LOM chap16 - skin

integumentary system: (2)

made up of skin, hair, nails, and glands

integument = covering, and skin is the outer covering for the body (weighs 8-10 lbs and extends over an area of 22 sq feet in average adults) and contains glands that secrete several fluids, nerves that carry impulses, and blood vessels that aid in the regulation of body temp

Skin functions: (4)

1. protective membrane over entire body and guards deeper tissues against excessive loss of water, salts, and heat, and against invasion of pathogens and their toxins (specialized cells - Langerhans cells - reacts to presence of antigens and initiates immune response)

2. contains sebaceous glands that produce sebum (oily secretion that lubricates) and sweat glands that produce sweat (watery secretion that cools as it evaporates) that pass through pores

3. nerve fibers under skin are receptors for sensations like pain, temperature, pressure, and touch, which helps body adjust to environment

4. tissues in skin maintain body temperature (thermoregulation) such as nerve fibers that carry messages to skin from brain that causes blood vessels to dilate to bring blood to surface and sweat glands to activate for cooling

3 layers of skin (from outer to in):

epidermis - thin, cellular membrane layer containing keratin

dermis - dense, fibrous, connective tissue layer containing collagen

subcutaneous layer - thick, fat-containing tissue

epidermis: (5)

outmost layer composed of squamous epithelium (cells are flat and scale-like), which is covering for both internal and external surfaces of body, and are arranged in several layers (stratum/strata) to form stratified squamous epithelium

lacks blood vessels, lymphatic vessels, and connective tissues (elastic fibers, cartilage, fat) = dependant on dermis for nourishment from capillaries (oxygen and nutrition)

deepest layer = basal layer

• contains melanocytes (contain pigment called melanin) - same amount in all people but different amounts of melanin

• where cells constantly grow and multiply and are the source of all other cells in epidermis (as they divide they’re pushed upward toward stratum corneum-most superficial layer-, where they shrink, flatten, lose nuclei, and die to become hard protein material called keratin - these cells called keratinocytes - within 3-4 weeks, process slows with age)

Dermis: [8]

beneath epidermis, composed of blood vessels, lymph and nerve fibers, hair follicles, sweat glands, sebaceous glands, connective tissue cells and fibers, interwoven elastin (protein that’s elastic and helps skin return to original position) and collagen fibers (fibrous protein in bone, cartilage, tendons, ligaments, and skin - tough and resistant + flexible - support and protect the blood and nerve networks passing through dermis)

Subcutaneous layer: (2)

specializes in formation of fat (adipocytes are predominant in this layer and they manufacture and store large quantities of fat) to protect deeper tissue of body, act as heat insulator, and energy storage

(epidermis and dermis are cutaneous layers)

Hair: (3)

hair fiber is composed of keratin and grows from hair follicles located in the dermis (deep cells in hair root produce keratinized cells that move up through hair follicles - sacs where hair fibers grow)

melanocytes located at root of hair follicle and donate melanin pigment to cells of hair fiber

hair color caused by eumelanin (darker black-brown pigment) and pheomelanin (lighter red-yellow pigment)

nails: (7)

hard keratin plates covering the dorsal surface of the last bone of each toe and finger, composed of keratinocytes

grows in thickness and length as result of division of cells in nail matrix at base of nail plate

lunula = whitish semilunar (half-moon shape) at base of nail plate (color from air mixed with keratin)

Cuticle = narrow band of epidermis (layer of keratin) at base and sides of nail plate

paronychium = soft tissue surrounding nail border

nail growth and appearance can alter during systemic disease

onycholysis = loosening of nail plate with separation from nail bed (can occur from with infection and often seen in psoriasis as pitting/depressions of nail plate due to inflammation)

sebaceous glands: (3)

sebaceous glands located in dermal layer over entire body (including hair follicles) except palms, soles (feet), and lips

secrete oily substance called sebum that contains lipids and lubricates the skin to minimize water loss

influenced by sex hormones that causes them them to hypertrophy at puberty (contributes to blackhead (comedo) formation and acne) and atrophy in old age

sweat glands: (4)

sweat glands (most common type = eccrine sweat glands) are tiny coiled glands found on almost all body surfaces (most numerous in palm and sole of feet) that originate deep in dermis and straighten out to extend through epidermis to surface through pores

sweat = almost pure water with dissolved materials like salt making up less than 1% - colorless and odorless but gathers bacteria that makes smell

controlled by sympathetic nervous system whose nerve fibers are activated by heart regulatory center in hypothalamic region in brain

apocrine sweat glands near in reproductive organs and armpits, secrete odorless sweat with substances easily broken down by bacteria on skin (milk-producing mammary gland is another type that secretes milk after childbirth)

albinism: (3)

individuals who are incapable of forming melanin, where skin and hair is white (can affect eyecolor)

oculocutaneous albinism = affects eyes, skin, and hair

ocular albinism = affects eyes only

collagen vascular diseases: (2)

affect connective tissues of the body

ex. scleroderma - immune system attacks and damages health tissue, leading to abnormal buildup of collagen and tight, thick skin

Melanin: (4)

skin pigment formed by melanocytes in epidermis (2 types: eumelanin and pheomelanin)

increases with exposure to strong UV light and creates suntan as protective response (sunburns when cannot absorb all UV rays - increased explore to sun causes wrinkles, permanent pigmentary changes, and cancer) - more melanin = less affected

darker skin = more eumelanin

lighter skin = more pheomelanin (doesn’t protect skin from UV rays as much)

adip/o, lip/o

fat

albin/o, leuk/o

white

caus/o

burn, burning

cauter/o

heat, burn

cutane/o, derm/o, dermat/o

skin

diaphor/o

profuse sweating

hidr/o

sweat or perspiration

erythem/o, erythemat/o

redness

ichthy/o

dry, scaly (fish-like)

kerat/o

hard

melan/o

black

myc/o

fungus (fungi include yeasts, molds, and mushrooms)

onych/o, ungu/o

nail

phyt/o

plant

pil/o, trich/o

hair

py/o

pus

rhytid/o

wrinkle

seb/o

sebum (oily secretion from sebaceous glands)

squam/o

scale-like

xanth/o, jaund/o, lute/o

yellow

xer/o

dry

anthrac/o

black (as coal) - 2

chlor/o

green

cirrh/o

tawny yellow

cyan/o

blue

eosin/o

rosy

erythr/o

red

poli/o

gray

lesion: (2) [10]

area of abnormal tissue on the body caused by disease or trauma (external forces)

ex. crust, cyst, erosion, fissure, macule, nodule, papule, pustule, ulcer, vesicle, wheal

crust: (2)

collection of dried serum and cellular debris (scab)

forms from the drying of a body exudate, as in eczema, impetigo, and seborrhea

cyst: (3)

thick-walled, closed sac or pouch containing fluid or semisolid material

pilonidal cyst - found over sacral area of back and contains hairs

epidermoid cyst - collection of yellowish, cheesy sebum commonly found on scalp, vulva, and scrotum

erosion: (2)

wearing away or loss of epidermis

don’t penetrate below the dermoepidermal junction, result of inflammation or injury and heal without scarring

fissure: (2)

groove or crack-like sore

anal fissure = break in skin lining of anal canal

macule: (2)

flat, pigmented lesion measuring less than 1 cm in diameter (freckles, tattoo marks, and flat moles)

patch = large macule, greater than 1 cm in diameter

nodule:

solid, round or oval elevated lesion 1 cm or more in diameter (enlarged lymph node, solid growths)

papule: (3)

small (less than 1 cm in diameter), solid elevation (bump) on the skin (acne)

skin tags = small benign growths usually attached to skin via a stalk (pedunculated

can become confluent (run together) and form plaques (elevated flat lesions)

pustule: (2)

papule containing pus

abscess = collection of buss

ulcer: (3)

open sore on thee skin or mucous membranes (deeper erosion)

decubitus ulcers (bedsores) = caused by pressure resulting from lying in one position

pressure ulcers involve loss of tissue, often seen in people with mobility disabilities

vesicle: (3)

small collection of clear fluid (serum); blister

forms after burns or with allergies/dermatitis

bulla (pl: bullae) = large vesicle greater than 1 cm

wheal: (2)

smooth, edematous (swollen) papule or plaque that is centraller redder than the surrounding skin (splotches)

can be papular (small area, ex. mosquito bite) or involve wide area (ex.allergic reaction), often accompanied by itching and seen in hives (urticaria), anaphylaxis, and insect bites

alopecia: (3)

absence of hair from areas where it normally grows (baldness)

can be hereditary (usually progressive), caused by disease, injury, or treatment (chemotherapy), or occurs with old age

alopecia areata = autoimmune disease where hair falls out in round patches without scarring/inflammation

ecchymosis (pl. ecchymoses): (2)

bluish-purplish mark (bruise) on skin

caused by hemorrhages into the skin from injury or leaking of blood from vessels

petechia (pl. petechiae): (2)

small, pinpoint hemorrhage (smaller versions of ecchymoses)

both ecchymoses and petechiae are forms of purpura (bleeding into the skin)

pruritus: (3)

itching (condition, not inflammation)

associated with dermatitis and other conditions

results from stimulation of nerves in the skin by substances released in allergic reactions or by irritation caused by substances in the blood or foreign bodies

acne (acne vulgaris): (4)

chronic papular and pustular (and cysts) eruption of the skin with increased production of sebum

blackhead = open comedo or comedone, sebum plug that partially blocks pore

whitehead = closed comedone, completely blocked pore where bacteria in skin breaks down sebum and produces inflammation in surrounding tissues

treatment = antibiotics/topical medication

bullous pemphigoid: (4)

rare autoimmune skin condition causing large, fluid-filled blister

occurs when autoantibodies attack proteins that hold together basal layer and dermis - they separate and form vesicles (bullae) on skin

rupture = erosions, erythema, and crusting seen on skin

treatment = topical corticosteroids creams/ointments (mild) or oral corticosteroid (Prednisone and drugs to suppress immune system)

burns: (4)

injury to tissue caused by heat contact (dry heat/fire, moist heat/steam or liquid, chemicals, lightning, electricity, radiation)

first-degree burns - superficial epidermal lesions, erythema, hyperesthesia, and no blisters

second-degree burns (partial-thickness burn injury) - epidermal and dermal lesions, erythema, blisters, and hyperesthesia more painful and sensitive to touch/air currents

third-degree burns (full-thickness burn injury) - epidermis and dermis are destroyed (necrosis of skin) and subcutaneous layer is damaged, leaving charred white tissue - would is insensate (patient doesn’t feel pain)

cellulitis: (3)

diffuse, acute infection of the skin marked by local heat, redness, pain, and swelling

abscess formation and tissue destruction can occur if appropriate antibiotic therapy isn’t given

areas of poor lymphatic drainage are susceptible to this skin infection

eczema (atopic dermatitis): (3)

inflammatory skin disease with erythematous, papulovesicular, or papulosquamous lesions (rash often begins on face, hands, elbow crease, or back of knees)

accompanied by intense pruritus and tends to occur in patients with history of allergies

treatment: corticosteroids and moisturizers

exanthematous viral disease: (4)

rash (exanthem) of the skin due to a viral infection

ex. rubella (German measles), rubeola (measles), and varicella (chickenpox)

erythema infectiosum = common exanthematous viral disease marked by fever and erythematous rash, caused by parvovirus

hand-foot-and-mouth disease = common viral illness in children, caused by an enterovirus

gangrene:

death of tissue associated with loss of blood supply

impetigo: (3)

bacterial inflammatory skin disease characterized by vesicles, pustules, and crusted-over lesions

contagious pyoderma usually caused by staphylococci or streptococci

treatment: antibiotics and proper cleasing of lesions

psoriasis: (4)

chronic, recurrent dermatosis marked by itchy, scaly red plaques covered by silvery gray scales

commonly involved forearms, knees, legs, and scalp

neither infection nor contagious (auto inflammatory disease), caused by increased rate of growth in basal layer of epidermis, can be hereditary

treatment (palliative - relieving not curing): topical lubricants, keratolytics, steroids, psoralen-ultraviolet A (PUVA) light therapy, and immunomodulators

scabies: (3)

contagious, parasitic infection of the skin with intense pruritus

affects areas like groin, nipples, and skin between fingers

treatment: topical medicated cream to destroy scabies mites (tiny parasites)

scleroderma: (3)

Chronic progressive disease of the skin and internal organs with hardening and shrinking of connective tissue (autoimmune disease)

Fibrous scar-like tissue forms in skin where it’s thick, hard, and rigid with depigmentation and hyperpigmentation, heart, lungs, kidneys, and esophagus may be affected too

treatment: palliative, immunosuppressive and anti-inflammatory agents, antifibrotics, and PT

systemic lupus erythematosus (SLE): (4)

Chronic autoimmune inflammatory disease of collagen in skin, joints, and internal organs

"butterfly" pattern of redness over the cheeks and nose

primarily in females (autoimmune disorder) - high levels of certain autoantibodies found in patient’s blood

treatment: corticosteroids and immunosuppressive drugs to control

discoid lupus erythematosus (DLE):

photosensitive, scaling, plaque-like eruption of the skin confined to the face, scalp, ears, chest, arms, and back, which heals with scarring

lupus vulgaris:

cutaneous form of tuberculosis

tinea: (6)

Infection of the skin caused by a fungus.

Tinea corporis (ringworm) = infection of ring-like pattern, highly contagious and causes severe pruritus

tinea pedis (athlete's foot) = affects skin between the toes

tinea capitis = on the scalp

tinea barbae = affecting the skin under a beard

tinea unguium = affecting the nails

urticaria (hives): (2)

Acute allergic reaction in which red round wheals develop on the skin

often reaction to food, animals, bug bites, pollen or medication, histamine released into bloodstream causing pruritus and edema (swelling)

vitiligo: (2)

Loss of pigment (depigmentation) in areas of the skin (milk-white patches)

form of leukoderma, associated with autoimmune disorders like thyroiditis, hyperthyroidism, and diabetes mellitus

callus: (3)

Increased growth of cells in the keratin layer of the epidermis caused by pressure or friction

common in feet and hands

corn (clavis) develops a hard core (whitish, cone-shaped central kernel)

keloid: (4)

Excess hypertrophied, thickened scar developing after trauma or surgical incision

result of excessive collagen in skin during tissue repair, extend beyond boundaries of original injury

treatment: excision, intralesional steroid injections, or ablative laser

cicatrix = scar left by a healed wound

keratosis: (3)

Thickened and rough lesion of the epidermis; associated with aging or skin damage

actinic keratosis = caused by long-term UV exposure, precancerous lesion that can evolve into squamous cell carcinoma

seborrheic keratosis = benign lesion resulting from overgrowth in upper epidermis, dark in color

leukoplakia: (2)

White, thickened patches on mucous membrane tissue of the tongue or cheek (evolves to squamous cell carcinoma)

precancerous lesion common in smokers, may be caused by chronic inflammation

nevus (pl. nevi) - moles: (2)

Pigmented lesion of the skin

dysplastic nevi = moles with atypical cells that can form called called melanoma

verruca (pl. verrucae): (6)

Epidermal growth (wart) caused by a virus

verruca vulgaris = common

plantar warts = soles of feet

juvenile warts = hands and face of children

venereal warts = genitals and around anus

removed with acids, freezing with liquid nitrogen (cryosurgery), or immune therapy, if virus remains = warts regrow

basal cell carcinoma: (3)

Malignant tumor of the basal cell layer of the epidermis

most common, almost never metastasizes

slow growing tumor occurring on chronically sun-exposed skin, especially near nose

squamous cell carcinoma: (5)

Malignant tumor of the squamous epithelial cells in the epidermis

can grow on any squamous epithelium surface (not just skin)

actinic keratosis (sun-related) = premalignant lesions in sun-damaged skin, can progress if not treated

advanced lesions = nodular and ulcerated

treatment = surgical removal, cryotherapy, electrodesiccation, curettage, radiotherapy

malignant melanoma: (7)

Cancerous growth composed of melanocytes

occur after prolonged exposure to sun in tanned or sunburned skin, biopsy required to confirm diagnosis

begins with dysplastic nevi on upper back, lower legs,arms, head, and neck

often metastasize to lungs, liver, bone, and brain

treatment = tumor excision, regional lymphadenectomy, immunotherapy, and drugs targeting B-RAF mutations

acral lentiginous melanoma = common in colored people in extremities

subungual melanomas = irregular, tan-brown longitudinal streak in nail

ABCDE’s of melanoma:

Asymmetry

Border (irregular)

Color (varies)

Diameter (larger than 6mm - pencil eraser)

Evolution (changes over time)

Kaposi Sarcoma: (2)

Malignant, vascular, neoplastic growth characterized by cutaneous nodules

common on arms and legs, range in color, one form of this condition is related to AIDS

bacterial analysis: (3)

Samples of skin are examined for presence of microorganisms

purulent (pus-filled) material or exudate (fluid that accumulates) often examined

can be strained to determine bacterial morphology and identification

fungal tests: (2)

Scrapings from skin lesions, hair specimens, or nail clippings are sent to a laboratory for culture and microscopic identification of fungal infection

treated with potassium hydroxide (KOH) preparation and examined microscopically - positive result = fungal infection

cryosurgery:

Use of subfreezing temperature achieved with liquid nitrogen application to destroy tissue

curettage:

Use of a sharp dermal curette to scrape away a skin lesion, shaped like spoon/scoop

electrodesiccation:

Tissue is destroyed by burning with an electric spark, used with curettage to remove cancerous lesions with well-defined borders

Mohs Surgery: (3)

Thin layers of malignant tissue are removed, and each slice is examined microscopically to check for adequate extent of the resection

specialized excision to treat basal cell carcinoma, squamous cell carcinomas, and other tumors

used where wide local excision cant work (face) or tissue sparing needed (large skin cancers)

Skin biopsy: (3)

Suspicious skin lesions are removed or sampled and examined microscopically by a pathologist

punch biopsy = removes core of tissue through a circular incision

shave biopsy = tissue cut with blade parallel to surface

skin test: (4)

Substances are injected intradermally or applied to the skin, and results are observed (to diagnose allergies and disease)

patch test = substances applied to the skin to identify allergic reactions

scratch test = substances scratched into the skin to observe reactions.

Schick test (for diphtheria), Mantoux and purified protein derivative (PPD) tests (for tuberculosis)

BCC:

basal cell carcinoma

bx

biopsy

derm

dermatology

DLE

discoid lupus erythematosus

PPD

purified protein derivative (skin test for tuberculosis)

PUVA:

psoralen-ultraviolet A light therapy (treatment for psoriasis and other skin conditions)

SCC

squamous cell carcinoma