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The Integumentary System
Mosby items and derived items © 2010, 2006, 2002, 1997, 1992 by Mosby, Inc., an affiliate of Elsevier Inc.
The Skin
• Structure—two primary layers called
epidermis and dermis
– Epidermis
• Outermost and thinnest primary layer of skin
• Composed of several layers of stratified
squamous epithelium
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Mosby items and derived items © 2010, 2006, 2002, 1997, 1992 by Mosby, Inc., an affiliate of Elsevier Inc.
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Mosby items and derived items © 2010, 2006, 2002, 1997, 1992 by Mosby, Inc., an affiliate of Elsevier Inc.
The Skin
• Structure
– Epidermis
• Stratum germinativum—innermost (deepest) layer of cells
• continually reproduce
• new cells move toward the surface
– Sometimes called the pigment layer
– Pigment cells called melanocytes
– Produce the brown pigment melanin
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Mosby items and derived items © 2010, 2006, 2002, 1997, 1992 by Mosby, Inc., an affiliate of Elsevier Inc.
The Skin
• Keratin- tough, waterproof protein
–Fill cells as they move toward surface
–Flake off at surface
• Stratum corneum—outermost layer of
keratin-filled cells
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Mosby items and derived items © 2010, 2006, 2002, 1997, 1992 by Mosby, Inc., an affiliate of Elsevier Inc.
The Skin
• Structure
– Epidermis
• Skin color changes
– Pink flush indicates increased blood
volume or increased blood oxygen
– Cyanosis—bluish gray color indicates
decreased blood oxygen level
– Vitiligo—patchy light skin areas resulting
from acquired loss of epidermal
melanocytes (Figure 6-4)
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Mosby items and derived items © 2010, 2006, 2002, 1997, 1992 by Mosby, Inc., an affiliate of Elsevier Inc.
The Skin
– “mask of pregnancy”- Increased skin
pigmentation caused by hormonal changes
in pregnant women
– Freckles—small, flat macules—common
normal skin pigment variation
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Mosby items and derived items © 2010, 2006, 2002, 1997, 1992 by Mosby, Inc., an affiliate of Elsevier Inc.
The Skin
• Dermal-epidermal junction
• specialized area of contact between the epidermis
and dermis
• sometimes described as “spot welds”
• provide support for epidermis
• weakened or destroyed junctions can cause
blisters
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Mosby items and derived items © 2010, 2006, 2002, 1997, 1992 by Mosby, Inc., an affiliate of Elsevier Inc.
The Skin
• Structure
– Dermis
• Deeper and thicker of the two primary skin
layers
• Composed largely of connective tissue
• Upper area of dermis characterized by
– parallel rows of peglike dermal papillae
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Mosby items and derived items © 2010, 2006, 2002, 1997, 1992 by Mosby, Inc., an affiliate of Elsevier Inc.
• Thick skin has parallel friction ridges and no
hairs
• Thin skin has irregular, shallow grooves and
hair
• Deeper area of dermis
– filled with network of tough collagenous and
stretchable elastic fibers
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Mosby items and derived items © 2010, 2006, 2002, 1997, 1992 by Mosby, Inc., an affiliate of Elsevier Inc.
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Mosby items and derived items © 2010, 2006, 2002, 1997, 1992 by Mosby, Inc., an affiliate of Elsevier Inc.
The Skin
• Structure
– Dermis
• Number of elastic fibers decreases with age
and contributes to wrinkle formation
– Striae—“stretch marks”; elongated marks
caused by overstretching of skin
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Mosby items and derived items © 2010, 2006, 2002, 1997, 1992 by Mosby, Inc., an affiliate of Elsevier Inc.
The Skin
• Structure
– Dermis
•
•
•
•
•
contains nerve endings
muscle fibers
hair follicles
sweat and sebaceous glands
many blood vessels
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Mosby items and derived items © 2010, 2006, 2002, 1997, 1992 by Mosby, Inc., an affiliate of Elsevier Inc.
–Birthmarks—malformation of dermal
blood vessels
»Strawberry hemangioma
»Port-wine stain
»Stork bite
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Mosby items and derived items © 2010, 2006, 2002, 1997, 1992 by Mosby, Inc., an affiliate of Elsevier Inc.
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Mosby items and derived items © 2010, 2006, 2002, 1997, 1992 by Mosby, Inc., an affiliate of Elsevier Inc.
The Skin
• Appendages of the skin
– Hair
• Hair follicle - epidermal tubelike structure
from which hair grows
• Hair papilla- cap-shaped cluster of cells from
which hair growth begins
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Mosby items and derived items © 2010, 2006, 2002, 1997, 1992 by Mosby, Inc., an affiliate of Elsevier Inc.
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Mosby items and derived items © 2010, 2006, 2002, 1997, 1992 by Mosby, Inc., an affiliate of Elsevier Inc.
The Skin
• Appendages of the skin
– Hair
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•
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Hair root-hidden in follicle
Hair shaft- visible part of hair
Alopecia (Figure 6-8)—hair loss
Arrector pili—specialized smooth muscle
– produces “goose pimples”
– causes hair to stand up straight
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Mosby items and derived items © 2010, 2006, 2002, 1997, 1992 by Mosby, Inc., an affiliate of Elsevier Inc.
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Mosby items and derived items © 2010, 2006, 2002, 1997, 1992 by Mosby, Inc., an affiliate of Elsevier Inc.
The Skin
• Appendages of the skin
– Receptors
• Specialized nerve endings
• Make it possible for skin to act as a sense
organ
– Meissner (tactile) corpuscle—capable of detecting
light touch
– Lamellar (Pacini) corpuscle—capable of detecting
pressure
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Mosby items and derived items © 2010, 2006, 2002, 1997, 1992 by Mosby, Inc., an affiliate of Elsevier Inc.
The Skin
• Nails
– Produced by epidermal cells
– Cover terminal ends of fingers and toes
– Nail bed may change color with change in blood
flow
– Nail body- visible part
– Root -lies in a groove, hidden by cuticle
– Lunula -crescent-shaped area nearest root
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Mosby items and derived items © 2010, 2006, 2002, 1997, 1992 by Mosby, Inc., an affiliate of Elsevier Inc.
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Mosby items and derived items © 2010, 2006, 2002, 1997, 1992 by Mosby, Inc., an affiliate of Elsevier Inc.
The Skin
• Nails
– Normal variations in nail structure
• Longitudinal ridges in light-skinned individuals
• Pigmented bands in dark-skinned individuals
– Abnormal variations in nail structure
• Onycholysis—separation of nail from nail bed
• Pitting—common in psoriasis
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Mosby items and derived items © 2010, 2006, 2002, 1997, 1992 by Mosby, Inc., an affiliate of Elsevier Inc.
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Mosby items and derived items © 2010, 2006, 2002, 1997, 1992 by Mosby, Inc., an affiliate of Elsevier Inc.
The Skin
• Skin glands—two main types
– Sweat, or sudoriferous
– Sebaceous
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Mosby items and derived items © 2010, 2006, 2002, 1997, 1992 by Mosby, Inc., an affiliate of Elsevier Inc.
The Skin
• Skin glands
– Sweat, or sudoriferous, glands
• Eccrine sweat gland
– Most numerous and widespread of the sweat glands
– Produce perspiration or sweat, flows out through
pores (openings) on skin surface
– Function throughout life
– Assist in body heat regulation
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Mosby items and derived items © 2010, 2006, 2002, 1997, 1992 by Mosby, Inc., an affiliate of Elsevier Inc.
The Skin
• Skin glands
– Sweat or sudoriferous glands
• Apocrine sweat glands
– Found primarily in axilla and around genitalia
– Secrete a thicker, milky secretion, different from
eccrine perspiration
– Breakdown of secretion by skin bacteria produces
odor
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Mosby items and derived items © 2010, 2006, 2002, 1997, 1992 by Mosby, Inc., an affiliate of Elsevier Inc.
The Skin
• Skin glands
– Sebaceous glands
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Secrete oil or sebum for hair and skin
Secretion increases during adolescence
Amount of secretion regulated by sex hormones
Sebum in sebaceous gland ducts may darken to
form a blackhead
– Acne vulgaris—inflammation of sebaceous gland
ducts
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Mosby items and derived items © 2010, 2006, 2002, 1997, 1992 by Mosby, Inc., an affiliate of Elsevier Inc.
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Mosby items and derived items © 2010, 2006, 2002, 1997, 1992 by Mosby, Inc., an affiliate of Elsevier Inc.
Functions of the Skin
• Protection—first line of defense
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Against infection by microbes
Against ultraviolet rays from sun
Against harmful chemicals
Against cuts and tears
Bruising can cause discoloration as blood
released from damaged vessels breaks down
– Skin grafts may be needed to replace skin
destroyed by disease or trauma
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Mosby items and derived items © 2010, 2006, 2002, 1997, 1992 by Mosby, Inc., an affiliate of Elsevier Inc.
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Mosby items and derived items © 2010, 2006, 2002, 1997, 1992 by Mosby, Inc., an affiliate of Elsevier Inc.
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Mosby items and derived items © 2010, 2006, 2002, 1997, 1992 by Mosby, Inc., an affiliate of Elsevier Inc.
Functions of the Skin
• Temperature regulation
– Skin can release almost 3000 calories of
body heat per day
– Mechanisms of temperature regulation
• Regulation of sweat secretion
• Regulation of flow of blood close to the body
surface
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Mosby items and derived items © 2010, 2006, 2002, 1997, 1992 by Mosby, Inc., an affiliate of Elsevier Inc.
Functions of the Skin
• Sense organ activity
– Receptors serve as receivers for the body,
keeping it informed of changes in its
environment
– Skin can detect sensations of light touch,
pressure, pain, heat, and cold
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Mosby items and derived items © 2010, 2006, 2002, 1997, 1992 by Mosby, Inc., an affiliate of Elsevier Inc.
Skin Cancer
• Three common types
– Squamous cell carcinoma—the most
common type, characterized by hard,
raised tumors
– Basal cell carcinoma—characterized by
papules with a central crater; rarely
spreads
– Melanoma—malignancy in a nevus (mole);
the most serious type
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Mosby items and derived items © 2010, 2006, 2002, 1997, 1992 by Mosby, Inc., an affiliate of Elsevier Inc.
Skin Cancer
• The most important causative factor in
common skin cancers is exposure to
sunlight
• Kaposi sarcoma, characterized by
purple lesions, is associated with AIDS
and other immune deficiencies
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Mosby items and derived items © 2010, 2006, 2002, 1997, 1992 by Mosby, Inc., an affiliate of Elsevier Inc.
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Mosby items and derived items © 2010, 2006, 2002, 1997, 1992 by Mosby, Inc., an affiliate of Elsevier Inc.