Contenu connexe Similaire à Structure and function of the integument (13) Plus de Erin Yesenosky (14) Structure and function of the integument1. Mosby items and derived items © 2012 Mosby, Inc., an imprint of Elsevier Inc. 1
Structure, Function, and Disorders
of the Integument
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Layers of the Skin
Epidermis
Dermis
Hypodermis
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Layers of the Skin (cont’d)
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Layers of the Skin (cont’d)
Dermal appendages:
Nails
Hair
Sebaceous glands
Eccrine and apocrine sweat glands
Blood supply
Papillary capillaries
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Nails
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Aging and Skin Integrity
The integumentary system reflects
numerous changes from genetic and
environmental factors
The skin becomes thinner, drier, wrinkled, and
demonstrates a change in pigmentation
Shortening and decrease in the number of
capillary loops
Fewer melanocytes and Langerhans cells
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Aging and Skin Integrity (cont’d)
The integumentary system reflects
numerous changes from genetic and
environmental factors (cont’d)
Atrophy of the sebaceous, eccrine, and
apocrine glands
Changes in hair color
Fewer hair follicles and growth of thinner hair
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Clinical Manifestations of Skin
Dysfunction
Macule
Papule
Patch
Plaque
Wheal
Nodule
Tumor
Vesicle
Bulla
Pustule
Cyst
Telangiectasia
Scale
Lichenification
Keloid
Scar
Excoriation
Fissure
Erosion
Ulcer
Atrophy
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Pressure Ulcers
Pressure ulcers result from any unrelieved
pressure on the skin, causing underlying
tissue damage
Pressure
Shearing forces
Friction
Moisture
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Pressure Ulcers (cont’d)
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Pressure Ulcers (cont’d)
Stages:
I. Nonblanchable erythema of intact skin
II. Partial-thickness skin loss involving
epidermis or dermis
III. Full-thickness skin loss involving damage or
loss of subcutaneous tissue
IV. Full-thickness skin loss with damage to
muscle, bone, or supporting structures
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Keloids
Elevated, rounded, and firm
Clawlike margins that extend beyond the
original site of injury
Excessive collagen formation during
dermal connective tissue repair
Common in darkly pigmented skin types
and burn scars
Type III collagen is increased
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Keloids (cont’d)
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Pruritus
Itching
Most common symptom of primary skin
disorders
Itch is carried by specific unmyelinated C-
nerve fibers and is triggered by a number
of itch mediators
The CNS can modulate the itch response
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Pruritus (cont’d)
Pain stimuli at lower intensities can induce
itching
Chronic itching can result in infections and
scarring due to persistent scratching
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Disorders of the Skin
Inflammatory disorders
The most common inflammatory disorders of
the skin are dermatitis or eczema
There are various types of dermatitis
The disorders are generally characterized by:
• Pruritus
• Lesions with indistinct borders
• Epidermal changes
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Inflammatory Disorders
Allergic contact dermatitis
Caused by a hypersensitivity type IV reaction
The allergen comes in contact with the skin,
binds to a carrier protein to form a sensitizing
antigen; Langerhans cells process the antigen
and carry it to T cells, which become sensitized
to the antigen
Manifestations:
• Erythema
• Swelling
• Pruritus
• Vesicular lesions
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Allergic Contact Dermatitis
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Inflammatory Disorders
Atopic dermatitis
Type I hypersensitivity: activation of mast cells,
eosinophils, T-lymphocytes, and other
inflammatory cells
Causes red, weeping crusts and chronic
inflammation, lichenification
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Inflammatory Disorders (cont’d)
Irritant contact dermatitis
Nonimmunologic inflammation of the skin
Chemical irritation from acids or prolonged
exposure to irritating substances
Symptoms similar to allergic contact dermatitis
Treatment: remove stimulus
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Inflammatory Disorders (cont’d)
Stasis dermatitis
Occurs in the legs as a result of venous stasis,
edema, and vascular trauma
Sequence of events:
• Erythema
• Pruritus
• Scaling
• Petechiae
• Ulcerations
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Inflammatory Disorders (cont’d)
Seborrheic dermatitis
Inflammation of the skin involving the scalp,
eyebrows, eyelids, nasolabial folds, and ear
canals
Scaly, white, or yellowish plaques
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Stasis and Seborrheic Dermatitis
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Papulosquamous Disorders
Psoriasis
Chronic, relapsing, proliferative skin disorder
T cell immune- mediated skin disease
Scaly, thick, silvery, elevated lesions, usually
on the scalp, elbows, or knees caused by a
high rate of mitosis in the basale layer
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Papulosquamous Disorders
(cont’d)
Psoriasis (cont’d)
Shows evidence of dermal and epidermal
thickening
Epidermal turnover goes from 26 to 30 days to
3 to 4 days
Cells do not have time to mature or adequately
keratinize
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Psoriasis
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Papulosquamous Disorders
Psoriasis (cont’d)
Plaque psoriasis
Inverse psoriasis
Guttate psoriasis
Pustular psoriasis
Erythrodermic psoriasis
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Papulosquamous Disorders
(cont’d)
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Papulosquamous Disorders
(cont’d)
Pityriasis rosea
Benign, self-limiting inflammatory disorder
Usually occurs during the winter months
Herald patch
• Circular, demarcated, salmon-pink, 3- to 4-cm lesion
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Papulosquamous Disorders
(cont’d)
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Papulosquamous Disorders
(cont’d)
Lichen planus
Benign, inflammatory disorder of the skin and
mucous membranes
Unknown origin, but T cells, adhesion
molecules, inflammatory cytokines, and
antigen presenting cells are involved
Nonscaling, violet-colored, 2- to 4-mm lesions
Wrists, ankles, lower legs, genitalia
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Lichen Planus
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Papulosquamous Disorders
Acne vulgaris
Inflammatory disease of the pilosebaceous
follicles
Acne rosacea
Inflammation of the skin that develops in
adulthood
Lesions
• Erythematotelangiectatic, papulopustular,
phymatous, and ocular
• Associated with chronic, inappropriate vasodilation
resulting in flushing and sensitivity to the sun
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Papulosquamous Disorders
(cont’d)
Lupus erythematosus
Inflammatory, autoimmune disease with
cutaneous manifestations
Discoid lupus erythematosus
• Restricted to the skin
• Photosensitivity
• Butterfly pattern over the nose and cheeks
Systemic lupus erythematosus
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Discoid Lupus Erythematosus
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Vesiculobullous Disorders
Pemphigus
Rare, chronic, blister-forming disease of the
skin and oral mucous membranes
Blisters form in the deep or superficial
epidermis
Autoimmune disease caused by circulating IgG
autoantibodies
• The antibodies are against the cell surface adhesion
molecule, desmoglein in the suprabasal layer of the
epidermis
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Vesiculobullous Disorders (cont’d)
Pemphigus (cont’d)
Tissue biopsies demonstrate autoantibody
presence
Types:
• Pemphigus vulgaris (severe)
• Pemphigus foliaceus
• Pemphigus erythematosus
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Vesiculobullous Disorders (cont’d)
Bullous pemphigoid
More benign disease than pemphigus vulgaris
Bound IgG and blistering of the subepidermal
skin layer
Subepidermal blistering and eosinophils
distinguish pemphigoid from pemphigus
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Bullous Pemphigoid
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Vesiculobullous Disorders
Erythema multiforme
Acute, recurring disorder of the skin and
mucous membranes
Associated with allergic or toxic reactions to
drugs or microorganisms
Caused by immune complexes formed and
deposited around dermal blood vessels,
basement membranes, and keratinocytes
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Vesiculobullous Disorders (cont’d)
Erythema multiforme (cont’d)
“Bull’s-eye” or target lesion
• Erythematous regions surrounded by rings of
alternating edema and inflammation
Bullous lesions form erosions and crusts when
they rupture
Affects the mouth, air passages, esophagus,
urethra, and conjunctiva
Severe forms:
• Stevens-Johnson syndrome (bullous form)
• Toxic epidermal necrolysis
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Infections
Bacterial infections:
Folliculitis
Furuncles
Carbuncles
Cellulitis
Erysipelas
Impetigo
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Furuncle
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Infections
Viral infections
Herpes zoster and varicella
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Herpes Simplex Virus
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Warts
Benign lesions caused by the human
papillomavirus (HPV)
Diagnosed by visualization
Condylomata acuminata
Venereal warts
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Fungal Infections
Fungi causing superficial skin lesions are
called dermatophytes
Fungal disorders are called mycoses;
mycoses caused by dermatophytes are
termed tinea
Tinea capitis (scalp)
Tinea pedis (athlete’s foot)
Tinea corporis (ringworm)
Tinea cruris (groin, jock itch)
Tinea unguium (nails) or onychomycosis
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Tinea Pedis
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Fungal Infections
Candidiasis
Caused by Candida albicans
Normally found on the skin, in the GI tract, and in the
vagina
Candida albicans can change from a commensal
organism to a pathogen
• Local environment of moisture and warmth
• Systemic administration of antibiotics
• Pregnancy
• Diabetes mellitus
• Cushing disease
• Debilitated states
• Age younger than 6 months
• Immunosuppression
• Neoplastic diseases
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Vascular Disorders
Cutaneous vasculitis
Results from immune complexes in the small
blood vessels
• Develops from drugs, bacterial infections, viral
infections, or allergens
Lesions
• Palpable purpura progressing to hemorrhagic bullae
with necrosis and ulceration
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Vascular Disorders (cont’d)
Urticaria
Caused by type I hypersensitivity reactions to
allergens
Histamine release causes endothelial cells of
the skin to contract
• Causes leakage of fluid from the vessels
Treatment
• Antihistamines and steroids
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Vascular Disorders (cont’d)
Scleroderma
Sclerosis of the skin that can progress to the
internal organs
The disease is associated with several
antibodies
Lesions exhibit massive deposits of collagen
with inflammation, vascular changes, and
capillary dilation
Skin is hard, hypopigmented, taut, and tightly
connected to underlying tissue
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Vascular Disorders (cont’d)
Scleroderma (cont’d)
Facial skin becomes very tight
Fingers become tapered and flexed; nails and
fingertips can be lost from atrophy
Mouth may not open completely
50% of patients die within 5 years
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Scleroderma
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Insect Bites
Bees
Mosquitoes
Flies
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Benign Tumors
Seborrheic keratosis
Keratoacanthoma
Actinic keratosis
Nevi (moles)
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Seborrheic Keratosis
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Cancer
Basal cell carcinoma
Squamous cell carcinoma
Malignant melanoma
Kaposi sarcoma
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Basal Cell Carcinoma
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Squamous Cell Carcinoma
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Malignant Melanoma
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Kaposi Sarcoma
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Burns
Partial-thickness burns
First degree
Superficial and deep partial
Second degree
Full-thickness burns
Third degree
“Rule of nines”
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Superficial Partial-Thickness Burn
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Axillary Burn Scar Contracture
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Deep Partial-Thickness Burn
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Full-Thickness Burn
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Estimating Burn Injury
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Burns
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Hypertrophic Scarring
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Cultured Epithelial Autograft
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Frostbite
Skin injury caused by exposure to extreme
cold
Usually affects fingers, toes, ears, nose,
and cheeks
The “burning reaction” is caused by
alternating cycles of vasoconstriction and
vasodilation
Inflammation and reperfusion are both part
of the pathophysiology
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Disorders of the Hair
Male-pattern alopecia
Genetically predisposed response to
androgens
Androgen-sensitive and androgen-insensitive
follicles
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Disorders of the Hair (cont’d)
Female-pattern alopecia
Associated with elevated levels of the serum
adrenal androgen dehydroepiandrosterone
sulfate
No loss of hair along the frontal hairline
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Disorders of the Hair (cont’d)
Alopecia areata
Autoimmune T cell-mediated inflammatory
disease against hair follicles that results in
baldness
Hirsutism
Androgen-sensitive areas
• Abnormal growth and distribution of hair on the face,
body, and pubic area in a male pattern that occurs in
women
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Disorders of the Nail
Paronychia
Acute or chronic infection of the cuticle
Onychomycosis
Fungal or dermatophyte infection of the nail
plate