Skin: The Integumentary System
A dermatologist (der-mah-TOL-oh-jist) iA comedo (KOM-eh-doh) is a noninfected lesion formed by the buildup of sebum and keratin in a hair follicle often associated with acne vulgaris (plural, comedones).
- A plastic surgeon is a physician who specializes in the surgical restoration and reconstruction of body structures. The term plastic is related to the suffix -plasty, meaning surgical repair. - Cosmetic surgeons are plastic surgeons who perform operations such as breast augmentation, liposuction, and facelifts that are usually done for aesthetic rather than medical reasons.
Perspiration, commonly known as sweat, is secreted by sweat glands and is made up of 99% water plus some salt and metabolic waste products.
- Perspiring is one way in which the body excretes excess water. Normally, up to one quart of liquid is perspired daily. - As the perspiration evaporates into the air, it also cools the body. Body odor associated with perspiration comes from the interaction of sweat with bacteria on the skin's surface.
The lunula (LOO-new-lah) is a pale half-moon-shaped region at every nail root, which is generally most easily seen in the thumbnail (plural, lunulae). This is the active area of the nail, where new keratin cells form ( lun means moon, and -ula means little).
- The cuticle is a narrow band of epidermis attached to the surface of the nail just in front of the root, protecting the new keratin cells as they form. - The nail root fastens the nail to the finger or toe by fitting into a groove in the skin.
An unguis (UNG-gwis), which is commonly known as a fingernail or toenail, is the keratin plate that protects the dorsal surface of the last bone of each finger and toe (plural, ungues). Each nail consists of the following parts (Figure 12.3):
- The nail body, which is translucent, is closely molded to the surface of the underlying tissues. It is made up of hard, keratinized plates of epidermal cells.
Photodynamic therapy (foh-toh-dye-NAH-mik) (PDT) is a technique used to treat damaged and precancerous skin, as well as various types of cancer.
-A photosensitizing drug is administered topically or by injection. An incubation period is followed by exposure to a specific wavelength of light, administered either externally or endoscopically. -When the photosensitizers are thus activated, they produce a form of oxygen that kills nearby cells. PDT is used to treat tumors on or near the surface of the skin, or in the lining of internal organs such as the lungs and esophagus.
A biopsy (BYE-op-see) is the removal of a small piece of living tissue for examination to confirm or establish a diagnosis ( bi means pertaining to life, and -opsy means view of).
-In an incisional biopsy, a piece, but not all, of the tumor or lesion is removed. -In an excisional biopsy, the entire tumor or lesion and a margin of surrounding tissue are removed. Excision means the complete removal of a lesion or organ. -In a needle biopsy, a hollow needle is used to remove a core of tissue for examination.
Retinoids (RET-ih-noydz) are a class of chemical compounds derived from vitamin A that are used in skin care and treatment because of their effect on epithelial cell growth. The use of retinoids can, however, make the skin burn more easily.
-Isotretinoin, known by its trade name of Accutane, is a powerful retinoid taken in pill form for the treatment of severe acne. -Tretinoin is the active ingredient in Retin-A and Renova, which are used to treat sun-damaged skin, acne, and wrinkles.
A laser tube can be filled with a solid, liquid, or gas substance that is stimulated to emit light at a specific wavelength. Some wavelengths are capable of destroying all skin tissue; others target tissue of a particular color.
-Port-wine stain is treated using short pulses of laser light to remove the birthmark. Treatment can require many sessions because only a small section is treated at a time. -Rhinophyma is treated by using a laser to reshape the nose by vaporizing the excess tissue. -Tattoos are removed by using lasers that target particular colors. -Some skin cancers, precancer of the lip, and warts that recur around nails and on the soles of feet are treated using lasers.
-Tinea capitis is found on the scalps of children. Capitis means head. -Tinea corporis is a fungal infection of the skin on the body. Corporis means body. -Tinea cruris, also known as jock itch, is found in the genital area.
-Tinea pedis, also known as athlete's foot, is most commonly found between the toes. Pedis means feet. -Tinea versicolor, also known as pityriasis versicolor, is a fungal infection that causes painless, discolored areas on the skin. Versicolor means a variety of color.
An ulcer (UL-ser) is an open lesion of the skin or mucous membrane resulting in tissue loss around the edges (Figure 12.8B). Note: Ulcers also occur inside the body. Those associated with the digestive system are discussed in Chapter 8.
A birthmark is a mole or blemish on the skin present at birth or shortly thereafter. Some birthmarks fade as a child gets older.
Malignant melanoma (mel-ah-NOH-mah) (MM), also known as melanoma, is a type of skin cancer that occurs in the melanocytes ( melan means black, and -oma means tumor). This is the most serious type of skin cancer, and often the first signs are changes in the size, shape, or color of a mole. One way to remember this is by thinking of A-B-C-D-E: Asymmetry, Border irregularity, Color variation, Diameter larger than a pencil eraser, and Evolving by changing in size, shape, shade, or color (Figure 12.14).
A burn is an injury to body tissues caused by heat, flame, electricity, sun, chemicals, or radiation. The severity of a burn is described according to the percentage of the total body skin surface affected (more than 15% is considered serious). It is also described according to the depth or layers of skin involved (Table 12.1 and Figure 12.15).
Xeroderma (zee-roh-DER-mah), also known as xerosis, is excessively dry skin ( xer/o means dry, and -derma means skin).
A carbuncle (KAR-bung-kul) is a cluster of connected furuncles (boils).
A callus (KAL-us) is a thickening of part of the skin on the hands or feet caused by repeated rubbing. Compare with callus in Chapter 3. A clavus, or corn, is a callus in the keratin layer of the skin covering the joints of the toes, usually caused by ill-fitting shoes.
A cicatrix (sick-AY-tricks) is a normal scar resulting from the healing of a wound (plural, cicatrices).
Acne vulgaris (ACK-nee vul-GAY-ris), commonly known as acne, is a chronic inflammatory disease characterized by pustular eruptions of the skin caused by an overproduction of sebum around the hair shaft. Although often triggered by hormones in puberty and adolescence, it also occurs in adults. Vulgaris is a Latin term meaning common.
A comedo (KOM-eh-doh) is a noninfected lesion formed by the buildup of sebum and keratin in a hair follicle often associated with acne vulgaris (plural, comedones). A comedo with an obstructed opening is called a whitehead (a closed comedo). A sebum plug that is exposed to air often oxidizes and becomes a blackhead (an open comedo).
Vitiligo (vit-ih-LYE-goh) is a skin condition resulting from the destruction of the melanocytes due to unknown causes. Vitiligo causes irregular patches of white skin, a process known as depigmentation. Hair growing in an affected area may also turn white.
A contusion (kon-TOO-zhun) is an injury to underlying tissues without breaking the skin and is characterized by discoloration and pain ( contus means bruise, and -ion means condition). This discoloration is caused by an accumulation of blood within the skin.
A lesion (LEE-zhun) is a pathologic change of the tissues due to disease or injury. Skin lesions are described by their appearance, location, color, and size as measured in centimeters (cm).
A crust, also known as scab, is a collection of dried serum and cellular debris (Figure 12.6A).
An exudate (ECKS-you-dayt) is a fluid, such as pus, that leaks out of an infected wound.
A cyst (SIST) is an abnormal sac containing gas, fluid, or a semisolid material (Figure 12.7A). The term cyst can also refer to a sac or vesicle elsewhere in the body. The most common type of skin cyst is a sebaceous cyst.
Petechiae (pee-TEE-kee-ee) are very small, pinpoint hemorrhages that are less than 2 mm in diameter (singular, petechia). These hemorrhages sometimes result from high fevers.
A hematoma (hee-mah-TOH-mah), which is usually caused by an injury, is a swelling of clotted blood trapped in the tissues ( hemat means blood, and -oma means tumor). The body eventually reabsorbs this blood. A hematoma is often named for the area where it occurs. For example, a subungual hematoma is blood trapped under a finger or toenail.
A keloid (KEE-loid) is an abnormally raised or thickened scar that expands beyond the boundaries of the original incision ( kel means growth or tumor, and -oid means resembling). A tendency to form keloids is often inherited and is more common among people with dark-pigmented skin.
A keratosis (kerr-ah-TOH-sis) is any skin growth, such as a wart or a callus, in which there is overgrowth and thickening of the skin ( kerat means hard or horny, and -osis means abnormal condition) (plural, keratoses). Patches of keratosis in the mouth are known as leukoplakia. Note: kerat/o also refers to the cornea of the eye (see Chapter 11).
A fissure (FISH-ur) is a groove or crack-like break in the skin. Fissures are, for example, the breaks in the skin between the toes caused by tinea pedis, or athlete's foot (Figure 12.8A). The term fissure also describes folds in the contours of the brain.
A laceration (lass-er-AY-shun) is a torn or jagged wound or an accidental cut wound.
Erosion (eh-ROH-zhun) is the wearing away of a surface, such as the epidermis of the skin or the outer layer of a mucous membrane. This term can also describe the progressive loss of dental enamel.
A macule (MACK-youl), also known as a macula, is a discolored flat spot that is less than 1 cm in diameter. Freckles, or flat moles, are examples of macules (Figure 12.6B).
A pressure sore, previously known as a decubitus ulcer or bedsore, is an open ulcerated wound that is caused by prolonged pressure on an area of skin. Without proper care, these sores quickly become seriously infected and can result in tissue death.
A needlestick injury is an accidental puncture wound caused by a used hypodermic needle, potentially transmitting an infection. A puncture wound is an injury caused by a pointed object piercing the skin.
In contrast, dysplastic nevi (dis-PLAS-tick NEE-vye) are atypical moles that can develop into skin cancer.
A papilloma (pap-ih-LOH-mah) is a benign, superficial, wart-like growth on the epithelial tissue or elsewhere in the body, such as in the bladder ( papill means resembling a nipple, and -oma means tumor).
A nodule (NOD-youl) is a solid, raised skin lesion that is larger than 0.5 cm in diameter and deeper than a papule. In acne vulgaris, nodules can cause scarring.
A papule (PAP-youl) is a small, raised red lesion that is less than 0.5 cm in diameter and does not contain pus. Small pimples and insect bites are types of papules (Figure 12.6C).
A capillary hemangioma (KAP-uh-ler-ee hee-man-jee-OH-mah), also known as a strawberry birthmark, is a soft, raised, pink or red vascular birthmark ( hem means blood, angi means blood or lymph vessels, and -oma means tumor). A hemangioma is a benign tissue mass made up of newly formed small blood vessels that in birthmarks are visible through the skin (Figure 12.9). (Also see hemangioma in Chapter 5.)
A port-wine stain is a flat vascular birthmark made up of dilated blood capillaries, creating a large, reddish-purple discoloration on the face or neck. This type of birthmark will not resolve without treatment. See the later section "Laser and Light Source Treatments of Skin Conditions."
Seborrheic dermatitis (seb-oh-REE-ick der-mah-TYE-tis) is an inflammation sometimes resulting from seborrhea that causes scaling and itching of the upper layers of the skin or scalp. Extensive dandruff is a form of seborrheic dermatitis, as is the scalp rash in infants known as cradle cap. In contrast, mild dandruff is usually caused by a yeast-like fungus on the scalp.
A seborrheic keratosis (seb-oh-REE-ick kerr-ah-TOH-sis) is a benign skin growth that has a waxy or "pasted-on" look. These growths, which can vary in color from light tan to black, occur most commonly in the elderly.
A pustule (PUS-tyoul), also known as a pimple, is a small, circumscribed lesion containing pus (Figure 12.7B). Circumscribed means contained within a limited area. Pustules can be caused by acne vulgaris, impetigo, or other skin infections.
A vesicle (VES-ih-kul) is a small blister, less than 0.5 cm in diameter, containing watery fluid (Figure 12.7C). For example, the rash of poison ivy consists of vesicles (Figure 12.10).
Verrucae (veh-ROO-kee), also known as warts, are small, hard skin lesions caused by the human papillomavirus (singular, verruca). Plantar warts are verrucae that develop on the sole of the foot. See Chapter 14 for more information on the human papillomavirus.
A wheal (WHEEL), also known as a welt, is a small bump that itches. Wheals can appear as urticaria, or hives, as a symptom of an allergic reaction (Figure 12.6D).
Acanthosis nigricans (ak-an-THO-sis NIG-rih-kans) is a condition where one or more areas of the skin develop dark, wart-like patches. This can be a sign of a disease such as cancer or type 2 diabetes or a reaction to a medication.
Age spots, also known as solar lentigines or liver spots, are discolorations caused by sun exposure. Although harmless, these spots sometimes resemble skin cancer growths.
Alopecia (al-oh-PEE-shee-ah), also known as baldness, is the partial or complete loss of hair, most commonly on the scalp ( alopec means baldness, and -ia means condition).
Alopecia areata (ah-ree-AY-tuh) is an autoimmune disorder that attacks the hair follicles, causing well-defined bald areas on the scalp or elsewhere on the body (Figure 12.4). This condition often begins in childhood. Areata means occurring in patches.
Androgenic alopecia (an-DROH-jen-ik al-oh-PEE-shee-ah) is the most common type of hair loss. Androgenic means referring to androgens, the hormones involved in the development and maintenance of masculine characteristics (see Chapter 13).
Alopecia totalis (toh-TAL-is) (AT) is an uncommon condition characterized by the loss of all the hair on the scalp.
In men it is called male pattern baldness, with the hairline receding from the front to the back until only a horseshoe-shaped area of hair remains in the back and at the temples. When it occurs in women it is called female pattern baldness, and is characterized by the hair thinning in the front and on the sides of the scalp and sometimes on the crown. This condition rarely leads to total hair loss.
Alopecia universalis (yoo-nih-vers-AHL-is) (AU) is the total loss of hair on all parts of the body. Universalis means total.
A bulla (BULL-ah) is a large blister that is usually more than 0.5 cm in diameter (plural, bullae) (Figure 12.7D).
An abrasion (ah-BRAY-zhun) is an injury in which superficial layers of skin are scraped or rubbed away.
Skin cancer is a malignant growth on the skin which can have many causes, including repeated severe sunburns or long-term exposure to the sun. Skin cancer is becoming very common, affecting about one in five Americans in his or her lifetime. There are three main types of skin cancer: basal cell carcinoma, squamous cell carcinoma, and melanoma.
An actinic keratosis (ack-TIN-ick kerr-ah-TOH-sis), also called a solar keratosis, is a precancerous skin growth that occurs on sun-damaged skin. It often looks like a red, tan, or pink scaly patch and feels like sandpaper. Precancerous describes a growth that is not yet malignant; however, if not treated, it is likely to become malignant.
Electrodesiccation (ee-leck-troh-des-ih-KAY-shun) is a surgical technique in which tissue is destroyed using an electric spark. It is primarily used to eliminate small superficial growths and to seal off blood vessels.
An incision is a cut made with a surgical instrument. Incision and drainage (I & D) in an incision (cutting open) of a lesion, such as an abscess, and the draining of the contents.
Blepharoplasty (BLEF-ah-roh-plas-tee), also known as a lid lift, is the surgical reduction of the upper and lower eyelids by removing sagging skin ( blephar/o means eyelid, and -plasty means surgical repair) (Figure 12.16). A small amount of fat from the patient's thighs or buttocks is sometimes injected in the hollow below the eye to improve appearance.
Botox is a formulation of botulinum toxin. This is the same neurotoxin responsible for the form of food poisoning known as botulism. When small, sterile doses are injected into muscles on the forehead, it can temporarily block the nerve signals to the injected muscle for up to 3 to 4 months, reducing moderate to severe frown lines between the eyebrows. Botox is also used therapeutically to treat migraines, overactive bladder, strabismus, and muscle spasms.
The type of treatment for a burn depends on its degree and the percentage of the body surface involved. A hospital burn center provides care for serious burns, including pain relief, debridement and dermoplasty (skin grafts), IV fluids and nutritional supplements, antibiotics, cosmetic reconstruction, and rehabilitation.
Cauterization (kaw-ter-eye-ZAY-shun) is the destruction of tissue by burning.
Albinism (AL-bih-niz-um) is a genetic condition characterized by a deficiency or the absence of pigment in the skin, hair, and irises of the eyes ( albin means white, and -ism means condition). This condition is the result of a missing enzyme that is necessary for the production of melanin. A person with this condition is known as an albino.
Chloasma (kloh-AZ-mah), also known as melasma or the mask of pregnancy, is a pigmentation disorder characterized by brownish spots on the face. This can occur during pregnancy, especially among women with dark hair and fair skin, and usually disappears after delivery.
The term dermatitis (der-mah-TYE-tis) describes an inflammation of the skin ( dermat means skin, and -itis means inflammation). This condition, which takes many forms, is usually characterized by redness, swelling, and itching.
Contact dermatitis (CD) is a localized allergic response caused by contact with an irritant, such as diaper rash. It can also be caused by exposure to an allergen, such as poison ivy, or an allergic reaction to latex gloves (Figure 12.10).
Chemabrasion (kem-ah-BRAY-zhun) also known as a chemical peel, is the use of chemicals to remove the outer layers of skin to treat acne scarring, fine wrinkling, and keratoses.
Cryosurgery (krye-oh-SIR-jur-ee), also called freezing, is the destruction or elimination of abnormal tissue cells, such as warts or tumors, through the application of extreme cold by using liquid nitrogen ( cry/o means cold, and -surgery means operative procedure).
Curettage (kyou-reh-TAHZH) is the removal of material from the surface by scraping. One use of this technique is to remove basal cell tumors.
Debridement (dah-BREED-ment) is the removal of dirt, foreign objects, damaged tissue, and cellular debris from a wound to prevent infection and to promote healing.
In an irrigation and debridement (I & D) procedure, pressurized fluid is used to clean out wound debris.
Dermabrasion (der-mah-BRAY-zhun) is a form of abrasion involving the use of a revolving wire brush or sandpaper. It is used to remove acne and chickenpox scars as well as for facial skin rejuvenation. Microdermabrasion removes only a fine layer of skin, so the results are temporary.
Collagen replacement therapy is a form of soft-tissue augmentation used to soften facial lines or scars or to make lips appear fuller. Tiny quantities of collagen are injected under a line or scar to boost the skin's natural supply of collagen. The effect usually lasts for 3 to 12 months.
Dermatoplasty (DER-mah-toh-plas-tee), also known as a skin graft, is the replacement of damaged skin with healthy tissue taken from a donor site on the patient's body ( dermat/o means skin, and -plasty means surgical repair).
Hand, foot, and mouth disease is a mild viral infection common in children under 5 years of age. It is characterized by sores in the mouth and throat and a rash on the hands and feet.
Dermatosis (der-mah-TOH-sis) is a general term used to denote skin lesions or eruptions of any type that are not associated with inflammation ( dermat means skin, and -osis means abnormal condition).
Anhidrosis (an-high-DROH-sis) is the abnormal condition of lacking sweat in response to heat ( an- means without, hidr means sweat, and -osis means abnormal condition).
Diaphoresis (dye-ah-foh-REE-sis) is profuse sweating ( dia- means through or complete, phor means movement, and -esis means abnormal condition). This is a normal condition when brought on by heat or exertion but can also be the body's response to emotional or physical distress.
Pruritus (proo-RYE-tus), also known as itching, is associated with most forms of dermatitis ( prurit means itching, and -us is a singular noun ending). Note that this term ends in -us, not -is.
Erythema (er-ih-THEE-mah) is redness of the skin due to capillary dilation ( erythem means flushed, and -a is a noun ending). Dilation describes the expansion of the capillary.
Erythema infectiosum, also known as fifth disease, is a mildly contagious viral infection that is common in childhood. This infection produces a red, lace-like rash on the child's face that looks as if the child has been slapped. It is called "fifth disease" for its place on a list of six common childhood diseases that can cause an exanthem (widespread rash). Others include measles and rubella.
Erythema multiforme is a skin disorder resulting from a generalized allergic reaction to an illness, infection, or medication. This reaction, which affects the skin, the mucous membranes, or both, is characterized by a rash that may appear as nodules or papules (raised red bumps), macules (flat discolored areas), or vesicles or bullae (blisters).
Erythroderma (eh-rith-roh-DER-mah) is abnormal redness of the entire skin surface ( erythr/o means red, and -derma means skin).
Exanthem (eck-ZAN-thum) refers to a widespread rash, usually in children. A rash is a breaking out, or eruption, that changes the color or texture of the skin.
Eczema (ECK-zeh-mah), also known as atopic dermatitis, is a form of persistent or recurring dermatitis usually characterized by redness, itching, and dryness, with possible blistering, cracking, oozing, or bleeding. This chronic condition, most often seen in infants and children, appears to be the result of a malfunction of the body's immune system.
Exfoliative dermatitis (ecks-FOH-lee-ay-tiv der-mah-TYE-tis) is a condition in which there is widespread scaling of the skin. It is often accompanied by pruritus, erythroderma (redness), and hair loss. It may occur in severe cases of many common skin conditions, including eczema, psoriasis, and allergic reactions.
Sleep hyperhidrosis, commonly known as night sweats, is the occurrence of hyperhidrosis during sleep. There are many potential causes of this condition, including menopause, certain medications, and some infectious diseases.
Folliculitis (foh-lick-you-LYE-tis) is an inflammation of the hair follicles ( follicul means the hair follicle, and -itis means inflammation). This condition is especially common on arms, legs, and in the beard area of men. One of the causes of folliculitis is a bacterium found in poorly chlorinated hot tubs or whirlpools. This leads to a condition called hot tub folliculitis.
Cellulitis (sell-you-LYE-tis) is an acute, rapidly spreading bacterial infection within the connective tissues that is characterized by malaise, swelling, warmth, and red streaks. Note: Do not confuse cellulitis with cellulite, which is discussed earlier in this chapter.
Furuncles (FYOU-rung-kulz), also known as boils, are large, tender, swollen areas caused by a staphylococcal infection around hair follicles or sebaceous glands.
Granulation tissue is the tissue that normally forms during the healing of a wound. This tissue eventually forms the scar.
Granuloma (gran-you-LOH-mah) is a general term used to describe a small, knot-like swelling of granulation tissue in the epidermis ( granul meaning granular, and -oma means tumor). Granulomas can result from inflammation, injury, or infection.
Hair fibers are rod-like structures composed of tightly fused, dead protein cells filled with hard keratin. The darkness and color of the hair is determined by the amount and type of melanin produced by the melanocytes that surround the core of the hair shaft.
Hair follicles (FOL-lick-kulz) are the sacs that hold the root of the hair fibers. The shape of the follicle determines whether the hair is straight or curly.
Mast cells, which are found in the connective tissue of the dermis, respond to injury, infection, or allergy by producing and releasing substances, including heparin and histamine.
Heparin (HEP-ah-rin), which is released in response to an injury, is an anticoagulant. An anticoagulant prevents blood clotting.
Trichomycosis axillaris (try-koh-my-KOH-sis ak-sih-LAR-is) is a superficial bacterial infection of the hair shafts in areas with extensive sweat glands, such as the armpits ( trich/o means hair, myc means fungus, and -osis means abnormal condition). Axillaris is Latin for axillary ( axill means armpit, and -ary means pertaining to).
Hirsutism (HER-soot-izm) is the presence of excessive body and facial hair in women, usually occurring in a male pattern ( hirsut means hairy, and -ism means condition). This condition can be hereditary or caused by a hormonal imbalance.
Heat rash, also known as prickly heat, is an intensely itchy rash caused by blockage of the sweat glands by bacteria and dead cells.
Hyperhidrosis (high-per-high-DROH-sis) is a condition of excessive sweating in one area or over the whole body ( hyper- means excessive, hidr means sweat, and -osis means abnormal condition).
Gangrene (GANG-green), which is death of tissue, is most commonly caused by a loss of circulation to the affected tissues. The tissue death is followed by bacterial invasion that causes putrefaction, and if this infection enters the bloodstream, it can be fatal. Putrefaction is decay that produces foul-smelling odors.
Impetigo (im-peh-TYE-goh) is a highly contagious bacterial skin infection that commonly occurs in children. This condition is characterized by isolated pustules that become crusted and rupture.
The basal layer (BAY-suhl) is the lowest layer of the epidermis. It is here that new cells are produced and then pushed upward. When these cells reach the surface, they die and become filled with keratin.
Keratin (KER-ah-tin) is a fibrous, water-repellent protein. Soft keratin is a primary component of the epidermis. Hard keratin is found in the hair and nails.
Clubbing is the abnormal curving of the nails that is often accompanied by enlargement of the fingertips. This condition can be hereditary but is usually caused by changes associated with oxygen deficiencies related to coronary or pulmonary diseases such as lung cancer.
Koilonychia (koy-loh-NICK-ee-ah), also known as spoon nail, is a malformation of the nails in which the outer surface is concave or scooped out like the bowl of a spoon ( koil means hollow or concave, onych means fingernail or toenail, and -ia means condition). This condition is often an indication of iron-deficiency anemia (see Chapter 5).
Electrolysis (ee-leck-TROL-ih-sis) is the use of electric current to destroy hair follicles in order to produce the relatively permanent removal of undesired hair ( electr/o means electric, and -lysis means destruction).
Lipectomy (lih-PECK-toh-mee) is the surgical removal of fat from beneath the skin to improve physical appearance ( lip means fat, and -ectomy means surgical removal).
Ichthyosis (ick-thee-OH-sis) is a group of hereditary disorders characterized by dry, thickened, and scaly skin ( ichthy means dry or scaly, and -osis means abnormal condition). These conditions are caused either by the slowing of the skin's natural shedding process or by a rapid increase in the production of the skin's cells.
Lipedema (lip-eh-DEE-mah), also known as painful fat syndrome, is a chronic abnormal condition that is characterized by the accumulation of fat and fluid in the tissues just under the skin of the hips and legs ( lip means fat, and -edema means swelling). This condition usually affects women and even with weight loss this localized excess fat does not go away. Note: Don't confuse this condition with lymphedema, discussed in Chapter 6.
Topical steroids such as hydrocortisone and other more potent variations are used in the treatment of various skin disorders and diseases. These drugs, which are derivatives of the natural corticosteroid hormones produced by the adrenal glands, must be used cautiously to avoid potential side effects, which can include irreversible thinning of the skin.
Many over-the-counter face washes recommended for treating acne contain salicylic acid or benzoyl peroxide. These are considered noncomedogenic, meaning that they do not clog pores.
Melanocytes (meh-LA-noh-sites) are special cells that are also found in the basal cell layer. These cells produce and contain a dark brown to black pigment known as melanin.
Melanin (MEL-ah-nin) is the pigment that determines the color of the skin, which depends upon the type and amount of this pigment that is present (Figure 12.2). Melanin also produces spots of color such as freckles and age spots, which are discussed in later sections.
A lipoma (lih-POH-mah) is a benign, slow-growing fatty tumor located between the skin and the muscle layer ( lip means fatty, and -oma means tumor). This fatty tumor is usually harmless, and treatment is rarely necessary unless the tumor is in a bothersome location, is painful, or is growing rapidly.
Nevus (NEE-vus), also known as a mole, is a small, dark skin growth that develops from melanocytes in the skin (plural, nevi). Normally, these growths are benign.
Onychia (oh-NICK-ee-ah), also known as onychitis, is an inflammation of the bed of the nail that often results in the loss of the nail ( onych means fingernail or toenail, and -ia means condition).
Onychocryptosis (on-ih-koh-krip-TOH-sis) is commonly known as an ingrown toenail ( onych/o means fingernail or toenail, crypt means hidden, and -osis means abnormal condition). The edges of a toenail, usually on the big toe, curve inward and cut into the skin. The affected area is prone to inflammation or infection.
Onychomycosis (on-ih-koh-my-KOH-sis) is a fungal infection of the nail ( onych/o means fingernail or toenail, myc means fungus, and -osis means abnormal condition). Depending on the type of fungus involved, this condition can cause the nails to turn white, yellow, green, or black and to become thick or brittle.
Paronychia (par-oh-NICK-ee-ah) is an acute or chronic infection of the skin fold around a nail ( par- means near, onych means fingernail or toenail, and -ia means condition).
An infestation is the dwelling of microscopic parasites on external surface tissue. Some parasites live temporarily on the skin. Others lay eggs and reproduce there.
Pediculosis (pee-dick-you-LOH-sis) is an infestation with lice ( pedicul means lice, and -osis means abnormal condition). In order to get rid of the infestation, the lice eggs, which are known as nits, must be destroyed. There are three types of lice, each attracted to a specific part of the body:
Sweat glands, also known as sudoriferous glands, are tiny, coiled glands found on almost all body surfaces. There are two types, apocrine glands, which are found at hair follicles, and eccrine glands which open onto the skin and are most numerous in the palms of the hands, the soles of the feet, and forehead.
Pores are the openings on the surface of the skin that act as the ducts of the sweat glands.
Systemic lupus erythematosus (sis-TEH-mik LOO-pus er-ih-thee-mah-TOH-sus) (SLE), also known as lupus, is an autoimmune disorder characterized by a red, scaly rash on the face and upper trunk. In addition to the skin, this condition also attacks the connective tissue in other body systems, especially in the joints.
Psoriasis (soh-RYE-uh-sis) is a common skin disorder characterized by flare-ups in which red papules covered with silvery scales occur on the elbows, knees, scalp, back, or buttocks (Figure 12.11).
An ecchymosis (eck-ih-MOH-sis), commonly known as a bruise, is a large, irregular area of purplish discoloration due to bleeding under the skin ( ecchym means pouring out of juice, and -osis means abnormal condition) (Figure 12.5). The plural form is ecchymoses.
Purpura (PUR-pew-rah) is the appearance of multiple purple discolorations on the skin caused by bleeding underneath the skin ( purpur means purple, and -a is a noun ending). These areas of discoloration are smaller than an ecchymosis and larger than petechiae.
An abscess (AB-sess) is a closed pocket containing pus that is caused by a bacterial infection. An abscess can appear on the skin or within other structures of the body.
Purulent (PYOU-roo-lent) means producing or containing pus.
Necrotizing fasciitis (NECK-roh-tiz-ing fas-ee-EYE-tis) is a severe infection caused by group A strep bacteria, which are also known as flesh-eating bacteria. Necrotizing means causing tissue death, and fasciitis is inflammation of fascia. These bacteria normally live harmlessly on the skin; however, if they enter the body through a skin wound, this serious infection can result. If untreated, the infected body tissue is destroyed, and the illness can be fatal.
Pyoderma (pye-oh-DER-mah) is any acute, inflammatory, pus-forming bacterial skin infection such as impetigo ( py/o means pus, and -derma means skin).
Rosacea (roh-ZAY-shee-ah), also known as adult acne, is characterized by tiny red pimples and broken blood vessels. This chronic condition of unknown cause usually develops in individuals with fair skin between 30 and 60 years of age.
Rhinophyma (rye-noh-FIGH-muh), also known as bulbous nose, usually occurs in older men ( rhin/o means nose, and -phyma means growth). This condition is characterized by hyperplasia (overgrowth) of the tissues of the nose and is associated with advanced rosacea.
Liposuction (LIP-oh-suck-shun), also known as suction-assisted lipectomy, is the surgical removal of fat beneath the skin with the aid of suction.
Rhytidectomy (rit-ih-DECK-toh-mee), also known as a facelift, is the surgical removal of excess skin and fat from the face to eliminate wrinkles ( rhytid means wrinkle, and -ectomy means surgical removal).
-Pediculosis capitis is an infestation with head lice. -Pediculosis corporis is an infestation with body lice. -Pediculosis pubis is an infestation with lice in the pubic hair and pubic region.
Scabies (SKAY-beez) is a skin infection caused by an infestation of itch mites. These tiny mites cause small, itchy bumps and blisters by burrowing into the top layer of human skin to lay their eggs. Medications applied to the skin kill the mites; however, itching may persist for several weeks.
A plaque (PLACK) is a scaly, solid raised area of closely spaced papules. For example, the lesions of psoriasis are plaques (Figure 12.11). Note: The term plaque also means a fatty buildup in the arteries (see Chapter 5) and a soft substance that forms on the teeth (see Chapter 8).
Scales are flakes or dry patches made up of excess dead epidermal cells. Some shedding of these scales is normal; however, excessive shedding is associated with skin disorders such as psoriasis.
An epidermoid cyst (ep-ih-DER-moyd SIST), often referred to as a sebaceous cyst is a closed sac that is found just under the skin. These cysts contain yellow, fatty material and are usually found on the face, neck, or trunk.
Seborrhea (seb-oh-REE-ah) is overactivity of the sebaceous glands that results in the production of an excessive amount of sebum ( seb/o means sebum, and -rrhea means flow or discharge).
Polyp (POL-up) is a general term used most commonly to describe a mushroom-like growth from the surface of a mucous membrane, such as a polyp in the nose. These growths have many causes and are not necessarily malignant.
Skin tags are small, flesh-colored or light-brown polyps that hang from the body by fine stalks. Skin tags are benign and tend to enlarge with age.
A basal cell carcinoma (BAYS-al) is a malignant tumor of the basal cell layer of the epidermis. This is the most common and least harmful type of skin cancer because it is slow growing and rarely spreads to other parts of the body. The lesions, which occur mainly on the face or neck and tend to bleed easily, are usually pink and smooth and are raised with a depression in the center (see carcinoma of the lip in Chapter 6, Figure 6.12).
Squamous cell carcinoma (SKWAY-mus) originates as a malignant tumor of the scaly squamous cells of the epithelium; however, it can quickly spread to other body systems. These cancers begin as skin lesions that appear to be sores that will not heal or that have a crusted look (Figure 12.13).
Epithelial tissues (ep-ih-THEE-lee-al) form a protective covering for all of the internal and external surfaces of the body.
Squamous epithelial tissue (SKWAY-mus) forms the upper layer of the epidermis. Squamous means scale-like. This layer consists of flat, scaly cells that are continuously shed.
Erythema pernio, also known as chilblains, is a purple-red inflammation that occurs when the small blood vessels below the skin are damaged, usually due to exposure to cold and damp weather. When warmth restores full circulation, the affected areas begin to itch; however, they usually heal without treatment.
Sunburn is a form of erythema in which skin cells are damaged by exposure to the ultraviolet rays in sunlight. This damage increases the chances of later developing skin cancer.
Exfoliative cytology (ecks-FOH-lee-ay-tiv sigh-TOL-oh-jee) also referred to as skin scraping, is a technique in which cells are scraped from the tissue and examined under a microscope. Exfoliation is the removal of dead epidermal cells, often through sanding or chemabrasion (which is discussed in the next section), and is sometimes done for cosmetic purposes.
Sunscreen that blocks out the harmful ultraviolet B (UVB) rays is sometimes measured in terms of the strength of the sun protection factor (SPF). Some sunscreens also give protection against ultraviolet A (UVA) rays.
Although hair is dead tissue, it appears to grow because the cells at the base of the follicle divide rapidly and push the old cells upward. As these cells are pushed upward, they harden and undergo pigmentation.
The arrector pili (ah-RECK-tor PYE-lye) are tiny muscle fibers attached to the hair follicles that cause the hair to stand erect. In response to cold or fright, these muscles contract, causing raised areas of skin known as goose bumps. This action reduces heat loss through the skin.
Melanin has the important function of protecting the skin against some of the harmful ultraviolet rays of the sun. Ultraviolet (UV) refers to light that is beyond the visible spectrum at the violet end. Some UV rays help the skin produce vitamin D; however, other rays damage the skin.
The dermis (DER-mis), also known as the corium, is the thick layer of living tissue directly below the epidermis. It contains connective tissue, blood and lymph vessels, and nerve fibers. Also found in the dermis are the hair follicles, sebaceous glands, and sweat glands, which are the related structures of the integumentary system (as well as the nails).
The skin is a complex system of specialized tissues made up of three basic layers: the epidermis, dermis, and subcutaneous layers (Figure 12.1). The term cutaneous (kyou-TAY-nee-us) means pertaining to the skin ( cutane means skin, and -ous means pertaining to).
The epidermis (ep-ih-DER-mis), which is the outermost layer of the skin, is made up of several specialized epithelial tissues ( epi- means above or upon, derm means skin, and -is is a noun ending). The epidermis does not contain any blood vessels or connective tissue. It is therefore dependent on lower layers for nourishment.
The nail bed, which joins the nail body to the underlying connective tissue, nourishes the nail. The blood vessels here give the nail its characteristic pink color.
The free edge, which is the portion of the nail not attached to the nail bed, extends beyond the tip of the finger or toe.
Functions of the Integumentary System
The integumentary system (in-teg-you-MEN-tah-ree), which is made up of the skin and its related structures, performs important functions in maintaining the health of the body. The term integument comes from the Latin word meaning to cover or enclose.
Hidrosis (high-DROH-sis) is the production and excretion of perspiration.
The milk-producing mammary glands, which are modified sweat glands, are sometimes classified with the integumentary system. However, they also are part of the reproductive system and are discussed in Chapter 14.
Functions of Related Structures: The related structures of the integumentary system are the sebaceous glands, sweat glands, hair, and nails (Figure 12.1).
The sebaceous glands (seh-BAY-shus) secrete sebum (oil) that lubricates the skin and discourages the growth of bacteria on the skin. The sweat glands help regulate body temperature and water content by secreting sweat. A small amount of metabolic waste is also excreted through the sweat glands. Hair helps control the loss of body heat. Nails protect the dorsal surface of the last bone of each toe and finger.
Functions of the Skin
The skin forms the protective outer layer covering the external surfaces of the entire body. The skin waterproofs the body and prevents fluid loss. Intact (unbroken) skin plays an important role in the immune system by blocking the entrance of pathogens into the body (see Chapter 6). Skin is the major receptor for the sense of touch. Skin helps the body synthesize vitamin D, an essential nutrient, from the sun's ultraviolet light, while screening out some harmful ultraviolet radiation. The average adult has 2 square yards of skin, making it the largest bodily organ.
Mohs surgery is a technique used to treat various types of skin cancer. Individual layers of cancerous tissue are removed and examined under a microscope one at a time until a margin that is clear of all cancerous tissue has been achieved.
The term laser is an acronym in which the letters stand for light amplification by stimulated emission of radiation. Lasers are used to treat skin conditions and other disorders of the body.
Sebaceous glands (seh-BAY-shus) are located in the dermis layer of the skin and are closely associated with hair follicles (Figure 12.1).
These glands secrete sebum (SEE-bum), which is an oily substance that is released through ducts opening into the hair follicles. From here, the sebum moves onto the surface and lubricates the skin. Because sebum is slightly acidic, it discourages the growth of bacteria on the skin.
The subcutaneous layer (sub-kyou-TAY-nee-us) is located just below the layers of the skin and connects the skin to the surface muscles.
This layer is made up of loose connective tissue and adipose tissue (AD-ih-pohs). Adipose means fat. Cellulite is a term used to describe deposits of dimpled fat around the buttocks and thighs. This is not a scientific term, and medical authorities agree that cellulite is simply ordinary fatty tissue. Note: Do not confuse cellulite with cellulitis, which is discussed later in this chapter. Lipocytes (LIP-oh-sights), also known as fat cells, are predominant in the subcutaneous layer where they manufacture and store large quantities of fat ( lip/o means fat, and -cytes means cells).
Mycosis (my-KOH-sis) describes any abnormal condition or disease caused by a fungus ( myc means fungus, and -osis means abnormal condition or disease).
Tinea (TIN-ee-ah) is a fungal infection that can grow on the skin, hair, or nails. This condition is also known as ringworm, not because a worm is involved, but because as the fungus grows on the skin, it spreads out in a worm-like circle, (Figure 12.12). Tinea does not create this pattern when it grows on the nails.
Sensory nerve endings in the dermis are the sensory receptors for stimuli such as touch, temperature, pain, and pressure.
Tissues Within the Dermis: Collagen (KOL-ah-jen), which means glue, is a tough yet flexible fibrous protein material found in the skin and also in the bones, cartilage, tendons, and ligaments... - Histamine (HISS-tah-meen), which is released in response to allergens, causes the signs of an allergic response, including itching and increased mucus secretion.
Scleroderma (sklehr-oh-DER-mah) is an autoimmune disorder in which the connective tissues become thickened and hardened, causing the skin to become hard and swollen ( scler/o means hard, and -derma means skin). This condition can also affect the joints and internal organs.
Urticaria (ur-tih-KARE-ee-ah), also known as hives, are itchy wheals caused by an allergic reaction ( urtic means rash, and -aria means connected with).
Pigmented birthmarks include nevi, also known as moles, as well as café-au-lait spots and other irregularities in skin color.
Vascular birthmarks are caused by blood vessels close to the skin's surface. These are the most common type of birthmark and are sometimes called salmon patches or red birthmarks.
