Chapter 12

Skin: Integumentary System

Related Combining Forms

Structure

Related Combining Forms

Skin

cutane/o, dermat/o, derm/o

Sebaceous glands

seb/o

Sweat glands

hidr/o

Hair

pil/i, pil/o

Nails

onych/o, ungu/o

Integumentary System

• Consists of skin and its related structures (sebaceous glands, sweat glands, hair, and nails) • Average adult has two square yards of skin, making it the largest body organ

Functions of Skin

• Keeps the body waterproof, hence preventing fluid loss • When intact, skin blocks the entrance of pathogens • Contains receptors for the sense of touch • Synthesizes vitamin D from the sun

Functions of Related Structures

• Sebaceous glands – Secrete sebum that lubricates skin and discourages growth of bacteria on skin

• Sweat glands – Assist with body water content and temperature regulation – Excretion of small amounts of metabolic wastes

Functions of Related Structures

• Hair – Helps control the loss of body heat

• Nails – Protect dorsal surface of last bone of each toe and finger

Structures of Skin and Its Related Structures

• Skin – Specialized tissues – Three layers • Epidermis • Dermis • Subcutaneous – (cutane: skin; -ous: pertaining to)

Structures of Skin and Its Related Structures

Epidermis

– (epi-: above or upon; derm: skin; -is: noun ending)

• Outermost layer of skin • Made of specialized epithelial tissues • Contains no blood vessels or connective tissue • Depends on the lower layers for nourishment

Epidermis

• Epithelial tissues – Form protective covering for internal and external surfaces of the body

• Squamous epithelial tissue – Forms upper layer of epidermis – Flat, scaly cells continuously shed

Epidermis

• Basal layer – Lowest layer of epidermis – Site of new cell production – When cells reach surface, they die and become filled with keratin

• Keratin – Fibrous, water-repellent protein • Soft keratin: component of epidermis • Hard keratin: found in hair and nails

Epidermis

• Melanocytes – Special cells in basal cell layer – Produce and contain dark brown to black pigment known as melanin

• Melanin – Pigment that determines color of skin, produces freckles and age spots – Protects skin from some of the harmful UV rays

Dermis

• Directly below epidermis • Contains connective tissue, blood and lymph vessels, nerve fibers, hair follicles, sebaceous glands, and sweat glands • Sensory nerve endings – Sensory receptors for touch, temperature, pain, and pressure

Tissues Within Dermis

• Collagen – Tough flexible fibrous protein found in skin, bones, cartilage, tendons, and ligaments

• Mast cells – Found in connective tissue of dermis – Respond to injury, infection, or allergy by producing and releasing heparin (anticoagulant) and histamine (causes allergic response)

Subcutaneous Layer

• Located below the layers of skin • Connects skin to the surface muscles • Made of loose connective tissue and adipose tissue • Lipocytes manufacture and store large quantities of fat – (lip/o: fat; -cytes: cells)

Sebaceous Glands

• Located in dermis • Closely associated with hair follicles • Sebum – Oily substance released through ducts opening into hair follicles – Lubricates skin – Acidic, thus discourages growth of bacteria on skin

Sebaceous Glands

• Mammary glands – Produce milk – Also part of the reproductive system

Sweat Glands

• Sudoriferous glands • Located on almost all body surfaces • Two types – Apocrine • Found at hair follicles

– Eccrine • Open onto skin • Most numerous in palms, soles, and forehead

Sweat Glands

• Pores – Opening on the surface of skin – Act as ducts of the sweat glands

• Perspiration – Secreted by sweat glands – 99% water plus salt and metabolic waste – Evaporation of sweat cools the body

Sweat Glands

• Hidrosis – Production and excretion of perspiration

Hair

• Composed of dead protein cells filled with hard keratin • Color of hair determined by melanin • Hair follicles – Sacs holding the root of hair fibers

• Arrector pili – Muscle fibers attached to hair follicles that cause hair to stand erect, reducing heat loss

Nails

• Unguis (fingernail or toenail) • Keratin plate protecting dorsal surface of the last bone of each finger and toe • Nail body – Translucent – Molded to surface of underlying tissues – Make of hard, keratinized plates of epidermal cells

Nails

Nails

• Nail bed – Joins nail body to underlying connective tissue – Nourishes the nail – Blood vessels provide pink color

• Free edge – Portion of nail not attached to the nail bed – Extends beyond tip of the finger or toe

Nails

• Lunula – Half-moon-shaped region at nail root – Site of new keratin cell formation • (lun: moon; -ula: little)

• Cuticle – Epidermis attached to the surface of nail

• Nail root – Fastens nail to finger/toe

Medical Specialties Related to Integumentary System

• Dermatologist – Specializes in diagnosing/treating disorders of the skin • (dermat: skin; -ologist: specialist)

• Plastic surgeon – Specializes in surgical restoration or reconstruction of body structures • (-plasty: surgical repair)

Medical Specialties Related to Integumentary System

• Cosmetic surgeon – Plastic surgeon who performs operations for aesthetic rather than medical reasons

Pathology of Integumentary System

• Sebaceous Glands – Acne vulgaris • Chronic inflammatory disease caused by the overproduction of sebum around the hair shaft

– Comedo • Noninfected lesion composed of sebum and keratin in hair follicle • Closed comedo: whitehead • Open comedo: blackhead

Sebaceous Glands

– Epidermoid cyst • Closed sac just under the skin • Contains fatty material

– Seborrhea • Overproduction of sebum • (seb/o: sebum; -rrhea: flow or discharge)

Sebaceous Glands

– Seborrheic dermatitis • Inflammation causing scaling/itching of upper layers of skin/scalp

– Seborrheic keratosis • Benign skin growth having a waxy appearance • Varied colors • Common in elderly

Sweat Glands

– Anhidrosis • Condition of lacking sweat in response to heat – (an-: without; hidr: sweat; -osis: abnormal condition)

– Diaphoresis • Profuse sweating – (dia-: through or complete; phor: movement; -esis: abnormal condition)

– Heat rash • Itchy rash related to the blockage of sweat glands by bacteria and dead cells

Sweat Glands

– Hyperhidrosis • Excessive sweating in one area or over the whole body – (hyper-: excessive; hidr: sweat; -osis: abnormal condition)

– Sleep hyperhidrosis • Hyperhidrosis during sleep

Hair

– Folliculitis • Inflammation of hair follicles – (follicul: hair follicle; -itis: inflammation)

– Trichomycosis axillaris • Superficial bacterial infection of hair shafts in areas with extensive sweat glands, such as armpits – (trich/o: hair; myc: fungus; -osis: abnormal condition; axill: armpit; -ary: pertaining to)

Excessive Hairiness

– Hirsutism • Excessive body and facial hair in women, usually occurring in a male pattern – (hirsut: hairy; -ism: condition)

Abnormal Hair Loss

– Alopecia • Partial or complete loss of hair – (alopec: baldness; -ia: condition)

– Alopecia areata • Autoimmune disorder attacking hair follicles • Occurs in patches on scalp or elsewhere on body

Abnormal Hair Loss

– Alopecia totalis • Loss of all hair on the scalp

– Alopecia universalis • Total loss of hair on all parts of the body

– Androgenic alopecia • Hair loss due to hormonal changes • Occurs in males and females

Nails

– Clubbing • • • •

Abnormal curving of nails Often accompanied by enlargement of fingertips May be hereditary May be due to changes associated with oxygen deficiencies related to coronary or pulmonary disease

Nails

– Koilonychia • Outer surface of nail is concave • Often indicates iron-deficiency anemia – (koil: hollow or concave; onych: fingernail or toenail; -ia: condition)

– Onychia • Inflammation of matrix of nail • May result in the loss of nail

Nails

– Onychocryptosis • Edges of toenail curve inward and cut into the skin – (onych/o: fingernail or toenail; crypt: hidden; -osis: abnormal condition)

– Onychomycosis • Fungal infection of nail – (myc: fungus)

– Paronychia • Infection of skin fold around a nail – (par-: near)

Skin Pigmentation

• Acanthosis nigricans – Development of dark wart-like patches on one or more areas of skin

• Age spots – Discoloration caused by sun exposure

• Albinism – Genetic condition characterized by lack of pigment in skin, hair, and irises of eyes • (albin: white)

Skin Pigmentation

• Chloasma – Brownish spots on face – May occur during pregnancy, and disappear after delivery of infant

• Vitiligo – Irregular patches of white skin related to destruction of melanocytes

Bleeding into Skin

• Contusion – Injury to underlying tissues without breaking the skin – Discoloration caused by accumulation of blood within the skin • (contus: bruise; -ion: condition)

Bleeding into Skin

• Ecchymosis – Large, irregular purplish discoloration due to bleeding under the skin • (ecchym: pouring out of juice; -osis: abnormal condition)

• Purpura – Multiple purple discoloration on skin due to bleeding underneath the skin • (purpur: purple; -a: noun ending)

Bleeding into Skin

Bleeding into Skin

• Petechiae – Small, pinpoint hemorrhages less than 2 mm in diameter

• Hematoma – Usually due to injury – Swelling of clotted blood trapped in tissues – Blood is reabsorbed • (hemat: blood; -oma: tumor)

Surface Lesions

• Crust – Collection of dried serum and cellular debris

• Erosion – Wearing away of a surface

• Macule – Flat, discolored spot less than 1 cm in diameter

Surface Lesions

Surface Lesions

• Nodule – Solid, raised skin lesion larger than 0.5 cm in diameter

• Papule – Raised, red lesion less than 0.5 cm in diameter – Does not contain pus

Surface Lesions

• Plaque – Scaly, solid raised area of closely spaced papules

• Scales – Flakes or dry patches of excess dead epidermal cells – Some shedding is normal – Excessive shedding associated with the skin disorders

Surface Lesions

• Verrucae – Small, hard skin lesions caused by human papillomavirus – Also known as warts

• Wheal – Small, itchy bump – May be due to an allergic reaction

Fluid-Filled Lesions

• Abscess – Closed pocket containing pus – Due to bacterial infection

• Purulent – Producing or containing pus

• Exudate – Fluid leaking out of an infected wound

Fluid-Filled Lesions

• Cyst – Abnormal sac containing fluid, or semisolid material

• Pustule – Small, circumscribed lesion containing pus – Contained within a limited area

Fluid-Filled Lesions

Fluid-Filled Lesions

• Vesicle – Blister, less than 0.5 cm in diameter – Contains watery fluid

• Bulla – Large blister more than 0.5 cm in diameter

Lesions Through Skin

• Abrasion – Superficial layers are scraped away

• Fissure – Crack-like break in the skin

• Laceration – Torn or jagged wound

Lesions Through Skin

Lesions Through Skin

• Pressure sore – Open ulcerated wound caused by the prolonged pressure on an area of the skin

• Needlestick injury – Accidental puncture wound caused by hypodermic needle

• Ulcer – Open lesion resulting in tissue loss around the edges

Birthmarks

• Pigmented birthmarks – Also known as moles or café-au-lait spots

• Vascular birthmarks – Caused by blood vessels close to the skin's surface

Birthmarks

• Capillary hemangioma – Soft, raised, pink or red vascular birthmark – Benign tissue mass • (hem: blood; angi: blood or lymph vessels; -oma: tumor)

• Port-wine stain – Flat vascular birthmark made up of dilated blood capillaries – Creates reddish-purple discoloration

Dermatitis

• Inflammation of the skin • Contact dermatitis – Localized allergic response • (dermat: skin; -itis: inflammation)

• Eczema – Recurring dermatitis characterized by redness, itching, and dryness

Dermatitis

• Exfoliative dermatitis – Widespread scaling of the skin

• Pruritus – Itching associated with the most forms of dermatitis • (prurit: itching)

Erythema

• Redness of skin due to capillary dilation – (erythem: flushed; -a: noun ending)

• Erythema infectiosum – Mildly contagious viral infection common in children – Also known as fifth disease

Erythema

• Erythema multiforme – Generalized allergic reaction to illness, infection, or medication

• Erythema pernio – Purple-red inflammation occurring when small blood vessels below the skin are damaged

Erythema

• Erythroderma – Abnormal redness of entire skin surface • (erythr/o: red; -derma: skin)

• Exanthem – Widespread rash

• Hand, foot, and mouth disease – Mild viral infection common in children under 5 years of age – Sores in mouth/throat; rash on hands/feet

General Skin Conditions

• Dermatosis – Denotes skin lesion or eruption of any type not associated with inflammation

• Ichthyosis – Hereditary disorders characterized by dry, thickened, scaly skin • (ichthy: dry or scaly; -osis: abnormal condition)

General Skin Conditions

• Lipedema – Characterized by accumulation of fat and fluid in tissues under the skin of hips and legs • (lip: fat; -edema: swelling)

• Systemic lupus erythematosus – Autoimmune disorder characterized by red, scaly rash on face/upper trunk

• Psoriasis – Occurrence of red papules with silvery scales

General Skin Conditions

• Roseacea – Tiny red pimples and broken blood vessels – Commonly seen in adults 30–60 years of age

• Rhinophyma – Hyperplasia of tissues of nose – Usually seen in older men • (rhin/o: nose; -phyma: growth)

General Skin Conditions

• Scleroderma – Autoimmune disorder in which connective tissues become thickened and hardened • (scler/o: hard; -derma: skin)

• Urticaria – Itchy wheals due to allergic reaction • (urtic: rash; -aria: connected with)

General Skin Conditions

• Xeroderma – Excessively dry skin • (xer/o: dry; -derma: skin)

Bacterial Skin Infections

• Carbuncle – Cluster of furuncles

• Cellulitis – Acute bacterial infection within connective tissues – Characterized by malaise, swelling, warmth, and red streaks

Bacterial Skin Infections

• Furuncles – Large, tender, swollen areas caused by staphylococcal infection around hair follicles or sebaceous glands

• Gangrene – Death of tissue, followed by bacterial invasion, which may also enter bloodstream – Commonly due to the loss of circulation to the affected tissues

Bacterial Skin Infections

• Impetigo – Highly contagious bacterial skin infection – Common in children

• Necrotizing fasciitis – Caused by Group A strep that enters the body through a skin wound

Bacterial Skin Infections

• Pyoderma – Acute, pus-forming bacterial skin infection • (py/o: pus; -derma: skin)

Fungal Skin Infections

• Mycosis – Abnormal condition caused by fungus • (myc: fungus; -osis: abnormal condition)

• Tinea – Fungal infection on skin, hair, or nails – Known as ringworm

Parasitic Skin Infestations

• Pediculosis – Infestation with lice • (pedicul: lice; -osis: abnormal condition)

• Scabies – Skin infection caused by itch mites

Skin Growths

• Callus – Thickening of the part of the skin caused by repeated rubbing

• Cicatrix – Normal scar

• Granulation tissue – Forms during healing of a wound

Skin Growths

• Granuloma – Small swelling of granulation tissue – May result from inflammation, injury, infection • (granul: granular; -oma: tumor)

• Keloid – Thickened scar expanding beyond the boundaries of original incision • (kel: growth or tumor; -oid: resembling)

Skin Growths

• Keratosis – Overgrowth and thickening of the skin • (kerat: hard or horny)

• Lipoma – Benign fatty tumor located between the skin and muscle layer

• Nevus – Small, dark skin growth developing from melanocytes

Skin Growths

• Dysplastic nevi – Atypical moles – May develop into skin cancer

• Papilloma – Benign wart-like growth on epithelial tissue or elsewhere in the body • (papill: resembling a nipple; -oma: tumor)

Skin Growths

• Polyp – Mushroom-like growth from the surface of mucous membrane

• Skin tags – Flesh-colored polyps hanging from the body by fine stalks – Benign – Tend to enlarge with age

Skin Cancers

• Malignant growth on skin • Three types – Basal cell carcinoma – Squamous cell carcinoma – Melanoma

Skin Cancers

• Actinic keratosis – Precancerous skin growth occurring on sundamaged skin – Lack of treatment may lead to cancer

• Basal cell carcinoma – Malignant tumor of basal cell layer of epidermis – Rarely spreads

Skin Cancers

• Squamous cell carcinoma – Malignant tumor of squamous cells of epithelium – Can spread quickly to other body systems

• Malignant melanoma – Occurs in melanocytes – Initial symptoms are change in the size, shape, or color of a mole • (melan: black; -oma: tumor)

Burns

• Injury caused by heat, flame, electricity, sun, chemicals, or radiation • Severity described according to the percentage of the total body skin surface affected or by depth or layer of skin involved

Diagnostic Procedures of Integumentary System

• Biopsy – Removal of small piece of living tissue for confirmation of diagnosis • (bi: pertaining to life; -opsy: view of)

• Exfoliative cytology – Cells are scraped from tissue for microscopic examination

Treatment Procedures of Integumentary System

• Preventive measures – Sunscreen • Blocks harmful ultraviolet B (UVB) rays or ultraviolet A (UVA) rays • Measured in terms of strength of sun protection factor (SPF)

Burn Treatment

– Depends on degree of burn, and percentage of the body surface involved – Burn centers provide pain relief, debridement, dermoplasty, IV fluids and nutritional supplements, antibiotics, cosmetic reconstruction, and rehabilitation

Tissue Removal

– Cauterization • Destruction of tissue by burning

– Chemabrasion • Use of chemicals to remove outer layers of skin

– Cryosurgery • Destruction or elimination of abnormal tissue cells – (cry/o: cold; -surgery: operative procedure)

Tissue Removal

– Curettage • Removal of surface material by scraping

– Debridement • Removal of dirt, foreign objects, damaged tissue, and cellular debris from a wound • Prevention of infection and promotion of healing

– Irrigation and debridement • Pressurized fluid to clean wound debris

Tissue Removal

– Dermabrasion • Involves use of revolving wire brush or sandpaper

– Electrodesiccation • Destruction of tissue by the use of electric spark

– Incision • Use of surgical instrument to cut open a lesion

Tissue Removal

– Mohs' surgery • Layers of cancerous tissue are removed and examined under the microscope • Procedure is repeated until margin that is clear of all cancerous tissue is achieved

Laser and Light Source Treatments of Skin Conditions

• Laser (Light Amplification by Stimulated Emission of Radiation) – Laser tube filled with solid, liquid, or gas substance is stimulated to emit light at a specific wavelength

• Photosensitizing drug – Administered topically or by injection – After activation, drugs produce a form of oxygen that kills nearby cells

Medications for Treatment of Skin

• Retinoids – Derived from vitamin A and are used because of their effect on epithelial cell growth

• Topical steroids – Derivatives of natural corticosteroid hormones – Treatment of various skin disorders

Cosmetic Procedures

• Blepharoplasty – Surgical reduction of upper and lower eyelids by removing sagging skin • (blephar/o: eyelid; -plasty: surgical repair)

• Botox – Used to reduce moderate-to-severe frown lines, to treat migraines and muscle spasms

• Collagen replacement therapy – Used for soft-tissue augmentation

Cosmetic Procedures

• Dermatoplasty – Replacement of damaged skin of a patient with the healthy tissue taken from a donor site

• Electrolysis – Use of electric current to destroy hair follicles

• Lipectomy – Surgical removal of fat from beneath the skin to improve physical appearance

Cosmetic Procedures

• Liposuction – Surgical removal of fat beneath the skin with the aid of suction

• Rhytidectomy – Surgical removal of excess skin and fat from the face • (rhytid: wrinkle; -ectomy: surgical removal)

Cosmetic Procedures

• Sclerotherapy – Injection of a saline sclerosing solution for treatment of spider veins (nonessential veins seen through the skin)