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

Copyright 2010, John Wiley & Sons, Inc.

Structure 

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

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Integumentary System

Copyright 2010, John Wiley & Sons, Inc.

Epidermis 

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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

Copyright 2010, John Wiley & Sons, Inc.

Epidermal Cells 

Langerhans cells 

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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 

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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  

Cells here consist mostly of keratin. Cells here are shed and replaced from below.

Copyright 2010, John Wiley & Sons, Inc.

Skin Color 

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 

Depends on blood flow

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Accessory Structures 

 

Hair Skin glands Nails

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Hair 

Found on most skin surfaces 

  

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 

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 

Wax combines with sebum to produce earwax

Copyright 2010, John Wiley & Sons, Inc.

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

Copyright 2010, John Wiley & Sons, Inc.

Functions     

Temperature regulation Protection Sensory reception Excretion and absorption: small amounts Vitamin D synthesis

Copyright 2010, John Wiley & Sons, Inc.

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: 



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gray hair, skin blotches

Thinning of skin and hairs

Anti-aging treatments Copyright 2010, John Wiley & Sons, Inc.