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The Integumentary The Integumentary SystemSystem
The Integumentary The Integumentary SystemSystem
Chapter 5
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Integumentary SystemIntegumentary SystemIntegumentary SystemIntegumentary System
• The Body Covering• Includes: skin, nails & hairs• Skin = cutaneous membrane
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StructureStructureStructureStructure
• Two main parts =• Epidermis- surface epithelial
layer• Dermis -deeper connective tissue
layer• Deep dermis not part of the skin =
subcutaneous layer or Hypodermis
Figure 5.1
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EpidermisEpidermisEpidermisEpidermis
• Keratinized stratified squamous epithelium
• 4 cell types:• Keratinocytes• Melanocytes• Langerhans cells• Merkel cells
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Epidermal CellsEpidermal CellsEpidermal CellsEpidermal Cells
• Keratinocytes• 90% of epidermal cells• 4-5 layers• Produce keratin• Protect skin• Waterproof skin
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Epidermal CellsEpidermal CellsEpidermal CellsEpidermal Cells
• Melanocytes - produce melanin
• Transfer pigment to keratinocytes
• 8% of epidermal cells
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Epidermal CellsEpidermal CellsEpidermal CellsEpidermal Cells
• Langerhans Cells- immune response
• Merkel cells – sensoryInclude tactile disc and neuron = touch sensation
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Epidermal LayersEpidermal LayersEpidermal LayersEpidermal Layers
• Generally 4 strata (layers)• Stratum basale –includes stem cells• Stratum spinosum – 8-10 cell layer
Cells beginning to look flattened
• Stratum granulosum –keratinLosing cell organelles and nucleiInclude lamellar granules = waterproofing lipid
• Stratum corneum – flattened dead cells
Cells shed and are replaced from below- mostly keratin-filled
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Skin ColorSkin ColorSkin ColorSkin Color
• Melanin- dark colorDarkness depends on amount of melanin
produced. gives some protection against UV
• Carotene- yellow orangeIn stratum corneum and adipose layers-
• Hemoglobin in blood- pink-redDepends on blood flow
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Accessory StructuresAccessory StructuresAccessory StructuresAccessory Structures
• Hair• Skin glands• Nails
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HairHairHairHair
• Found on most skin surfacesNot on palmar surfaces of hand and fingers or
plantar surfaces of feet
• Made of fused keratinized cells• Consists of shaft & root• Surrounded by hair follicle
Base is bulb which includes growing matrix producing cells
• Nerves- hair root plexuses• Muscle- arrector pili
Figure 5.3
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GlandsGlandsGlandsGlands
• sebaceous gland- secrete oily sebum
Connected to hair follicles
• sudoriferous or sweat gland• Eccrine sweat gland
Wide distribution- thermoregulation• apocrine sweat gland
Axilla, groin, areolae, beardContain other cell material and produce
pheromes
• Ceruminous Glands- external auditory canal
Combine with sebum to produce earwax
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NailsNailsNailsNails
• Plates of packed hard dead keratinized cells
• Nail body- major visible portion
• Free edge- part extending past finger or toe
• Root – part not visible
Figure 5.4a
Figure 5.4b
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FunctionsFunctionsFunctionsFunctions
• Temperature Regulation• Protection• Sensory reception• Excretion & Absorption -small• Vitamin D synthesis
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AgingAgingAgingAging
• Adolescence- can develop acne• Mostly dermis- visible ~ age 40• Loss of collagen fibers • Loss of elasticity• Loss of immune responses• Decreased melanocyte
functions- gray hair, blotches
• Thinning