Bio 201: Integumentary System
Bio 201: Integumentary System BIO 201
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This 18 page Class Notes was uploaded by ASUNursing19 on Friday February 26, 2016. The Class Notes belongs to BIO 201 at Arizona State University taught by Dr. Penkrot in Winter 2016. Since its upload, it has received 192 views. For similar materials see Human Anatomy/Physiology I in Biology at Arizona State University.
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Date Created: 02/26/16
The Integumentary System Skin and subcutaneous tissue o Functions of the skin o Epidermis and dermis o Hypodermis (subcutaneous tissue; fat in most people) o Thick and thin color o Skin color o Skin markings Hair and nails Cutaneous glands Skin disorders Overview Integumentary System : consists of the skin and its accessory organs o Hair, nails, and cutaneous glands Most visible system so attention paid to this organ system Inspection of the skin, hair, and nails is significant part of a physical exam Skin is the most vulnerable organ o Exposed to radiation, trauma, infection, and injurious chemicals Receives more medical treatment than any other organ system Dermatology: scientific study and medical treatment of the integumentary system Skin and Subcutaneous Tissue The body's largest and heaviest organ 2 o Covers area of 1.52.0 m o 15% of body weight (more if you include hypodermis) Consists of two layers: o Epidermis: stratified squamous epithelium o Dermis: connective tissue layer Hypodermis : another connective tissue layer below the dermis Most skin is 12 mm thick Ranges from 0.5 mm on eyelids to 6 mm between shoulder blades Thick skin: on palms and sole, and corresponding surfaces on fingers and toes o Has sweat glands, but no hair follicles or sebaceous (oil) glands o Epidermis 0.5 mm thick Thin skin : covers rest of the body o Epidermis about 0.1 mm thick o Possess hair follicles, sebaceous glands and sweat glands Functions of the Skin Resistance of trauma and infection o Keratin and desmosomes o Acid mantle Other barrier functions o Waterproofing o UV radiation o Harmful chemicals Vitamin D synthesis o Derived from cholesterol o Skin first step o Liver ad kidneys complete process Sensation o Skin is our most extensive sense organ Thermoregulation o Thermoreceptors o Vasoconstriction / vasodilation Nonverbal communication o Acne, birthmark, scar Transdermal absorption o Administration of certain drugs steadily though thin skin adhesive patches Epidermis Epidermis : keratinized stratified squamous epithelium o Dead cells at the surface packed with tough protein: atin o Lacks blood vessels (vascular ) o Depends on the diffusion of nutrients from underlying connective tissue o Sparse nerve endings for touch and pain ** FOR EXAM: know EACH layer of the epidermis, it's order, and each layer's function ** Cells of Epidermis Five types of cells of the epidermis o Stem cells (basal cells) Undifferentiated cells that give rise to keratinocytes In deepest layer of epidermis (stratum basale) o Keratinocytes Great majority of epidermal cells Synthesize keratin o Melanocytes Occur only in stratum basale Synthesize pigment melanin that shields DNA form ultraviolent radiation Branched process that spread among keratinocytes o Tactile cells (Merkel cells) In basal layer of epidermis Touch receptor cells associated with dermal nerve fibers o Dendritic cells (Langerhans cells) Macrophages originating in bone marrow that guard against pathogens Found in stratum spinosum and granulosum Stand guard against toxins, microbes, and other pathogens that penetrate skin Stratum Basale A single layer of cuboidal to low columnar stem cells and keratinocytes resting on the basement membrane o Melanocytes and tactile cells are scattered among the stem cells and keratinocytes Stem cells of stratum basale divide o Give rise to keratinocytes that migrate toward skin surface o Replace lost epidermal cells Stratum Spinosum Consists of several layers of keratinocytes Thickest epidermal stratum in most skin o In thick skin, exceeded in thickness by stratum corneum Deepest cells remain capable of mitosis (mitosis occurs in stratum basale) o Cease dividing as they are pushed upward Produce more and more keratin filaments which causes cell to flatten o Higher up in this stratum, the flatter the cells appear Dendritic cells found throughout this stratum Named for artificial appearance created in histological section o Numerous desmosomes and cell shrinkage produces spiny appearance Strata Granulosum o Consists of 3 to 5 layers of flat keratinocytes o Contain coarse darkstaining keratohyalin granules Lucidum o Seen only in thick skin (palms and soles) o Thin translucent zone superficial to granulosum o Keratinocytes are densely packed with eleidin Makes skin somewhat transparent o Cells have no nucleus or other organelles o Zone is featureless with indistinct boundaries Stratum Corneum Up to 30 layers of dead, scaly, keratinized cells Form durable surface layer o Surface cells flake off (exfoliate) Resistant to abrasion, penetration, and water loss Life History of Keratinocytes Keratinocytes are produced deep in the epidermis by stem cells in stratum basale o Some deepest keratinocytes in stratum spinosum also multiply and increase their numbers Mitosis requires an abundant supply of oxygen and nutrients o Deep cells acquire from blood vessels in nearby dermis o Once epidermal cells migrate more than two or three cells away from the dermis, their mitosis ceases Newly formed keratinocytes push the older ones toward the surface In 3040 days a keratinocyte makes its way to the skin surface and flakes off o Slower in old age, faster in skin injured or stressed Calluses or corns: thick accumulations of dead keratinocytes on the hands or feet Cytoskeleton proliferates, cells shoved upward, cells grow flatter Produce lipidfilled membranecoating vesicles (lamellar granules ) In stratum granulosum three important developments o Keratinocyte nucleus and other organelles degenerate, cells die o Keratohyalin granules release a protein filaggrin Binds the keratin filaments together into coarse, tough bundles o Membranecoating vesicles release lipid mixture that spreads out over cell surface and waterproofs it (important so we aren't constantly dehydrated) Epidermal Water Barrier Epidermal water barrier : forms between stratum granulosum and stratum spinosum Consists of: o Lipids secreted by keratinocytes o Tight junctions between keratinocytes o Thick later of insoluble protein on the inner surfaces of the keratinocyte plasma membranes Critical to retaining water in the body and preventing dehydration Cells above the water barrier quickly die o Barrier cuts them off from nutrients below o Dead cells exfoliate (dander) o Dandruff: clumps of dander stuck together by sebum (oil); you can see o Dander: you cannot see Dermis Dermis: connective tissue layer beneath the epidermis Ranges from 0.2 mm (eyelids) 4 mm (palms and soles) Composed mainly of collagen with elastic fibers, reticular fibers, and fibroblasts Well supplied with blood vessels, sweat glands, sebaceous glands, and nerve endings Hair follicles and nail roots are embedded in dermis Smooth muscle (piloerector muscles) associated with hair follicles o Contract in response to stimuli, such as cold, fear, and touch goosebumps Dermal papillae : "eggcrate" extensions of the dermis o Friction ridges on fingertips that create fingerprint patterns Papillary layer: superficial zone of dermis o Thin zone of areolar tissue in and near the dermal papilla o Allows for mobility of leukocytes and other defense cells should epidermis become broken o Rich in small blood vessels Reticular layer : deeper and much thicker layer of dermis o Consists of denseirregular connective tissue o Stretch marks (striae) : tears in the collagen fibers caused by stretching of the skin due to pregnancy or obesity o Tough layer used to make leather o Cleavage (tension) lines in reticular layer are caused by many collagen fibers running parallel to skin surface Externally invisible Important to surgeons because incisions parallel to cleavage lines heal more rapidly Hypodermis Subcutaneous tissue More areolar and adipose than dermis Pads body and binds skin to underlying tissues Drugs introduced by injection o Highly vascular and absorbs them quickly Subcutaneous fat o Energy reservoir o Thermal insulation o 8% thicker in women Skin Color Melanin: most significant factor in skin color o Produced by melanocytes o Accumulate in the keratinocytes of stratum basale and stratum spinosum o Eumelanin (true melanin) : brownish black o Pheomelanin: a reddish yellow sulfurcontaining pigment People of different skin colors have the same number of melanocytes o Dark skinned people Produce greater quantities of melanin Melanin granules in keratinocytes more spread out than tightly clumped Melanin breaks down more slowly Melanized cells seen throughout the epidermis o Light skinner people Melanin clumped near keratinocyte nucleus Melanin breaks down more rapidly Little seen beyond stratum basale o Amount of melanin also varies with exposure to ultraviolet (UV) rays of sunlight Other Factors in Skin Color Hemoglobin : red pigment of red blood cells o Adds reddish to pinkish hue to skin Carotene: yellow pigment acquired from egg yolks and yellow/orange vegetables o Concentrates in stratum corneum and subcutaneous fat The Infamous SprayTan Some contain carotenoids, lycopene o Actually can help prevent UV damage like melanin can o Can last a long time (months) DHAbased o Chemical reactions with dead keratinocytes o UV exposure right after application can cause free radical production o Fades quickly (days) Bronzers o Temporary only, can wash off like makeup Abnormal Skin Colors Cyanosis : blueness of the skin form deficiency of oxygen in the circulation blood o Airway obstruction (drowning or choking) or lung diseases (emphysema), COPD o Cold weather or cardiac arrest Erythema : abnormal redness due to dilated cutaneous vessels o Exercise, hot weather, sunburn, anger, or embarrassment Pallor : pale color when limited blood glow allows dermal collagen to be visible o Emotional stress, low blood pressure, circulatory shock, cold, anemia Albinism : recessive genetic lack of melanin that results in white hair, pale skin, and pink eyes from nonfunctional tyrosinase Jaundice : yellowing of skin and sclera due to excess of bilirubin in blood from compromised liver function o Bilirubin overflows into the bloodstream and then becomes visible in the skin Hematoma: (bruise) mass of clotted blood showing through skin Vitiligo Ideopathic (= don't completely understand what the cause is) death/dysfunction of melanocytes o Autoimmune causes, virus, neural stress, …? Can happen to persons of any ethnicity, but much more visible in darkerskinner individuals Diagnosis done with a black light Can be improved with a combination of topical steroids and UV light exposure Evolution of Skin Color Skin color: one of the most conspicuous signs of human variation Results from combination of evolutionary selection pressures o Especially differences in exposure to ultraviolet radiation (UVR) UVR has two adverse effects: o Causes skin cancer o Breaks down folic acid needed for normal cell division, fertility, and fetal development Folic acid: important for women because it is important in fetal development UVR has a desirable effects: o Stimulates synthesis of vitamin D necessary for dietary calcium absorption Populations native to the tropics/high altitudes and their descendants tend to have well melanized skin to screen out excessive UVR Populations native to far northern or southern latitudes where the sunlight is weak, tend to have light skin to allow for adequate UVR penetration Ancestral skin color is a compromise between vitamin D and folic acid requirements Women have skin averaging about 4% lighter than men o Need greater amounts of vitamin D and folic acid to support pregnancy and lactation High altitude and dry air increases skin pigmentation o Andes, Tibet, Ethiopia UVR accounts for up to 77% of variation in human skin color Other exceptions: o Migration, cultural differences in clothing and shelter o Intermarriage of people of different geographic ancestries o Darwinian sexual selection : a preference in mate choice for partners of light or dark complexion NTD Neutral Tube Defect Thought to be enhanced in pregnant and prepregnant women in folate deficiency Spina bifida, encephalocele (back of the skull never closed), anencephaly (no brain) Argyria Silver colloid as a "full spectrum antibiotic" leads to permanent silver crystal deposition Skin Markings Friction ridges: the markings on the fingertips that leave oily fingertips on surfaces we touch o Everyone has a unique pattern formed during fetal development and remain unchanged throughout life o Not even identical twins have identical fingertips o Allow manipulation of small objects Flexion lines (flexion creases): lines on the flexor surfaces of the digits, palms, wrists, elbows o Marks sites where the skin folds during flexion of the joints Freckles and moles : tan to black aggregations of melanocytes o Freckles are flat, melanized patches o Moles (= nevus) are elevated melanized patches often with hair Moles should be watched for changed in color, diameter, or contour May suggest malignancy (skin cancer) Hemangiomas (birthmarks): patches of discolored skin caused by benign tumors of dermal blood capillaries o Angio = blood vessels o Some disappear in childhood others last for life o Capillary hemangiomas, cavernous hemangiomas, portwine stain Simian Line & Retardation Transverse palmar line o Correlated with some forms of mental developmental problems but not definitive! Mongolian Spots 9095% incidence in East Africans 8590% incidence in Native Americans 5070% incidence in Hispanics 0.12% incidence in Caucasians Some may result from melanocytes becoming trapped in reticular layer of dermis during development o Usually gone by 35 years of age, almost always by puberty Hair and Nails Hair, nails, and cutaneous glands are accessory organs of the skin Hair and nails are composed of mostly of dead, keratinized cells o Pliable soft keratin (soft and can bend easily) makes up stratum corneum of skin o Compact hard keratin makes up hair and nails Tougher and more compact due to numerous crosslinkages between keratin molecules Pilus : another name for hair (pili plural of pilus) Hair: a slender filament of keratinized cells that grows from an oblique tube in skin called a hair follicle Distribution of Human Hair Hair is found almost everywhere on the body except: o Palms and soles o Ventral and lateral surface and distal segment of fingers and toes o Lips, nipples, and parts of genita2s Limbs and trunks have 5570 hairs per cm o Face and scalp about 10x as much o 100,000 hairs on an average person's scalp o Number of hairs does not differ much from person to person or even between sexes Types of Human Hair Three kinds of hair grow over the course of our lives o Lanugo : fine, downy, unpigmented hair that appears on the fetus in the last three months of development o Vellus: fine, pale hair that replaces lanugo by time of birth Two thirds of the hair of women Onetenth of the hair on men All of hair of children except eyebrows, eyelashes, and hair of the scalp o Terminal : longer, coarser, and usually more heavily pigmented Forms eyebrows, eyelashes, and the hair of the scalp After puberty, forms the axillary and pubic hair Male facial hair and some of the hair on the trunk and limbs Structure of Hair and Follicle Hair is divisible into three zones along its length o Bulb: a swelling at the base where hair originates in dermis or hypodermis Only living hair cells are in or near bulb Hair matrix in the bulb is the only part of the hair that allows for growth o Root : the remainder of the hair in the follicle o Shaft: the portion above the skin surface Dermal papilla : bud of vascular connective tissue encased by bulb o Provides the hair with its sole source of nutrition Hair matrix : region of mitotically active cells immediately above papilla o Hair's growth center Three layers of the hair in cresssections from inside out o Medulla : core of loosely arranged cells and air spaces o Cortex: constitutes the bulk of the hair Consists of several layers of elongated keratinized cells o Cuticle: composed of multiple layers of very thin, scaly cells that overlap each other Free edges directed upward Structure of Hair Follicle Follicle: diagonal tube that dips deeply into dermis and may extend into hypodermis o Epithelial root sheath Extension of the epidermis that lies immediately adjacent to hair root Toward deep end widens into bulge a source of stem cells for follicular growth o Connective tissue root sheath Derived from dermis and surrounds epithelial root sheath Denser than adjacent connective tissue Hair receptors are nerve fibers that entwine each follicle that respond to hair movement Piloerector muscle (arrector pili) are bundles of smooth muscle Hair Texture and Color Texture : related to differences in crosssectional shape o Straight hair is round o Wavy hair is oval o Curly hair is relatively flat Color : due to pigment granules in the cells of the cortex o Brown and black hair is rich in eumelanin o Red hair has a slight amount of eumelanin but a high concentration of pheomelanin o Blond hair has an intermediate amount of pheomelanin and very little eumelanin o Gray and white hair results from scarcity of melanin in the cortex and the presence of air in the medulla Mites Demodex folliculorum o May be parasitic or commensal o Live around hair follicles, especially on the face Large infestation: demodicosis o More common as we age 25% of 20 year olds Almost 100% by age 80 Hair Growth and Loss Hair cycle: consists of three developmental stages 1. Anagen: growth stage: 90% of scalp follicles at any given time Stem cells multiply and travel downward Pushing dermal papilla deeper into skin forming epidermal root sheath Root sheath cells directly above dermal papilla form the hair matrix Sheath cells transform into hair cells synthesize keratin, and die as they are pushed upward New hair grows up the follicle, often alongside of an old club hair form the previous cycle 2. Catagen: degenerative stage: mitosis in the hair matrix ceases and sheath cells below the bulge die The follicle shrinks and the dermal papilla is drawn up toward the bulge Base of hair keratinizes into a hard club, and hair now known as club hair Loses its anchorage Easily pulled out by brushing 3. Telogen: resting stage: when papilla reaches the bulge Club hair may fall out during catagen o Or pushed out by new hair in the next anagen phase We lose about 50100 scalp hairs daily In young adults the scalp follicles spend: o 68 years in anagen, 23 weeks in catagen, 23 months in telogen Hair growth : scalp hairs grow at a rate of 1 mm per 3 days (1018 cm/yr) Alopecia: thinning of the hair or baldness Pattern baldness : the condition in which hair loss from specific regions of the scalp rather than thinning uniformly o Combination of genetic and hormonal influence o Baldness allele is dominant in males and expressed only in high testosterone levels o Testosterone causes terminal hair in scalp to be replaced by vellus hair Hirsutism : excessive or undesirable hairiness in areas that are not usually hairy Functions of Hair Most hair on trunk and limbs is vestigial o Little present function o Warmth in ancestors Hair receptors alert us of parasites crawling on skin Scalp helps retain heat Gender identification Pubic and axillary hair signify sexual maturity and aids in transmission of sexual scents Guard hairs ( vibrissae): guard nostrils and ear canals Eyelashes and eyebrows o Nonverbal communication 5.6 Nails Scalelike modifications of epidermis that contain hard keratin Act as a protective cover for distal, dorsal surface on fingers and toes Consist of free edge, nail plate and root Nail bed is epidermis underneath keratinized nail plate Nail matrix : thickened portion of bed responsible for nail growth Nail folds : skin folds that overlap border of nail Eponychium: nail fold that projects onto surface of nail body o Also called cuticle Hyponychium: area under free edge of plate that accumulates dirt Nails normally appear pink because of underlying capillaries o Lunule : thickened nail matrix, appears white Abnormal color or shape can be an indicator of disease Cutaneous Glands The skin has five types of glands o Merocrine sweat glands o Apocrine sweat glands o Sebaceous glands o Ceruminous glands o Mammary glands Sweat Glands (Sudoriferous) Two kinds of sweat (sudoriferous glands) o Merocrine (eccrine) sweat glands Most numerous skin glands 3 to 4 million in adult skin Are simple tubular glands Watery perspiration that helps cool the body Myoepithelial cells: contract in response to stimulation by sympathetic nervous system and squeeze perspiration up the duct o Apocrine sweat glands Occur in groin, anal region, axilla, areola, bearded area in mature males Ducts lead to nearby hair follicles Produce sweat that is thicker, milky, and contains fatty acids Scent glands that respond to stress and sexual stimulation Develop at puberty Pheromones : chemicals that influence the physiology of behavior of other members of the species Bromhidrosis : disagreeable body odor produced by bacterial action on fatty acids Sweat Sweat: beings as a proteinfree filtrate of blood plasma produced by deep secretory portion of gland o Potassium ions, urea, lactic acid, ammonia, and some sodium chloride remain in the sweat, most sodium chloride reabsorbed by duct o Some drugs are also excreted in sweat o On average, 99% water, with pH ranged of 4 to 6 Acid mantle: inhibits bacterial growth o Insensible perspiration: 500 ml per day Does not produce visible wetness of skin o Diaphoresis : sweating with wetness of the skin Exercise: may lose one liter of sweat per hour Sebaceous Glands Sebum : oily secretion produced by sebaceous glands Flaskshaped glands with short ducts opening into hair follicle Holocrine glands : secretion consists of brokendown cells o Replaced by mitosis at base of gland Keeps skin and hair form becoming dry, brittle, and cracked o Eaten by bacteria,Demodex mites Lanolin : sheep sebum Ceruminous Glands Found only in external ear canal Their secretion combines with sebum and dead epithelial cells to form earwax (erumen ) o Keep eardrum pliable o Waterproofs the canal o Kills bacteria o Makes guard hairs of ear sticky to help block foreign particles from entering auditory canal Simple, coiled tubular glands with ducts that lead to skin surface Mammary Glands Breasts (mammae) of both sexes contain little glandular material o Release milk by apocrine process Mammary glands : milkproducing glands that develop only during pregnancy and lactation o Modified apocrine sweat gland Mammary ridges or milk lines o Two rows of mammary glands in most mammals o Primates kept only anterior most glands Additional nipples (polythelia) o May develop along milk line o Polymastia : additional developed breasts Skin Diseases Most vulnerable organ to injury and disease o Skin disease common in old age Dermatitis: inflammation (symptom, not a disease) Ringworm : fungal infection Tinnea fungal family Seborrheic dermatitis: recurring patches of scaly white and/or yellow inflammation Warts : viral infection o Human papilloma virus or HPV Acne Inflammation of sebaceous glands Affects 80% of teenagers and many adults Male sex hormones stimulate sebaceous glands to increase in size and hypersecrete Microorganisms feed on glycerol from sebum causing inflammation and plugging glands o Comedos : whiteheads o Open comedo (blackhead): dark due to lipid oxidation Treatment o Frequent cleansing, topical ointments o Accutane: drug that inhibits sebum production Eczema Many forms Most common is atopic eczema o Genetic component o Allergic reaction triggered by irritants, environment, stress NOT CONTAGIOUS Mild case dry, hot, uritis (itchy) Severe case broken, raw, bleeding No cure o Outbreaks may become less frequent with age Treated with o Emollients, topical steroids Psoriasis Immunemediated skin disease Genetic component NOT CONTAGIOUS Abnormal epithelial growth o Normal cell: ~30 days o Psoriasis: 35 days Dead cells create a white, flaky layer over the patch of inflamed skin Plaque psoriasis (psoriasis vulgaris) is the most common form Psoriatic arthritis, psoriatic nail dystrophy are less common forms Impetigo Bacterial HIGHLY CONTAGIOUS Tinea Fungal infections that eats keratin If on the skin and raised: ngworm If on the genitals: jock itch If on the head: tinea capitis If on the feet: athlete's foot Tinea Versicolor Known by many names o Sun Fungus o Haole Rot Fungus (yeast) infection of skin, 28% of adolescents have it Causes hypo or hyperpigmentation NOT the same as vitiligo 2/26/16 12:06 PM UVA, UVB & Sunscreens UVA & UVB o "Tanning rays" (UVA) and "burning rays" (UVB) o Both can burn as well as tan (so always protect against both) o UVB is used for vitaminD synthesis Both thought to initiate skin cancer As sale of sunscreens has risen so has skin cancer (correlative or causative?) o Those who use have higher incidence of basal cell o Chemical in sunscreen damage DNA and generate harmful free radicals PABA, zinc oxide, and titanium dioxide Skin Cancer Skin cancer : induced by ultraviolet radiation o Most often on the head and neck o Most common in fairskinned people and the elderly o One of the most common cancers, but easiest to treat o Has one of the highest survival rates if detected and treated early o Three types of skin cancer named for the epidermal cells in which they originate Most skin tumors are benign and do not metastasize A crucial risk factor for nonmelanoma skin cancers is the disabling of the p53 (DNA protector protein) gene Newly developed skin lotions can fix damaged DNA Determination of Skin Cancer The ABCDE Rule o A: Asymmetry; the two sides of the pigmented area do not match o B: Border is irregular and exhibits indentations o C: Color (pigmented area) is black, brown, tan, and sometimes red or blue o D: Diameter is larger than 6 mm (size of a pencil eraser) o E: Elevation is 3 mm higher than the skin surface Basal Cell Carcinoma Arises from cells of stratum basale and invades dermis, slow growing Treated by surgical removal and radiation (99%) Least likely form of skin cancer to metastasize Squamous Cell Carcinoma Arise from keratinocytes form stratum spinosum Lesions usually appear on scalp, ears, lower lip, or back of the hand Chance of recovery good with early detection and removal, but can metastasize to lymph nodes Malignant Melanoma Most deadly skin cancer Arises from melanocytes of a preexisting mole ABCD: Asymmetry, Border irregular, Color mixed & Diameter over 6 mm (Elevation) Highly metastatic, & resistant to chemotherapy Burns Burns: leading cause of accidental death o Fires, kitchen spills, sunlight, ionizing radiation, strong acids or bases, or electrical shock o Deaths result primarily from *fluid loss*, infection and toxic effects of eschar burned, dead tissue debridement removal of eschar Classified according to the depth of tissue involvement o Firstdegree burns: partial thickness burn involve only the epidermis Marked by redness, slight edema, and pain Heal in a few days Most sunburns are first degree burns o Seconddegree burns: partial thickness burn involved the epidermis and part of the dermis Leaves part of the dermis intact Red, tan, or white Two weeks to several months to heal and may leave scars Blistered and very painful o Thirddegree burns: full thickness burn the epidermis and all of the dermis, and often some deeper tissues (muscles or bones) are destroyed Often require skin grafts Needs fluid replacement and infection control Causes of burns: hot water, sunlight, radiation, electric shock or acids and bases Causes of deaths: fluid loss, infections, effects of dead tissue (eschar) Degrees of burns o 1st degree: only epidermis (red, painful, edema) o 2nd degree: epidermis, part of dermis (blistered) o 3rd degree: epidermis, dermis and more Treatment: fluid replacement and infection control o IV proteins, nutrients, and fluids Skin Grafts & Artificial Skin Thirddegree burns require: Graft options o Autograft : tissue from different region of patient o Isograft: skin from identical twin o Cultured keratinocyte patches Temporary graft options o Homograft (allograft) : from unrelated person o Heterograft (xenograft) : from another species o Amnion from an afterbirth o Artificial skin from silicone and collagen Rule of Nines Estimates the severity of burns Burns considered critical if: o Over 25% of the body has seconddegree burns o Over 10% of the body has thirddegree burns o There are thirddegree burns on face, hands, or feet
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