Chapter 21 The Skin Chapter Objectives Epidermis dermis

Chapter 21: The Skin Chapter Objectives • Epidermis, dermis and subcutaneous tissues. • Roles of keratin and melanin in the skin. • The glands in the skin. • The structure of hair and of nails. • Roots pertaining to the skin. Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins

Key Terms Normal Structure and Function cutaneous Pertaining to the skin (from Latin cutis, meaning “skin”) derma Skin (from Greek) dermis The layer of the skin between the epidermis and the subcutaneous tissue; the true skin or corium epidermis The outermost layer of the skin (from epi-, meaning “upon or over” and derm, meaning “skin”) hair A threadlike keratinized outgrowth from the skin (root: trich/o) hair follicle The sheath in which a hair develops integumentary system The skin and its associated glands, hair, and nails keratin A protein that thickens and toughens the skin and makes up hair and nails (root: kerat/o) Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins

Key Terms Normal Structure and Function (cont’d) melanin A dark pigment that gives color to the hair and skin and protects the skin against the sun's radiation (root melan/o) nail A platelike keratinized outgrowth of the skin that covers the dorsal surface of the terminal phalanges (root: onych/o) sebaceous gland A gland that produces sebum; usually associated with a hair follicle (root: seb/o) sebum A fatty secretion of the sebaceous glands that lubricates the hair and skin (root: seb/o) skin The tissue that covers the body; the integument (root: derm/o, dermat/o) subcutaneous tissue The layer of tissue beneath the skin; also called the hypodermis sudoriferous gland A sweat gland (root: hidr/o) Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins

Key Terms Disorders atopic dermatitis Hereditary, allergic, chronic inflammation of the skin with pruritus (itching); eczema basal cell carcinoma An epithelial tumor that rarely metastasizes and has a high cure rate with surgical removal cicatrization The process of scar formation; a scar is a cicatrix (SIK-a-triks) debridement Removal of dead or damaged tissue, as from a wound dehiscence Splitting or bursting, as when the layers of a wound separate dermatitis Inflammation of the skin, often associated with redness and itching; may be caused by allergy, irritants (contact dermatitis), or a variety of diseases dermatology Study of the skin and diseases of the skin dermatome Instrument for cutting thin sections of skin for skin grafting Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins

Key Terms Disorders (cont’d) eczema A general term for an inflammation of the skin with redness, lesions, and itching; atopic dermatitis erythema Diffuse redness of the skin escharotomy Removal of scab tissue (eschar) resulting from burns or other skin injuries evisceration Protrusion of internal organs (viscera) through an opening, as through a wound exudates Material, which may include fluid, cells, pus, or blood, that escapes from damaged tissue Kaposi sarcoma Cancerous lesion of the skin and other tissues seen most often in patients with AIDS keloid A raised, thickened scar caused by tissue overgrowth during scar formation Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins

Key Terms Disorders (cont’d) lupus erythematosus (LE) A chronic, inflammatory, autoimmune disease of connective tissue that often involves the skin; types include the more widespread systemic lupus erythematosus (SLE) and a discoid form (DLE) that involves only the skin malignant melanoma A metastasizing pigmented tumor of the skin pemphigus An autoimmune disease of the skin characterized by sudden, intermittent formation of bullae (blisters); may be fatal if untreated pressure ulcer An ulcer caused by pressure to an area of the body, as from a bed or chair; decubitus (dē-KŪ-bi-tus) ulcer, bedsore, pressure sore pruritus Severe itching Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins

Key Terms Disorders (cont’d) psoriasis A chronic hereditary dermatitis with red lesions covered by silvery scales rule of nines A method for estimating the extent of body-surface area involved in a burn by assigning percentages in multiples of nine to various regions of the body scleroderma A chronic disease that is characterized by thickening and tightening of the skin and that often involves internal organs in a form called progressive systemic sclerosis (PSS) squamous cell carcinoma An epidermal cancer that may invade deeper tissues but tends not to metastasize Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins

Supplementary Terms Symptoms and Conditions acne An inflammatory disease of the sebaceous glands and hair follicles usually associated with excess secretion of sebum; acne vulgaris actinic Pertaining to the effects of radiant energy, such as sunlight, ultraviolet light, and x-rays albinism A hereditary lack of pigment in the skin, hair, and eyes alopecia Absence or loss of hair; baldness beau lines White lines across the fingernails; usually a sign of systemic disease or injury bromhidrosis Sweat that has a foul odor because of bacterial decomposition; also called bromidrosis carbuncle A localized infection of the skin and subcutaneous tissue, usually caused by staphylococcus, and associated with pain and discharge of pus Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins

Supplementary Terms Symptoms and Conditions (cont’d) comedo A plug of sebum, often containing bacteria, in a hair follicle; a blackhead (plural: comedones) dermatophytosis Fungal infection of the skin, especially between the toes; athlete's foot (root: phyt/o means “plant”) diaphoresis Profuse sweating dyskeratosis Any abnormality in keratin formation in epithelial cells ecchymosis A collection of blood under the skin caused by leakage from small vessels erysipelas An acute infectious disease of the skin with localized redness and swelling and systemic symptoms erythema nodosum Inflammation of subcutaneous tissues resulting in tender, erythematous nodules; may be an abnormal immune response to a systemic disease, an infection, or a drug Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins

Supplementary Terms Symptoms and Conditions (cont’d) exanthema Any eruption of the skin that accompanies a disease, such as measles; a rash excoriation Lesion caused by scratching or abrasion folliculitis Inflammation of a hair follicle furuncle A painful skin nodule caused by staphylococci that enter through a hair follicle; a boil hemangioma A benign tumor of blood vessels; in the skin, called birthmarks or port wine stains herpes simplex A group of acute infections caused by herpes simplex virus. Type I herpes simplex virus produces fluid-filled vesicles, usually on the lips, after fever, sun exposure, injury, or stress; cold sore, fever blister. Type II infections usually involve the genital organs. hirsutism Excessive growth of hair Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins

Supplementary Terms Symptoms and Conditions (cont’d) ichthyosis A dry, scaly condition of the skin (from the root ichthy/o, meaning “fish”) impetigo A bacterial skin infection with pustules that rupture and form crusts; most commonly seen in children, usually on the face keratosis Any skin condition marked by thickened or horny growth. Seborrheic keratosis is a benign tumor, yellow or light brown in color, that appears in the elderly. Actinic keratosis is caused by exposure to sunlight and may lead to squamous cell carcinoma. lichenification Thickened marks caused by chronic rubbing, as seen in atopic dermatitis (a lichen is a flat, branching type of plant that grows on rocks and bark) mycosis fungoides A rare malignant disease that originates in the skin and involves the internal organs and lymph nodes. There are large, painful, ulcerating tumors. Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins

Supplementary Terms Symptoms and Conditions (cont’d) nevus A defined discoloration of the skin; a congenital vascular tumor of the skin; a mole, birthmark paronychia Infection around a nail. Caused by bacteria or fungi, and may affect multiple nails pediculosis Infestation with lice petechiae Flat, pinpoint, purplish-red spots caused by bleeding within the skin or mucous membrane (singular, petechia) photosensitization Sensitization of the skin to light, usually from the action of drugs, plant products, or other substances purpura A condition characterized by hemorrhages into the skin and other tissues rosacea A condition of unknown cause involving redness of the skin, pustules, and overactivity of sebaceous glands, mainly on the face Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins

Supplementary Terms Symptoms and Conditions (cont’d) scabies A highly contagious skin disease caused by a mite senile lentigines Brown macules that appear on sun-exposed skin in adults; liver spots shingles An acute eruption of vesicles along the path of a nerve; herpes zoster (HER-pēz ZOS-ter); caused by the same virus that causes chickenpox tinea A fungal infection of the skin; ringworm tinea versicolor Superficial chronic fungal infection that causes varied pigmentation of the skin urticaria A skin reaction marked by temporary, smooth, raised areas (wheals) associated with itching; hives Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins

Supplementary Terms Symptoms and Conditions (cont’d) venous stasis ulcer Ulcer caused by venous insufficiency and stasis of venous blood; usually forms near the ankle verruca An epidermal tumor; a wart vitiligo Patchy disappearance of pigment in the skin; leukoderma xeroderma pigmentosum A fatal hereditary disease that begins in childhood with discolorations and ulcers of the skin and muscle atrophy. There is increased sensitivity to the sun and increased susceptibility to cancer. Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins

Abbreviations BSA Body-surface area DLE Discoid lupus erythematosus FTSG Full-thickness skin graft LE Lupus erythematosus PSS Progressive systemic sclerosis PUVA Psoralen ultraviolet A SCLE Subacute cutaneous lupus erythematosus Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins

Abbreviations (cont’d) SLE Systemic lupus erythematosus SPF Sun protection factor STSG Split-thickness skin graft UV Ultraviolet UVA Ultraviolet A UVB Ultraviolet B VAC Vacuum-assisted closure Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins

Roots Pertaining to the Skin Root Meaning Example Definition of Example derm/o, dermat/o skin dermabrasion surgical procedure used to resurface the skin and remove imperfections kerat/o keratin, horny layer of the skin keratinous containing keratin; horny melan/o dark, black, melanin melanosome a small cellular body that produces melanin hidr/o sweat, perspiration anhidrosis absence of sweating seb/o sebum, sebaceous gland seborrhea excess flow of sebum trich/o hair trichomycosis fungal infection of the hair onych/o nail onychia inflammation of the nail and nail bed Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins

Anatomy of the Skin • Skin is part of integumentary system • Epidermis = outermost layer – 4 -5 layers of epithelial cells – Stratum basale • Deepest layer of epidermis • Produces new skin cells • New skin cells gradually rise to surface • As skin cells rise: • Cells die • Cells fill with keratin Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins

Anatomy of the Skin (cont’d) – Stratum corneum = outermost layer of epidermis • Flat, dead, protective cells • Constantly shed and replaced • Some cells produce melanin • Gives color to skin • Protects against sunlight Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins

Dermis & Subcutaneous Tissue • Dermis = layer beneath epidermis – Connective tissue – Nerves – Blood vessels – Lymphatics – Supports and nourishes skin • Subcutaneous tissue = layer beneath dermis – Connective tissue – Fat Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins

Cross Section of the Skin Copyright © 2011 Wolters Kluwer Health | Lippincott Williams

Associated Skin Structures • Sudoriferous glands (sweat glands) – Regulate temperature – Release watery fluid (sweat) – Sweat evaporates cooling the body • Sebaceous glands – Release sebum (oily fluid) – Lubricates hair and skin to prevent drying Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins

Associated Skin Structures (cont’d) • Hair – Nonliving material, mainly keratin – Develops within follicle – Grows from base within deep layers of skin – Functions as protection • Nails – Nonliving material, mainly keratin – Develops from growing region at proximal end – Functions as protection Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins

Clinical Aspects of the Skin • Dermatology = study of skin and skin diseases • Observation of skin, hair, nails part of every physical examination – Skin observed for color, unusual pigmentation, lesions – Palpated to evaluate texture, temperature, moisture, firmness, tenderness Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins

Wounds • Caused by: – Trauma – Surgery • Complicated by: – Infection – Hemorrhage – Dehiscence = disruption of wound layers – Evisceration = protrusion of internal organs through lesion Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins

Wound Healing • As wound heals: – Fluid and cells drain from damaged tissue

Wound Healing (cont’d) • Proper wound healing: – Cleanliness and care of lesion – Proper circulation – Good general health and nutrition – Accompanied by cicatrization (scar formation) Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins

Promotion of Healing • Vacuum-assisted closure = negative pressure to close tissues • Debridement = removal of dead or damaged tissue – Cutting or scrubbing – Enzymes – Escharotomy (removal of scar) Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins

Promotion of Healing (cont’d) • Skin graft – For deep wounds – Full thickness skin graft (FTSG) • Epidermis and dermis – Split-thickness skin graft (STSG) • Epidermis – Done with dermatome Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins

Burns • Caused by: – Hot objects – Explosions – Scalding – Electrical malfunctions – Contact with harmful chemicals – Abrasion • Assessed by: – Depth of damage – Percentage of body surface area affected Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins

Burn Categorization • Superficial partial thickness – Involves epidermis, possibly dermis – Tissue reddens, may blister • Deep partial-thickness – Involves epidermis and portions of dermis – Tissue blisters, has weeping surface Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins

Burn Categorization (cont’d) • Full-thickness – Involves full skin, possibly subcutaneous tissue – Broken, dry and pale or charred tissue – May result in loss of digits or limbs – May require skin grafting Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins

Burn Categorization (cont’d) • Percentage of body surface area – Rule of nines • Areas of body surface assigned percentages in multiples of nine – Lund and Browder • More accurate • Divides body into small areas • Estimates proportion each area contributes Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins

Burn Treatment • Includes: – Respiratory care – Administration of fluids – Wound care – Pain control – Monitoring for complications • Infections • Cardiovascular • Respiratory – Posttraumatic stress Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins

Pressure Ulcers • Necrotic skin lesions • Body resting on skin covering bony projections – Sacrum – Heel – Elbow – Ischial bone of pelvis – Greater trochanter of femur Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins

Pressure Ulcers (cont’d) • Interrupts circulation – Thrombosis – Ulceration – Death of tissue • Contributing factors: – Malnutrition – Age – Obesity – Infection Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins

Pressure Ulcers (cont’d) • Progression – First appear as redness of skin – If ignored may penetrate: • Skin • Underlying muscle • Bone – May require months to heal Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins

Pressure Ulcers (cont’d) • Prevention – Pads or mattresses to relieve pressure – Regular cleansing and drying of skin – Frequent change in position – Good nutrition Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins

Dermatitis • Inflammation of skin • Example: Eczema (atopic dermatitis) – Chronic allergic form – Exact cause unknown, but made worse by: • Allergies • Infection • Temperature extremes • Skin irritants Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins

Dermatitis (cont’d) • Other forms: – Contact dermatitis – Seborrheic dermatitis – Stasis dermatitis

Psoriasis • Chronic overgrowth of epidermis • Large erythematous plaques with silvery scales • Cause unknown, but may be linked with: – Hereditary pattern – Autoimmunity • Treatment – Topical corticosteroids – Exposure to UV light – Systemic suppression of immune system Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins

Autoimmune Disorders • Pemphigus – Characterized by formation of blisters • Occurs in skin and mucous membranes • Caused by separation of epidermal cells from underlying layers – Deep skin unprotected from infection and fluid loss – Caused by autoimmune reaction – Fatal unless immune system is suppressed Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins

Autoimmune Disorders (cont’d) • Lupus Erythematosus – Chronic inflammatory autoimmune disease of connective tissue • Discoid • Involves only the skin • Systemic lupus erythematosus • Involves skin and other organs – Symptoms • Rough, raised, violet-tinted papules • Worsened by exposure to UV rays Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins

Scleroderma • Thickening and tightening of skin • Unknown cause • Overproduction of collagen • Involves hair follicles and sweat glands • Early signs: – Raynaud disease – Skin symptoms first appear on forehead, around mouth Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins

Skin Cancer • Most common type of human cancer • Increasing rate due UV rays • Common types – Squamous cell carcinoma – Basal cell carcinoma – Malignant melanoma – Kaposi sarcoma Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins

Skin Cancer (cont’d) • Squamous cell carcinoma – Cancer of epithelial cell • Occurs in areas exposed to sunlight • Painless, firm red nodule • May invade underlying tissue • Tends not to metastasize • Treatment • Surgical removal • X-irradiation • Chemotherapy Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins

Skin Cancer (cont’d) • Basal cell carcinoma – 75% of all skin cancers – Cancer of epithelial cell • Occurs in areas exposed to sunlight • Smooth, pearly papule • After excision, cure rate 95% • Easily seen • Tends not to metastasize Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins

Skin Cancer (cont’d) • Malignant melanoma – Overgrowth of melanocytes – Metastasizing tendency – First appears as lesion – May spread superficially before invading deeper tissues – Prognosis good if lesion removed before reaching deeper tissues Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins

Skin Cancer (cont’d) • Kaposi Sarcoma – Frequently associated with AIDS – Distinct brownish area on legs – As tumor progresses: • Plaques become raised and firm – Cancer can metastasize Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins

Pretest 1. The uppermost portion of the skin is called the: (a) fossa (b)

Pretest 2. A hair grows within a sheath called the: (a) follicle (b) hyaline

Pretest 3. The glands that secrete an oily substance that lubricates the skin are the: (a) sweat glands (b) sebaceous glands (c) mammary glands (d) foramina Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins