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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