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Integumentary System
Overall structure
- pEpidermis (stratified squamous epith.)
- pDermis (CT)
- p(subcutaneous layer / hypodermis)
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Functions of integument
- pProtection – physical, insulation
- pPrevention of water loss
- pTemperature regulation – capillaries, sweat glands
- pMetabolic regulation – vitamin D, Ca++ homeostasis
- pImmune defense
- pSensory reception - touch, temp, pain, pressure, vibration
- pExcretion - sweat
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Epidermis
- pKeratinized stratified squamous epithelium (keratinocytes)
- pStratum basale
- nSingle layer of columnar to cuboidal cells attached to basement membrane
- nAreolar CT deep to BM
- nStratum basale cells undergo mitosis
- pStratum spinosum
- pStratum granulosum - keratinization
- pStratum corneum – dead cells
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Stratum Basale
- pOnly layer that is mitotically active
- pSingle layer of cells directly adjacent to the dermis populated by three cell types:
- 1.Keratinocytes – most abundant and produce a water-insoluble protein (keratin) that is strong and prevents the skin from dissolving in an aqueous environment
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2.Melanocytes
- •Have long branching cytoplasmic processes that are distributed throughout this cell layer
- •Produce a black/brown/yellow-brown pigment that can absorb energy from the ultraviolet spectrum of light thus preventing damage to DNA of cells in this layer and possibly preventing a form of skin cancer
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Tactile cells
– sensitive to touch
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