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Structure, Function, and Disorders of the Integument

Structure, Function, and Disorders of the Integument. Chapter 44. Layers of the Skin. Epidermis Dermis Subcutaneous. Layers of the Skin. Layers of the Skin. Epidermis Stratum basale Stratum germinativum Stratum spinosum Stratum lucidum Stratum corneum. Layers of the Skin. Epidermis

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Structure, Function, and Disorders of the Integument

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  1. Structure, Function, and Disorders of the Integument Chapter 44

  2. Layers of the Skin • Epidermis • Dermis • Subcutaneous

  3. Layers of the Skin

  4. Layers of the Skin • Epidermis • Stratum basale • Stratum germinativum • Stratum spinosum • Stratum lucidum • Stratum corneum

  5. Layers of the Skin • Epidermis • Keratinocytes • Keratin • Melanocytes • Langerhans cells • Merkel cells

  6. Layers of the Skin • Dermis • Collagen, elastin, reticulum, and a gel-like ground substance • Hair follicles, sebaceous glands, sweat glands, blood vessels, lymphatic vessels, nerves • Fibroblasts, mast cells, macrophages • Subcutaneous layer • Adipocytes • Dermal and subcutaneous collagen are continuous

  7. Layers of the Skin • Dermal appendages • Nails • Hair • Sebaceous glands • Eccrine and apocrine sweat glands • Blood supply • Papillary capillaries

  8. Nails

  9. Aging and Skin Integrity • The integumentary system reflects numerous changes from genetic and environmental factors • The skin becomes thinner, drier, wrinkled, and demonstrates a changes in pigmentation • Shortening and decrease in the number of capillary loops • Fewer melanocytes and Langerhans cells • Atrophy of the sebaceous, eccrine, and apocrine glands • Changes in hair color • Fewer hair follicles and growth of thinner hair

  10. Clinical Manifestations of Skin Dysfunction • Macule • Papule • Patch • Plaque • Wheal

  11. Clinical Manifestations of Skin Dysfunction • Nodule • Tumor • Vesicle • Bulla • Pustule

  12. Clinical Manifestations of Skin Dysfunction • Cyst • Telangiectasia • Scale • Lichenification • Keloid • Scar

  13. Clinical Manifestations of Skin Dysfunction • Excoriation • Fissure • Erosion • Ulcer • Atrophy

  14. Clinical Manifestations of Skin Dysfunction • Pressure ulcers • Pressure ulcers result from any unrelieved pressure on the skin, causing underlying tissue damage • Pressure • Shearing forces • Friction • Moisture

  15. Clinical Manifestations of Skin Dysfunction • Pressure ulcers • Stages • Nonblanchable erythema of intact skin • Partial-thickness skin loss involving epidermis or dermis • Full-thickness skin loss involving damage or loss of subcutaneous tissue • Full-thickness skin loss with damage to muscle, bone, or supporting structures

  16. Clinical Manifestations of Skin Dysfunction • 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.

  17. Keloids

  18. Clinical Manifestations of Skin Dysfunction • 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 • Pain stimuli at lower intensities can induce itching • Chronic itching can result in infections and scarring due to persistent scratching

  19. Disorders of the Skin • Inflammatory disorders • The most common inflammatory disorder of the skin is dermatitis or eczema • There are various types of dermatitis • The disorders are generally characterized by pruritus, lesions with indistinct borders, and epidermal changes

  20. 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

  21. Allergic Contact Dermatitis

  22. Inflammatory Disorders • Atopic dermatitis • Type I hypersensitivity—activation of mast cells, eosinophils, T lymphs, and other inflammatory cells • Causes red, weeping crusts and chronic inflammation, lichenification • 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

  23. Atopic Dermatitis

  24. Inflammatory Disorders • Stasis dermatitis • Occurs in the legs as a result of venous stasis, edema, and vascular trauma • Sequence of events: erythema, pruritus, scaling, petechiae, ulcerations • Seborrheic (sebōrēik) dermatitis • Inflammation of the skin involving the scalp, eyebrows, eyelids, nasolabial folds, and ear canals • Scaly, white, or yellowish plaques

  25. Stasis and Seborrheic Dermatitis

  26. 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 • Shows evidence of dermal and epidermal thickening • Epidermal turnover goes from 26-30 days to 3-4 days • Cells do not have time to mature or adequately keratinize

  27. Psoriasis

  28. Papulosquamous Disorders • Psoriasis • Plaque psoriasis • Inverse psoriasis • Guttate psoriasis • Pustular psoriasis • Erythrodermic psoriasis

  29. Papulosquamous Disorders • Pityriasis rosea • Benign, self-limiting inflammatory disorder • Usually occurs during the winter months • Herald patch • Circular, demarcated, salmon-pink, 3- to 4-cm lesion

  30. Pityriasis Rosea Herald Patch

  31. Papulosquamous Disorders • 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

  32. Lichen Planus

  33. 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

  34. Papulosquamous Disorders • 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

  35. Discoid Lupus Erythematosus

  36. 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

  37. Vesiculobullous Disorders • Pemphigus • Tissue biopsies demonstrate autoantibody presence • Types • Pemphigus vulgaris (severe) • Pemphigus foliaceus • Pemphigus erythematosus

  38. Vesiculobullous Disorders • 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

  39. Bullous Pemphigoid

  40. 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 • “Bull’s-eye” or target lesion • Erythematous regions surrounded by rings of alternating edema and inflammation

  41. Vesiculobullous Disorders • Erythema multiforme • 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

  42. Erythema Multiforme

  43. Infections • Bacterial infections • Folliculitis • Furuncles • Carbuncles • Cellulitis • Erysipelas • Impetigo

  44. Furuncle

  45. Infections • Viral infections • Herpes simplex virus • Herpes zoster and varicella

  46. Herpes Simplex Virus

  47. Warts • Benign lesions caused by the human papillomavirus (HPV) • Diagnosed by visualization • Condylomata acuminata • Venereal warts

  48. 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

  49. Tinea Pedis

  50. Fungal Infections • Candidiasis • Caused by Candida albicans • Normally found on the skin, in the GI tract, and in the vagina • C. 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, and neoplastic diseases

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