Module 8 Flashcards
What is the first line of defence against microbes
skin and mucous membrane
What are major functions of the skin
-Protect against microorganisms
-Protect against UV radiation
-Prevent loss of body fluids
-Protect against mechanical stress
-Regulate body temperature
-Produce vitamin D
-Facilitate sensation
What are the 3 main layers of the skin
- epidermis- consists of epithelial tissue
- dermis- consists of connective tissue, hair follicles, sebaceous glands, eccrine glands
- hypodermis - compromises of connective tissue
What are some accessory structures found in the skin
Hair follicles, sebaceous glands, and two types of sweat glands (eccrine & apocrine)
What are some naturally occurring breaks in the human skin that allow bacteria to enter the body and cause infection?
The hair shaft and the sheathing follicle protrude from the skin, allowing bacteria to travel down the follicle and into the base, in the dermis. The sweat and sebaceous glands also have openings on the surface of the skin through which bacteria may travel down to the dermis and cause infection.
What can be a result of skin lesions
trauma to the skin, inflammation, infections, skin tumours, or can be caused by disorders of other body systems
How are skin lesions classified
Appearance, location, duration of presence, colour, elevation, texture, presence of pain or itching, type of exudate
General treatment for skin lesions
antihistamines or glucocorticoids for pruritus, avoidance of an offending allergen is prescribed to reduce the risk of recurrence, electrodessication or cryosurgery is used for precancerous lesions
Skin lesions are often itchy and uncomfortable. Why is this and how can this manifestation be treated?
Bacterial infections and reactions caused by allergens may spur the release of histamines, which can cause inflammation and pruritus, or itching, by stimulating the many sensory nerve endings in the skin. Antihistamines and glucocorticoids may be prescribed to relieve itching, and further pruritus may be prevented with the use of topical antiallergen creams and ointments.
How is contact dermatitis caused, manifest and treated
-Exposure to an allergen (immune system response), such as metals, cosmetics, soaps, chemicals, or plants (e.g., poison ivy), causes a reaction. The reaction may be immediate or delayed, or it may appear after repeated exposures.
-Direct chemical or mechanical irritation does not involve the immune system; instead, inflammation is the result of direct exposure.
-Manifests as red, edematous skin, often pruritic or painful (as demonstrated in the illustration).
-Treatment involves removal of the irritant and administration of topical glucocorticoids.
Urticaria (Hives) causation, manifestation, treatment
Hives (urticaria) are a manifestation of a type I hypersensitivity reaction, often the result of ingestion of such substances as shellfish, certain fruits, or drugs.
Subsequent release of histamine causes the eruption of hard, erythematous lesions on the skin; these lesions are highly pruritic.
Occasionally hives develop in the pharyngeal mucosa, obstructing the airway and resulting in difficulty breathing.
Other signs and symptoms of a reaction include red, edematous skin that is sometimes pruritic or painful.
Treatment involves administration of antihistamines or, in more serious cases, use of topical or oral glucocorticoids.
Atopic Dermatitis (Eczema) causation, manifestation, treatment
Atopic dermatitis is a common problem in infants but may persist into adulthood.
Atopic means that there is an inherited tendency toward allergic conditions; family history in such cases often includes eczema, allergic rhinitis (also known as hay fever), and asthma.
Chronic inflammation results from responses to allergens; eosinophilia and an increased serum IgE level reflect the allergic basis of this condition.
In adults, the skin appears dry and scaly (lichenification), and pruritus is common.
In infants, lesions are red, moist, covered with crusts, and pruritic.
Complications generally involve infection.
Treatment includes topical glucocorticoids, antihistamines, or both.
Psoriasis causation, treatment, manifestation
chronic inflammatory skin disorder considered to be of genetic origin. Onset usually occurs in the teen years, and the disorder is marked by remissions and exacerbations.
Psoriasis results from abnormal T-cell activation and an increase of cytokines in affected tissues.
Excessive proliferation of keratinocytes occurs. Also, the rate of cellular proliferation is greatly increased leading to thickening of the dermis.
Lesions are found on the face, scalp, elbows, and knees.
Manifestations include an itching or burning sensation, red scaly patches of skin, dry cracked skin that may bleed, and swollen stiff joints.
Treatment involves the use of glucocorticoids, tar preparations, and antimetabolites.
Pemphigus causation, manifestation, treatment
is an autoimmune disorder that comes in several forms: pemphigus vulgaris, pemphigus foliaceus, and pemphigus erythematosus.
Autoantibodies disrupt the cohesion between epidermal cells, resulting in blister formation.
Blisters first form on the oral mucosa or scalp, then spread over the face and trunk. Blisters are painful but not pruritic.
Vesicles enlarge and tend to rupture, leaving large denuded areas of skin covered with crusts.
Treatment of pemphigus generally involves the use of systemic glucocorticoids and immunosuppressants.
Scleroderma causation, manifestation, treatment
occur as a purely integumentary disorder or may be systemic, affecting the viscera.
The primary cause is unknown, but collagen deposition is observed in all cases.
Collagen deposits cause inflammation and fibrosis, which is accompanied by a less functional capillary network.
Hard, shiny, tight, immovable areas of the skin develop. When the face is affected, movement of the mouth and eyes is impaired.
Scleroderma may also affect the microcirculation of various organs, leading to renal failure, intestinal obstruction, or respiratory failure.
Diversity of types of cases means medications vary dramatically based on manifestations. Symptomatic treatment is required, and broad-spectrum immunosuppression drugs and hematopoietic bone marrow or stem cell transplantation may be used.
What is Dupuytren’s Contracture
-a slowly developing hand deformity.
-Exact cause unknown
-Thickening of skin on palm progressing to formation of tissue which contracts and pulls fingers into bent position
Treatments depend on severity and range from stretching to surgery
How can the skin disorder scleroderma also be responsible for renal failure?
Scleroderma involves the deposition of collagen, which causes tissue to be less elastic and more rigid, affecting capillary networks. Collagen deposition in the capillaries serving organs can cause obstructions that result in serious damage to organ tissue.
Bacterial Infections: Cellulitis (Erysipelas) - treatment, manifestation, causation
-an acute infection of the dermis and subcutaneous tissue, generally caused by Staphylococcus aureus, streptococci, or other bacteria.
-Cellulitis is usually the result of an injury, a furuncle (boil), or an ulcer.
The condition is characterized by redness, swelling, warmth, and pain or tenderness.
-Cellulitis, which frequently affects the lower trunk or legs, is sometimes accompanied by the development of red streaks along lymph vessels proximal to the infected area.
-Warm compresses promote drainage of lesions. Systemic antibiotics are used to treat the infection; analgesics are used for pain.
Bacterial Infections: Furuncles (Boils)
-A furuncle is an infection, usually caused by S. aureus, that begins in a hair follicle (folliculitis) and spreads into the surrounding dermis.
-Furuncles occur most commonly on the face, neck, and back.
The lesion—initially a firm, red, painful nodule—develops into a large, painful mass that often drains large amounts of pus.
-Squeezing a boil may spread the infection through autoinoculation.
-A collection of furuncles may fuse to form a carbuncle, a large infected mass, which may drain through several sinuses or develop into an abscess.
Treatment involves moist compresses to drain furuncles or surgical drainage.
Bacterial Infections: Impetigo
a common skin infection in infants and children, limited to the epidermis.
S. aureus may cause this highly contagious infection in neonates; in older children it may also be caused by group A beta-hemolytic Streptococcus.
Lesions, which most commonly occur on the face, begin as small vesicles that rapidly enlarge and then rupture, forming a crusty yellowish-brown mass.
Pruritus is common, leading to scratching and spread of the infection.
Topical antibiotics may be used in the early stages, but systemic antibiotic treatment is necessary if the lesions are extensive. Unfortunately, the number of antibiotic-resistant strains of S. aureus is on the rise.
Bacterial Infections: Acute Necrotizing Fasciitis
Although a mix of aerobic and anaerobic bacteria is present at the site, the rapid course of infection and tissue necrosis (often referred to as “flesh-eating disease”) seems to be caused by a highly virulent strain of gram-positive group A beta-hemolytic Streptococcus (such as S. pyogenes that is responsible for necrotizing fasciitis).
Often acute necrotizing fasciitis is preceded by minor trauma to or infection of the skin and subcutaneous tissue of an extremity.
Systemic toxicity develops, manifesting as fever, tachycardia, hypotension, confusion, disorientation, and, in some cases, organ failure.
Treatment consists of aggressive antimicrobial therapy, fluid replacement, and excision of all infected tissue, including, if needed, amputation. Delayed treatment results in greater tissue loss, higher likelihood of amputation, and a higher mortality rate.
Bacterial Infections: Leprosy
Leprosy is caused by Mycobacterium leprae and in the past has infected millions of people worldwide. Since the organism is not highly contagious, extended contact with a source is required for infection to occur.
Leprosy is a chronic disease that affects skin, peripheral nerves, mucosa of the upper respiratory tract, and eyes.
Disease classified as either: paucibacillary—limited disease, fewer widespread lesions, or multibacillary—widespread with significant lesions and tissue damage.
Leprosy is curable, and treatment in the early stages can avert disability.
Multidrug treatment has been made available by WHO to all patients worldwide, resulting in a significant decrease in the disease.
Viral Infections: Herpes Simplex (Cold Sores)
is the most common cause of cold sores or fever blisters, usually occurring in facial area (see illustration); herpes simplex type 2 (HSV-2) infections are usually limited to genital area (genital herpes). The two types have similar effects.
The primary infection may be asymptomatic, but the virus remains latent in sensory nerve ganglions.
Recurrence may be triggered by the common cold, sun exposure, or stress. An initial tingling is followed by the development of painful vesicles that rupture and form crusts.
Spread of the infection, either on the same individual or to others, occurs by way of direct contact with the fluid from the lesion.
Complications include the spread of the virus to the eye, resulting in keratitis.
The acute stage, viral shedding, and spread of infection may be reduced with the use of antiviral drugs (acyclovir or valacyclovir) either topical or systemic.
Viral Infections: Verrucae (Warts)
Warts (verrucae) are the result of a common infection with human papillomavirus (HPV). Many types of HPVs are associated with a variety of diseases.
The virus is transmitted by direct contact with an individual or a fomite such as a towel. Autoinoculation, resulting in the spread of warts, is also possible.
Warts are common in children and young adults but may resolve spontaneously within several years.
Warts appear in various shapes and locations, but the most common ones being the plantar type (as seen in illustration), caused by HPV types 1 through 4.
Genital warts (caused by HPV types 6 and 11) are associated with cervical cancer.
Treatment may include application of salicylic or lactic acid, freezing with liquid nitrogen, electrodessication, or laser surgery.
