chapter 5: the integumentary system © 2013 john wiley & sons, inc. all rights reserved

Chapter 5:The Integumentary System

© 2013 John Wiley & Sons, Inc. All rights reserved.

The Integumentary System

Skin Accessory structures of the skin Functions of the skin Aging and the integumentary system


Skin

Two functional layers ____ – 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


Skin

Two functional layers 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


Skin The skin and hairs and other structures such as nails constitute the

integumentary system.

The principal parts of the skin are the superficial epidermis and deeper dermis. The dermis overlies and attaches to the subcutaneous (subQ) layer.

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).


Skin 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.

Skin color is due to the pigments melanin, carotene, and hemoglobin.

In tattooing, a pigment is deposited with a needle in the dermis. Body piercing is the insertion of jewelry through an artificial opening.


Skin


Skin

Layers of the epidermis Epidermal layers from deep to superficial

Stratum basale Stratum spinosum Stratum granulosum Stratum lucidum (thick, hairless skin only) Stratum corneum


Skin


Accessory Structures of the Skin

Accessory structures of the skin develop from the epidermis of an embryo and include hair, skin glands (sebaceous, sudoriferous, and ceruminous), and nails.

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.

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.


Accessory Structures of the Skin 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.

Ceruminous glands are modified sudoriferous glands that secrete cerumen. They are found in the external auditory canal.

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.


Accessory Structures of the Skin Glands – single or groups of epithelial cells that

secrete a substance 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


Accessory Structures of the Skin 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


Functions of the Skin Skin functions include body temperature regulation,

protection, sensation, excretion and absorption, and synthesis of vitamin D.

The skin participates in body temperature regulation by liberating sweat at its surface and by adjusting the flow of blood in the dermis.

The skin provides physical, chemical, and biological barriers that help protect the body.

Cutaneous sensations include tactile sensations, thermal sensations, and pain.



Anatomy Overview:

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• The Integument and Disease Resistance

Aging and the Integumentary System Most effects of aging occur when an

individual reaches the late forties.

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.


Focus on Homeostasis


Normal Mole and Malignant Melanoma


Burns


Rule of Nines


End of Chapter 5

Copyright 2013 John Wiley & Sons, Inc. All rights reserved. Reproduction or translation of this work beyond that permitted in section 117 of the 1976 United States Copyright Act without express permission of the copyright owner is unlawful. Request for further information should be addressed to the Permission Department, John Wiley & Sons, Inc. The purchaser may make back-up copies for his/her own use only and not for distribution or resale. The Publishers assumes no responsibility for errors, omissions, or damages caused by the use of these programs or from the use of the information herein.


chapter 5: the integumentary system © 2013 john wiley & sons, inc. all rights reserved

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