structure and function of the integument
TRANSCRIPT
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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