Transcript الشريحة 1

Chapter 4
The 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-Dermis
Blood 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 Layer
Lying 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 Glands
The 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 D
The 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 Concepts
Many different lesions occur on the skin. They are
described on the basis of size, depth, color, and
consistency.
Bulla
A 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.
Crust
A crust is the accumulation of dried serous (serumlike) or seropurulent (pus) exudate on the skin
(e.g., the crust seen on an impetigo or herpes
lesion). It is usually golden in color.
Erosion
An 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).
Fissure
A 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.
Keloid
A keloid is a scar formation on the skin, occurring after a
trauma. Keloids appear raised, red, and firm..
Macule
A macule is a flattened area of the skin, smaller than 1.0
cm in diameter characterized by a change in color.
Papule
A papule is a solid, elevated mass, smaller than 1.0
cm in diameter. Examples of papules include
elevated moles and warts.
Nodule
A 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.
Pruritus
It 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.
Purpura
A 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.
Pustule
A pustule is an elevated vesicle filled with pus. Examples
of pustules are the lesions of impetigo or acne.
Scale
A scale is a flake of epidermis. Examples of scaling are seen in
dandruff or dried skin.
Scar
A scar is an area of the body where the skin has been replaced by
fibrous tissue (e.g., a burn scar).
Ulcer
An 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).
Urticaria
Urticaria, 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..
Vesicle
A 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 Injury
1-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 Manifestations
Localized 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-Acne
Acne 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 7to 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 crosscontamination 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.