Chapter 4The Integumentary system

It is composed of the skin, accessory structures and subcutaneous tissue. A-The skin is composed of two layers:

1-Epidermis - The outermost layer. Its cells continually undergo

mitosis and are replaced approximately every 30 days. - The epidermis contains sensory receptors for touch, pressure, temperature, vibration, and pain.

- The main component of the epidermis and of the skin appendages( the nails and the hair) is the protein keratin, produced by cells called keratinocytes. Melanocytes synthesize and secrete melanin which protect cells from ultraviolet radiation.

- Langerhans' cells are macrophages that recognize foreign particles or microorganisms and present them to T lymphocytes . Ultraviolet radiation reduces their ability to prevent cancer.

2-DermisBlood vessels in the dermis supply the dermis and epidermis .With a decrease in body temperature, sympathetic nerves to the blood vessels are activated and increase the release of norepinephrine, causing constriction of the vessels and a conservation of body heat. If body temperature is too high, sympathetic stimulation of the dermal blood vessels is reduced, dilating the vessels and allowing for the transfer of body heat to the environment.

 B-Subcutaneous LayerLying beneath the dermis, composed of fat and connective tissue and acts as both a shock absorber , a heat insulator and a calorie reserve

station. C-Accessory structures

1-Hair and Nails-The nails are keratinized plates that extend from

the fingers and the toes. The nails protect the fingertips.

-The hair is hardened keratin that grows at variable rates on different parts of the body .

2-Sebaceous GlandsThe sebaceous glands accompany the hair follicles. They secrete an oily substance called sebum into the surrounding canal. Sebaceous glands are present all over the body, especially on the face, chest, and back. Testosterone increases the size of the sebaceous glands and the production of sebum. Testosterone levels increase in males and females during puberty.

 3-Sweat Glands:There are two types of sweat

glands.a- Eccrine sweat glands are distributed over the entire body and function mainly in cooling the body by means of evaporative heat loss. They are especially concentrated on the hands, feet, and forehead.

b- Apocrine glands are mainly located in the axillae (armpits) and in the pubic and anal areas. When acted upon by surface bacteria, the secretions of the apocrine glands cause the characteristic odor of perspiration.

Vitamin DThe skin plays a vital role in the body's use of

vitamin D .

Vitamin D is a hormone obtained in the diet in an inactive form. It is required both for the absorption of calcium from the gut and to

reduce the renal excretion of calcium .

-It first must be activated in the skin as a result of ultraviolet (UV) radiation, after which it is further acted upon by the kidney and the liver.

-Vitamin D activation is increased in response to a decrease in serum calcium.

 Pathophysiologic ConceptsMany different lesions occur on the skin. They are described on the basis of size, depth, color, and consistency.

BullaA bulla is a large, raised area on the skin measuring more than 1.0cm and filled with watery fluid,. Bullae are large blisters that can occur after a burn.

CrustA crust is the accumulation of dried serous (serum-like) or seropurulent (pus) exudate on the skin (e.g., the crust seen on an impetigo or herpes lesion). It is usually golden in color.

 ErosionAn erosion is loss of superficial epidermis. Typically the area is moist, but it does not bleed (e.g., the skin after bursting of a blister or vesicle).

FissureA fissure is a linear crack in the skin, for example, as seen with athlete's foot. The fissure may be pink or red, but there is usually no bleeding.

KeloidA keloid is a scar formation on the skin, occurring after a

trauma. Keloids appear raised, red, and firm..MaculeA macule is a flattened area of the skin, smaller than 1.0

cm in diameter characterized by a change in color .

 PapuleA papule is a solid, elevated mass, smaller than 1.0 cm in diameter. Examples of papules include elevated moles and warts.

NoduleA nodule is a solid, elevated mass with a measurement between 1.0 cm and 2.0 cm in diameter. It is firmer in consistency than a papule.

Petechia A deep red spot of pinpoint hemorrhage under the skin. Petechiae may signify a bleeding disorder or fragility of the capillaries and may accompany a serious infection.

PruritusIt refers to itching of the skin. Pruritus may occur as a primary response to a surface irritant or inflammation, for example, after a mosquito bite. Pruritus may occur secondarily to a systemic disease, such as liver or kidney failure.

PurpuraA purpuric lesion is a large patch of purple discoloration under the skin associated with hemorrhage. It may result from thrombocytopenia (decreased platelets), trauma or an allergic response.

PustuleA pustule is an elevated vesicle filled with pus. Examples of pustules are the lesions of impetigo or acne.

ScaleA scale is a flake of epidermis. Examples of scaling are seen in dandruff or dried skin.

ScarA scar is an area of the body where the skin has been replaced by fibrous tissue (e.g., a burn scar).

UlcerAn ulcer is an area with loss of epidermal and deeper layers of the skin that may bleed and scar. An example of an ulcer is a decubitus ulcer (pressure sore).

UrticariaUrticaria, consists of raised edematous plaques (wheals) associated with intense itching (pruritus). Urticaria results from the release of histamine during an inflammatory response to

an allergen..VesicleA vesicle is a small, raised area on the skin with a measurement of less than 1.0 cm. It is formed by the presence of serous fluid within the skin layers (e.g., a chickenpox blister)

Conditions of Disease or Injury1-Contact Dermatitis

Is an acute or chronic inflammation of the skin caused by exposure to an irritant (irritant dermatitis) or allergen (allergic dermatitis). Common causes of irritant dermatitis include: soaps, detergents and household cleaners.

Clinical ManifestationsLocalized redness and oozing vesicles in the area of contact. The vesicles burst and crust. Pruritus may be intense.

Allergic dermatitis typically presents 1 to 2 days after exposure.

 Diagnosis

-A good history is the key to diagnosis.- A circle of lesions around the wrist may indicate an allergy

to a bracelet or watch. -Lesions below the umbilicus may indicate an allergy to

the metal of a zipper. -Reddened, irritated hands may indicate a response to

dishwashing.Treatment

-Avoiding exposure prevents recurrence. -Cool compresses reduce inflammation.

-Antihistamines may be used to reduce itching. -Short-term, topical steroidal therapy.

-For severe attacks involving the eyes and face, systemic corticosteroids is used.

2-AcneAcne is an active infection of sebaceous glands and is commonly seen at puberty and common in boys.

Causes of Acne -The sharp increase in androgens .

-Estrogen opposes the action of androgen on the sebaceous glands.

Clinical Manifestations Acne may present with a variety of lesions as

blackheads, whiteheads, nodules, pustules, cysts, and scars. Lesions are commonly over the face, back, and shoulders.

In women, acne may increase before or during the menstrual period when estrogen levels are lowest.

Treatment- Antibacterial soap may reduce bacterial contamination .- Topically applied antibiotics(tetracycline, erythromycin, or

clindamycin )often in combination with benzoyl peroxide, may be prescribed for use once or twice a day.

- Oral low-dose antibiotic therapy (e.g., tetracycline, doxycycline) reduce bacterial growth.

It requires several weeks to be effective.* Oral tetracycline damages developing teeth; therefore, it

is contraindicated in pregnant women or women planning to get pregnant.

- Birth-control pills containing estrogen can reduce sebum production. They may be used to treat acne in girls and women.

3- Psoriasis Red, raised scaly plaques that can cover any body surface. Causes of Psoriasis It is an autoimmune disorder leading to abnormal

cellular proliferation and turnover. Normal epidermal cell turnover is approximately 28 to 30 days; with psoriasis, the epidermis in affected areas may shed every 3 to 4 days.

Clinical Manifestations - Well-demarcated (clearly bordered) erythematous area

covered with silvery white scales develop especially over knees, elbows, scalp, and in skin folds.

- Lesions typically develop insidiously, with just one or two lesions later coalescing into many.

- Separation of the nail is common. - Symptoms typically improve in summer and worsen in

winter.

4- Rubeola Also called 10-day measles or red measles, is an

upper respiratory tract infection caused by the paramyxovirus.

Rubeola is usually seen in children and is transmitted by way of inspired droplets. It has a 7- to 12-day incubation period and is highly contagious.

Clinical Manifestation -Prodromal symptoms include high fever, cough,

runny nose, and enlargement of lymph nodes. -Active infection is characterized by Koplik's spots

over the buccal (cheek) mucosa. A Koplik's spot is a pinpoint white spot surrounded by a red ring.

-A maculopapular rash with erythema, beginning on approximately day 3 or 4, starts on the face, spreads to the trunk, and finally the extremities. The rash lasts approximately 4 days.

Complications- Measles encephalitis.- Pneumonia.Treatment-Primary treatment is prevention by vaccination

with a live attenuated virus at 15 months after birth. A booster is usually administered at 4 to 5 years, and sometimes in the teen years.

-Treatment of measles infection is supportive and may involve antibiotics if a secondary bacterial infection develops.

 5-Rubella

Also called German measles, is a viral infection of the respiratory tract caused by the rubella virus. There is a 14- to 21-day incubation period, followed by prodromal symptoms lasting 1 to 4 days. A rash then develops. Rubella is very contagious during the prodromal stage.

Clinical Manifestations-Prodromal stage is characterized by low-grade

fever, malaise, lymph node enlargement (especially post-auricular), sore throat, and headache.

-Active infection is characterized by a diffuse maculopapular rash, which begins on the trunk and spreads to the extremities. The rash lasts for approximately 2 to 3 days.

Complications -Infection in a pregnant woman, especially during the first

trimester, may cause severe birth defects in her infant. Treatment -Vaccination with a live, attenuated virus at 15 months, at

4 to 5 years, and in the teen years. The vaccine, called an MMR vaccine, for measles (rubeola), mumps, and rubella.

- All women of childbearing age should be tested for the presence of antibodies against rubella (a rubella titer test). A woman who is antibody negative should be immunized against the virus.

• Treatment of rubella infection is supportive, and is focused on keeping the individual well-hydrated and rested.

6-Chickenpox and Shingles Chickenpox (varicella) and shingles (zoster) are

infections caused by the varicella-zoster virus. Infection by the varicella-zoster virus causes pruritic, fluid-filled vesicles on the skin.

Chickenpox is the primary infection by the virus and is usually an illness of childhood, and is highly contagious by way of respiratory droplets. It has an incubation period of 7 to 21 days and is contagious during 24 hours before lesions appear and until all lesions are crusted over. The disease is usually self-limiting and resolves within 7 to 14 days.

Shingles (Zoster)is caused by the virus that has remained latent in a sensory nerve tract after recovery from chickenpox. It typically occurs along the dermatome

(skin region) innervated by the infected nerve .Zoster often is seen in the elderly or in individuals who have a reduced immune system caused by illness or stress.

Clinical Manifestations of chicken pox-Low-grade fever and malaise before vesicles appear.

-The rash begins as red macules, usually first appearing on the trunk and spreading to the face and extremities. Within a few hours, the macules become fluid-filled vesicles. The vesicles burst after a few days and crust over.

- Clinical manifestations of Shingles The vesicles of shingles appear unilaterally along the infected

dermatome specially on the face, neck, and thoracic areas. The lesions may be small or large and few or many in number.

Shingles may be very painful. Diagnosis - history and physical examination. - vesicles are unilateral and painful. Treatment -Prevention with the varicella vaccine. -Treatment is mainly supportive to prevent skin infections. - Calamine lotion, and antihistamines may be used to reduce

itching. - In children, the nails may be cut to reduce scratching. -Treatment of shingles includes analgesics for pain and

antiviral drugs to limit viral replication.

7-Warts Warts(verrucae) are caused by infection with the

human papillomavirus (HPV). There are many different strains of HPV. Some strains preferentially infect the genital or anal region, causing genital warts, whereas others colonize the fingers and hands, causing simple warts. Warts are passed by skin-to-skin contact. Genital warts are considered a sexually transmitted disease.

Clinical Manifestations -Skin warts may be flat or round, large or small

papules. -Genital warts have a cauliflower-type appearance.

They may be seen on the head or shaft of the penis, on the labia, in the vagina, or surrounding the anus.

Diagnosis -Diagnosis is made by history and physical

examination. -Occasionally, a biopsy of the lesion may be taken for

histologic confirmation of HPV.Complications - Cervical cancer in women.Treatment -Warts go away on their own when the immune system

is stimulated with bleeding of the wart. -Irritation of a skin or plantar wart by the application of

salicylic acid, formaldehyde, or other skin irritants may stimulate an immune reaction against the wart.

All types of warts frequently reappear after treatment. -Liquid nitrogen, cryosurgery, or laser may be used to

remove warts on the genital or esophageal regions.

8-Bacterial Infections of the Skin a-Impetigo A superficial skin infection, usually caused by

Staphylococcus or group A streptococcal infection. Most commonly occurs in children, presenting as

pustules on the skin filled with a honey-colored fluid. The pustules burst and crust over.

It is highly contagious, and easily passes from one area of the body to another and from person to person .

Neonates may develop bullous impetigo from cross-contamination in the nursery. This type of impetigo is caused by Staphylococcus aureus and is highly contagious.

Clinical Manifestations• Localized pustules, filled with a honey-colored fluid which

burst and crust, anywhere on the body. Diagnosis -Diagnosis is made by history and physical examination. -Bacterial culture and drug sensitivity testing .Complications -Acute post-streptococcal glomerulonephritis -Widespread infection in an infant is possible.Treatment -Systemic antibiotics may be administered after culture. - Topical antibiotics may be adequate if the lesion is small. -Sterilization of towels and frequent hand washing .

b-Cellulitis Is a bacterial infection of the dermis or subcutaneous

layer of the skin. Cellulitis typically occurs after a surface wound or bite. Clinical Manifestations -The skin appears swollen and red and is tender and warm

to the touch. An exudate of serous or purulent fluid may be present.

-Fever may be present. Diagnosis Diagnosis is made by history and physical examination. Treatment -Warm soaks . -Systemic antibiotics are necessary.

c-Scarlet Fever Is a skin rash caused by toxins released during infection with group

A beta-hemolytic streptococci. It is usually associated with a pharyngeal streptococcal infection. Clinical Manifestations -The rash is usually pink, mainly over the neck, trunk, and groin,

with a feeling similar to fine sandpaper. -The rash is typically accompanied by sore throat, fever, headache,

and nausea. Diagnostic Tools -History and physical examination -A throat culture is usually positive for group A beta-hemolytic

streptococci. Complications Post-streptococcal glomerulonephritis, rheumatic fever, and

peritonsillar abscess . Treatment Treatment is with penicillin or, if the individual is allergic to

penicillin, erythromycin .

9- Fungal Infections of the Skin Is considered superficial infections and are typically

described based on the site of infection. - Tinea is fungal infections of the skin : ..Tinea pedis is an infection of the foot (e.g., athlete's

foot) .. tinea capitis, an infection of the scalp. ..Tinea versicolor is a fungal infection of the body that

may result in patches of discoloration that are worsened by exposure to sunlight.

- Candidiasis is fungal infections of the mouth (thrush), gastrointestinal (GI) tract, and vagina usually are a result of the yeastlike fungus Candida albicans . C. albicans is part of the normal human flora that, under some conditions, may multiply excessively and cause symptoms.

Clinical Manifestations -Skin infections cause inflammation with erythema

and itching. -Ringworm may present as a ring of erythema with a

pale interior. Scaling of the edges may be present. - Vaginal infections are associated with a cheese-like

white discharge. - Oral infections present with multiple white

ulcerations surrounded by erythema, which may be extremely painful.

Diagnosis - Fungal infections may be diagnosed by history and

physical examination. - Microscopic examination of skin .

Complications -Surface infections may become secondarily infected by

bacteria. -Deep fungal infections (internal) may cause significant

morbidity and mortality. -with tinea capitis, alopecia (hair loss) may occur. -Painful oral lesions that interfere with eating may

contribute to the wasting seen in individuals suffering from AIDS.

Treatment - Skin infections are treated with type-specific antifungal

medications applied topically or occasionally given systemically.

-Candidiasis is treated with antifungal cream or suppositories.-Deep fungal infections may require extensive, specific antifungal therapy and hospitalization.

10- Burns Burns may result from exposure of the skin to high

temperature, electrical shock, or chemicals. Burns are classified according to tissue depth of the burn and the extent of the body surface area that has been burned.

Depth of a Burn• A first-degree burns are limited to the epidermis. There is

erythema and pain but no immediate blistering. Healing is spontaneous and occurs within 3 to 4 days. The burn does not scar. There are usually no complications. Sunburn is an example of a first degree burn.

• A second-degree burns extend through the epidermis and into the dermal layer. The burn is extremely painful and blisters within minutes. The burn usually heals without scarring. Complications are uncommon, although secondary infection of the wound may occur.

• A third-degree burns extend through the epidermis and the dermis and into the subcutaneous tissue layer. Capillaries and veins may be destroyed, and blood flow to the area may be reduced. Nerves are destroyed, so the burn itself is not painful, although surrounding areas typically show extremely painful second-degree burns. A third-degree burn may require months to heal, and surgical debridement and grafting are necessary.

• Fourth-degree burns extend through muscle, bone, and internal tissues.

Extent of a Burn• The rule of nines. With this method, each arm is

considered 9% of the body surface area, each leg 18%,the front and back torso each 18%, the head 9%, and the genital area 1%. Based on TBSA burned, major burns are defined as those involving between 25% and 40% of the body surface area of an adult and between 15% and 25% of the surface area of a child. Burns of greater than 40% in adults or 25% in children are associated with significant mortality.

• Besides considering TBSA burned and depth of burns, the overall health and age must be taken into consideration. Children and the elderly have increased mortality.

• An individual suffering from a severe burn should be transferred to a burn care facility as soon as possible.

Traetment - The burned area should be immediately immersed under cool

water(not ice). - Clothes should not be removed from a serious burn, because

removing clothes may also remove skin. - Burns to the hands, face, and genitals should be evaluated by

medical personnel. - First-degree burns usually require only prolonged exposure to

large amounts of cool water or the application of cool compresses and anti-inflammatory medication.

- First-degree chemical burns should be flushed with cool water for several minutes.

- Burns deeper than first-degree require antimicrobial therapy - Major burns require quick intravenous fluid replacement. To maintain blood pressure and prevent irreversible shock,

infusions in an adult may reach 30L in 24 hours. The high rate of fluid replacement also flushes the kidney and

reduces the risk of renal failure.

 11-Decubitus Ulcer

Also called pressure sores or bed sores, that occur after the breakdown of the epidermis, the dermis, and, occasionally, the subcutaneous tissue and underlying bone.

Usually seen in individuals who are bedridden or have significantly decreased mobility, especially if

are accompanied by poor nutritional status .There are three forces that together produce a decubitu ulcer: pressure, friction, and moisture.

It usually forms on an area of the skin overlying a bony process if the pressure in that area goes unrelieved for a long period, causing collapse of the supplying blood vessels. This collapse leads to tissue hypoxia and cellular death.

Clinical Manifestations - An early sign is redness that does not disappear with fingertip

pressure (non-blanching). - Pain and systemic signs of inflammation, including fever and

increased white blood cell. Diagnosis - Individuals at high risk should be checked frequently for an early

stage of ulcer development. Early stage is suggested by skin that remains blanched with pressure

for more than a brief period. Treatment - Prevention is essential and involves turning bedridden individuals

frequently (at least every 2 hours). - Caloric intake should be kept high to assist in immune function and

to maintain overall general good health. - If a pressure sore does develop, relief of the pressure on the skin

and the placement of a clean, flat, non-bulky dressing are required.