The Integumentary System

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The Integumentary System

• Chapter 5

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Integumentary System

• The Body Covering
• Includes skin, nails hairs
• Skin cutaneous membrane

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Structure

• Two main parts
• Epidermis- surface epithelial layer
• Dermis -deeper connective tissue layer
• Deep dermis not part of the skin subcutaneous
  layer or Hypodermis

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Figure 5.1
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Epidermis

• Keratinized stratified squamous epithelium
• 4 cell types
• Keratinocytes
• Melanocytes
• Langerhans cells
• Merkel cells

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Epidermal Cells

• Keratinocytes
• 90 of epidermal cells
• 4-5 layers
• Produce keratin
• Protect skin
• Waterproof skin

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Epidermal Cells

• Melanocytes - produce melanin
• Transfer pigment to keratinocytes
• 8 of epidermal cells

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Epidermal Cells

• Langerhans Cells- immune response
• Merkel cells sensory
• Include tactile disc and neuron
• touch sensation

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Epidermal Layers

• Generally 4 strata (layers)
• Stratum basale includes stem cells
• Stratum spinosum 8-10 cell layer
• Cells beginning to look flattened
• Stratum granulosum keratin
• Losing cell organelles and nuclei
• Include lamellar granules waterproofing lipid
• Stratum corneum flattened dead cells
• Cells shed and are replaced from below- mostly
  keratin-filled

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Skin Color

• Melanin- dark color
• Darkness depends on amount of melanin produced.
• gives some protection against UV
• Carotene- yellow orange
• In stratum corneum and adipose layers-
• Hemoglobin in blood- pink-red
• Depends on blood flow

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Accessory Structures

• Hair
• Skin glands
• Nails

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Hair

• Found on most skin surfaces
• Not 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

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Figure 5.3
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Glands

• 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, beard
• Contain other cell material and produce pheromes
• Ceruminous Glands- external auditory canal
• Combine with sebum to produce earwax

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Nails

• Plates of packed hard dead keratinized cells
• Nail body- major visible portion
• Free edge- part extending past finger or toe
• Root part not visible

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Figure 5.4a
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Figure 5.4b
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Functions

• Temperature Regulation
• Protection
• Sensory reception
• Excretion Absorption -small
• Vitamin D synthesis

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Aging

• 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