Transcript Human Anatomy & Physiology I

Chapter 5
The Integumentary
System
Copyright 2010, John Wiley & Sons, Inc.
End of Chapter 5
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Integumentary System
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The body’s covering
Includes: skin, nails, and hairs
Skin: cutaneous membrane
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Structure
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Two main parts
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Epidermis - surface epithelial layer
Dermis - deeper connective tissue layer
Subcutaneous (subQ) layer or hypodermis
lies deep to dermis; is not part of the skin
Copyright 2010, John Wiley & Sons, Inc.
Integumentary System
Copyright 2010, John Wiley & Sons, Inc.
Epidermis
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Keratinized stratified squamous epithelium
Cell types (4):
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Keratinocytes
Melanocytes
Langerhans cells
Merkel cells
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Epidermal Cells
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Keratinocytes
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90% of epidermal cells
4-5 layers
Produce keratin
Protects skin
Waterproofs skin
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Epidermal Cells
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Melanocytes
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Produce melanin that gives color to skin, hairs
Transfer pigment to keratinocytes
Make up 8% of epidermal cells
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Epidermal Cells
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Langerhans cells
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Immune response
Merkel cells
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Sense of touch
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Consist of tactile disc and neuron for touch sensation
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Epidermal Layers
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Four Layers (strata)
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Stratum basale
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Stratum spinosum: 8-10 cell layer
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Cells beginning to look flattened
Stratum granulosum makes keratin
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Includes stem cells; new cells arise here
Losing cell organelles and nuclei
Have waterproofing lipid
Stratum corneum: flattened dead cells
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Cells here consist mostly of keratin.
Cells here are shed and replaced from below.
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Skin Color
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Melanin: dark color
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Carotene: yellow orange
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Darkness depends on amount of melanin
produced.
Provides some protection against UV rays
In stratum corneum and adipose layers-
Hemoglobin in blood: pink-red
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Depends on blood flow
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Accessory Structures
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Hair
Skin glands
Nails
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Hair
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Found on most skin surfaces
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Made of fused keratinized cells
Consists of shaft and root
Surrounded by hair follicle
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Not on palmar surfaces of hand and fingers or plantar
surfaces of feet
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
Copyright 2010, John Wiley & Sons, Inc.
Hair
Copyright 2010, John Wiley & Sons, Inc.
Glands
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Sebaceous gland: secrete oily sebum
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Sudoriferous (sweat) gland
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Connected to hair follicles; keeps hair from drying
out
Eccrine sweat gland
Wide distribution- thermoregulation
Apocrine sweat gland
Axilla, groin, areolae, beard
Contain other cell material
Ceruminous (wax) gland
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Wax combines with sebum to produce earwax
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Nails
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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
Copyright 2010, John Wiley & Sons, Inc.
Functions
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Temperature regulation
Protection
Sensory reception
Excretion and absorption: small amounts
Vitamin D synthesis
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Aging
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Adolescence: can develop acne
Most effects in dermis, with visible signs of
aging by about age 40. These include:
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Loss of collagen fibers
Loss of elasticity
Loss of immune responses
Decreased melanocyte functions:
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gray hair, skin blotches
Thinning of skin and hairs
Anti-aging treatments
Copyright 2010, John Wiley & Sons, Inc.