.
INSIDE SKIN = (Dermis), includes,
blood vessels,
blood cells,
muscle tissue.
connective tissues
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4. © Clinical Science Applied to Nursing /SONMS/Cardiff University/092005
THE EPIDERMIS
Epidermal cells produce:
KERATIN-
fibrous protein
virtually water proof
MELANIN-
Pigment
protects against UV light
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5. One cell divides to form 2 identical cells
Mitosis = Cell division –
One cell divides to form 2 identical cells
from the Base Layer
Cells change progressively in the epidermis
Cell appearance changes as they migrate to the top
Cells migrate to replace cells worn away
SCRATCH YOUR SKIN WITH YOUR NAILS AND YOU WILL TAKE AWAYS THOUSANDS OF TOP CELLS THAT HAVE TO BE REPLACED
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6. © Clinical Science Applied to Nursing /SONMS/Cardiff University/092005
The base layer
A single layer of cells
(columnar or cuboidal)
continually divide from a fixed position
producing new cells i.e.
Keratinocytes,
Langerhan's cells,
Melanocytes and
Merkel cells.
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The stratum spinosum -
Highly interactive: Cell wall is constantly mobile,
New cells differentiate (change)
They also migrate toward the surface.
The stratum spinosum contains:
Keratinocytes,
Langerhan's cells,
Melanocytes
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Stratum Granulosum
Cells have changed form & function by this stage
Some loose cytoplasm
Some loose DNA,
Others continue to synthesis keratin.
The dying process starts
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9. © Clinical Science Applied to Nursing /SONMS/Cardiff University/092005
KERATIN
Soft KERATIN-found in skin.
Hard KERATIN found nails.
Both protect living cells that lie beneath.
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10. © Clinical Science Applied to Nursing /SONMS/Cardiff University/092005
Keratinocytes-
Building block of the Epidermis.
Joined by the basement membrane & cell to cell by hemidesmones
Produce KERATIN.
immunologic tasks
Example:
Keratinocytes secrete Interleukin-1, & pass this to Langerhan cells in the skin
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11. Infection Control & the Skin
Foreign particles enter Keratinized epidemis,
particles stick to Langerhan's cells.
Foreign body = antigen
Langerhan cells offer antigen to white blood cells (lymphocytes) in the skin.
Lymphocytes also receive interleukin-1 from Langerhan's cells and produce interleukin-2.
Interleukin-2. binds to receptors on other lymphocytes to stimulate reproduction of many lymphocytes -this starts the fight against infection
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The stratum corneum
Dead keratinized multi-layered strata.
Face approx 15 layers.
Palms over 100 layers.
Arms approx 25 layers.
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Langerhan's cells
Lie in the stratum spinosum.
They are derived from Stem cells from the bone marrow.
These cells also have dendrites - look much like tennis rackets
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Melanocytes
Synthesise pigment granules.
PIGMENT GRANULES = MELANOSOMES - these contain melanin, (brown colour).
Melanosomes are transferred to Keratinocytes through dendritic processes
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MELANIN & Skin Colour
Melanocytes - scattered throughout the base layer of the epidermis
Melanocytes
the same in most races- the amount of melanin produced by the cells determines skin colour.
Genes, Sunlight, Hormones
secreted by the pituitary gland control the amount of Melanin produced by Melanocytes.
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Colour Transfer
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Merkel Cells
Free nerve endings attached to these epidermal cells.
Found in the skin of the fingers, toes, lips, mouth and all touch areas.
Their function is to detect touch.
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Merkel cells
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19. Distribution of nerve receptors
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20. BASEMENT MEMBRANE ZONE
Below the epidermis
Anchoring complex joins epidermis to dermis.
Anchoring complex is composed of hemidesmosomes:
A ‘spot weld’ that holds cells together-
Requires anchoring filaments, fibrils & glue.
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The Filaments & ‘Glue’
Collagen fibres + Glycoproteins
Elasticity Adhesion, strength anchorage.
This also forms defence barrier
Allows lymphocytes, neutrophils and langerhan's cells to penetrate
Bars larger molecules e.g. most bacteria
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22. Dermis-PAPILLARY LAYER
Defence against!
papilla
Capillary Dilation to increase blood flow
Capillary blood flow
Nerve Fibres
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THE RETICULAR LAYER
Tough - durable
Random collagen fibres
- this gives rise to the cleavage lines on the body and finger prints.
Within this
blood & lymph vessels
nerve endings, fat, oils
glands & hair roots
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24. Special Glands in the epidermis.
SWEAT GLANDS -watery secretions – evaporates to cool the body
SEBACEOUS GLANDS -oily sebum – protective: lubricates & prevents water loss-
also thought to have an antibacterial function
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Glands
ECCRINE- Sweat
Transports sweat to regulate body temperature
APOCRINE- Sebaceous
Opens from the hair follicle
Secretes oily substance
(mixes with bacteria on skin surface -)
How do you notice this?
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26. © Clinical Science Applied to Nursing /SONMS/Cardiff University/092005
Skin Structures
HAIR requires a hair follicle & muscle to move.
NAILS- a Hardened keratinized plate
Sebaceous glands lubricate the hair
(the muscle under the sebaceous gland, attached to the hair, also allows for thermoregulation.
Apocrine glands (axilla/groin) lubricates Skin and gives off an odour
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27. © Clinical Science Applied to Nursing /SONMS/Cardiff University/092005
Recap
Several important layers & cells
A basement glue and cell to cell connection points
Specialised cells for special functions:
Immune response……………………….………
Water proofing……………………………………
Protection from UV light……………………….….
Thermoregulation…………………………………
Excretion…………………………………………….
Sensory perception………………………………….
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