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Chapter 5:
The Integumentary System
© 2013 John Wiley & Sons, Inc. All rights reserved.
The Integumentary System
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Skin
Accessory structures of the skin
Functions of the skin
Aging and the integumentary system
© 2013 John Wiley & Sons, Inc. All rights reserved.
Skin
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Two functional layers
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____ – outer layer consisting of a stratified
squamous epithelium waterproofed and hardened
by keratin
____ – dense connective tissue containing blood
vessels, nerve endings, sweat and oil glands, and
hair follicles and associated structures
© 2013 John Wiley & Sons, Inc. All rights reserved.
Skin
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Two functional layers
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Epidermis – outer layer consisting of a stratified
squamous epithelium waterproofed and hardened
by keratin
Dermis – dense connective tissue containing
blood vessels, nerve endings, sweat and oil
glands, and hair follicles and associated
structures
© 2013 John Wiley & Sons, Inc. All rights reserved.
Skin
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The skin and hairs and other structures such as nails constitute the
integumentary system.
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The principal parts of the skin are the superficial epidermis and deeper
dermis. The dermis overlies and attaches to the subcutaneous (subQ)
layer.
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Epidermal cells include keratinocytes, melanocytes, Langerhans cells,
and Tactile cells. The epidermal layers, from deepest to most superficial,
are the stratum basale (undergoes cell division and produces all other
layers), stratum spinosum (provides strength and flexibility), stratum
granulosum (contains keratin and lamellar granules), stratum lucidum
(present only in palms and soles), and stratum corneum (sloughs off dead
skin).
© 2013 John Wiley & Sons, Inc. All rights reserved.
Skin
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The dermis consists of two regions. The superficial region is
areolar connective tissue containing blood vessels, nerves,
hair follicles, dermal papillae, and corpuscles of touch
(Meissner corpuscles). The deeper region is dense, irregularly
arranged connective tissue containing adipose tissue, hair
follicles, nerves, oil glands, and sweat glands.
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Skin color is due to the pigments melanin, carotene, and
hemoglobin.
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In tattooing, a pigment is deposited with a needle in the
dermis. Body piercing is the insertion of jewelry through an
artificial opening.
© 2013 John Wiley & Sons, Inc. All rights reserved.
Skin
© 2013 John Wiley & Sons, Inc. All rights reserved.
Skin
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Layers of the epidermis
Epidermal layers from deep to superficial
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Stratum basale
Stratum spinosum
Stratum granulosum
Stratum lucidum (thick, hairless skin only)
Stratum corneum
© 2013 John Wiley & Sons, Inc. All rights reserved.
Skin
© 2013 John Wiley & Sons, Inc. All rights reserved.
Accessory Structures of the Skin
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Accessory structures of the skin develop from the epidermis of an
embryo and include hair, skin glands (sebaceous, sudoriferous, and
ceruminous), and nails.
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Hairs are threads of fused, dead keratinized cells that function in
protection. They consist of a shaft above the surface, a root that
penetrates the dermis and subcutaneous layer, and a hair follicle.
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Associated with hairs are bundles of smooth muscle called arrector
pili and sebaceous glands or oil glands. Sebaceous glands are
usually connected to hair follicles; they are absent in the palms and
soles. Sebaceous glands produce sebum, which moistens hairs and
waterproofs the skin.
© 2013 John Wiley & Sons, Inc. All rights reserved.
Accessory Structures of the Skin
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There are two types of sweat glands or sudoriferous glands: eccrine and
apocrine. Eccrine sweat glands have an extensive distribution; their ducts
terminate at pores at the surface of the epidermis, and their main function is
to help regulate body temperature. Apocrine sweat glands are limited in
distribution, and their ducts open into hair follicles. They begin functioning at
puberty and are stimulated during emotional stress and sexual excitement.
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Ceruminous glands are modified sudoriferous glands that secrete
cerumen. They are found in the external auditory canal.
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Nails are hard, dead, keratinized epidermal cells covering the terminal
portions of the fingers and toes. The principal parts of a nail are the nail
body, free edge, nail root, lunula, cuticle, and nail matrix. Cell division of
the matrix cells produces new nails.
© 2013 John Wiley & Sons, Inc. All rights reserved.
Accessory Structures of the Skin
© 2013 John Wiley & Sons, Inc. All rights reserved.
Accessory Structures of the Skin
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Glands – single or groups of epithelial cells that
secrete a substance
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The glands associated with the skin include sebaceous,
sudoriferous (sweat), and ceruminous glands
Sebaceous glands – secrete an oily substance
called sebum that keeps hair from drying out,
prevents excessive evaporation of water from the
skin, keeps the skin soft, and inhibits the growth of
certain bacteria
Eccrine sweat glands – most prevalent sweat glands
distributed throughout most of the body, especially
in the skin of the forehead, palms, and soles
© 2013 John Wiley & Sons, Inc. All rights reserved.
Accessory Structures of the Skin
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Apocrine sweat glands – found mainly in the
skin of the axilla (armpit), groin, areolae
(pigmented areas around the nipples) of the
breasts, and bearded regions of the face in
adult males
Ceruminous glands – present in the outer ear
canal the combined secretion of the
ceruminous and sebaceous glands is a
yellowish secretion called cerumen or earwax
© 2013 John Wiley & Sons, Inc. All rights reserved.
Accessory Structures of the Skin
© 2013 John Wiley & Sons, Inc. All rights reserved.
Functions of the Skin
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Skin functions include body temperature regulation,
protection, sensation, excretion and absorption, and synthesis
of vitamin D.
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The skin participates in body temperature regulation by
liberating sweat at its surface and by adjusting the flow of
blood in the dermis.
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The skin provides physical, chemical, and biological barriers
that help protect the body.
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Cutaneous sensations include tactile sensations, thermal
sensations, and pain.
© 2013 John Wiley & Sons, Inc. All rights reserved.
Anatomy Overview:
• The Integument and Disease Resistance
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Aging and the Integumentary System
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Most effects of aging occur when an
individual reaches the late forties.
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Among the effects of aging are wrinkling, loss
of subcutaneous fat, atrophy of sebaceous
glands, and decreases in the number of
melanocytes and Langerhans cells.
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Focus on Homeostasis
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Focus on Homeostasis
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Normal Mole and Malignant Melanoma
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Burns
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Rule of Nines
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End of Chapter 5
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© 2013 John Wiley & Sons, Inc. All rights reserved.