copyright 2010, john wiley & sons, inc. chapter 5 the integumentary system
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Copyright 2010, John Wiley & Sons, Inc.
Chapter 5
The Integumentary System
Copyright 2010, John Wiley & Sons, Inc.
End of Chapter 5
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Integumentary System The body’s covering Includes: skin, nails, and hairs Skin: cutaneous membrane
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Structure Two main parts
Epidermis - surface epithelial layer Dermis - deeper connective tissue layer
Subcutaneous (subQ) layer or hypodermis lies deep to dermis; is not part of the skin
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Integumentary System
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Epidermis Keratinized stratified squamous epithelium Cell types (4):
Keratinocytes Melanocytes Langerhans cells Merkel cells
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Epidermal Cells Keratinocytes
90% of epidermal cells 4-5 layers Produce keratin Protects skin Waterproofs skin
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Epidermal Cells Melanocytes
Produce melanin that gives color to skin, hairs Transfer pigment to keratinocytes Make up 8% of epidermal cells
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Epidermal Cells Langerhans cells
Immune response
Merkel cells Sense of touch Consist of tactile disc and neuron for touch sensation
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Epidermal Layers Four Layers (strata)
Stratum basale Includes stem cells; new cells arise here
Stratum spinosum: 8-10 cell layer Cells beginning to look flattened
Stratum granulosum makes keratin Losing cell organelles and nuclei Have waterproofing lipid
Stratum corneum: flattened dead cells Cells here consist mostly of keratin. Cells here are shed and replaced from below.
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Skin Color Melanin: dark color
Darkness depends on amount of melanin produced.
Provides some protection against UV rays 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 and root Surrounded by hair follicle
Base is bulb which includes growing matrix producing cells
Nerves in hair root plexuses Muscle that pulls on hair: arrector pili
Causes hair to stand on end
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Hair
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Glands Sebaceous gland: secrete oily sebum
Connected to hair follicles; keeps hair from drying out
Sudoriferous (sweat) gland Eccrine sweat gland Wide distribution- thermoregulation Apocrine sweat gland Axilla, groin, areolae, beard Contain other cell material
Ceruminous (wax) gland Wax combines 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: cells deep to here (in nail matrix) form
new nail cells
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Nails
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Nails
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Functions Temperature regulation Protection Sensory reception Excretion and absorption: small amounts Vitamin D synthesis
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Aging Adolescence: can develop acne Most effects in dermis, with visible signs of
aging by about age 40. These include: Loss of collagen fibers Loss of elasticity Loss of immune responses Decreased melanocyte functions:
gray hair, skin blotches Thinning of skin and hairs
Anti-aging treatments