Figure 5.1 Epidermis Hair shaft Dermis Reticular layer Papillary layer Hypodermis (superficial...

Figure 5.1

Epidermis

Hair shaft

Dermis Reticularlayer

Papillarylayer

Hypodermis(superficial fascia)

Dermal papillae

Pore

Subpapillaryvascular plexus

Appendagesof skin • Eccrine sweat gland• Arrector pili muscle• Sebaceous (oil) gland• Hair follicle• Hair rootNervous structures

• Sensory nerve fiber• Pacinian corpuscle• Hair follicle receptor (root hair plexus)

Cutaneous vascularplexus

Adipose tissue

Chapter 5: Integument System

Integument System

• Skin and its derivatives – sweat and oil glands, hair, and nails

• Skin – Covers entire body– 1.2 2.2 square meters– ~4 – 5 kg, 9-11 lbs– ~ 75 of total body weight– Thickness varies – 1.5 4.0 mm thick– 2 regions –

• dermis – tough, leathery material, vascularized fibrous connective tissue

• Epidermis – epithelial cells, outermost protective shield

Skin

• Epidermis• Dermis• Hypodermis

– Also called superficial fascia– Not part of skin– But same protective feature– Mostly adipose tissue– Anchors skin to underlying structures– Loosely so that skin can slide freely over structures– Shock absorber/insulator– Thickens when gain weight– Women – accumulates in thighs and breasts first– Men – anterior abdomen “beer belly”

Figure 5.1

Epidermis

Hair shaft

Dermis Reticularlayer

Papillarylayer

Hypodermis(superficial fascia)

Dermal papillae

Pore

Subpapillaryvascular plexus

Appendagesof skin • Eccrine sweat gland• Arrector pili muscle• Sebaceous (oil) gland• Hair follicle• Hair rootNervous structures

• Sensory nerve fiber• Pacinian corpuscle• Hair follicle receptor (root hair plexus)

Cutaneous vascularplexus

Adipose tissue

Epidermis

• Keratinized stratified squamous• 4 distinct cell types• 4 or 5 layers• Cells:

1. Keratinocytes2. Melanocytes3. Epidermal dendritic cells4. Tactile cells

Keratinocytes

• Most common• Produce keratin – fibrous protein that helps give

epidermis its protective function• Arise from cell layer – stratum basale• Continuous mitosis – epidermal growth factor• Push cells upward by production of new cells• By the time they reach the surface – dead, scale

like structures with a keratin filled plasma membrane

Keratinocytes

• Millions of dead cells rub off everyday• Totally new epidermis every 25 – 45 days• Friction – hands and feet – accelerated• Persistent friction – causes thickening of

epidermis - callus

Melanocytes

• Spider shaped epithelial ells that synthesize melanin

• Found in deepest layer of epidermis• Melanin – made and accumulated in

membranous granules• Melanosomes – moved to ends of melanocyte

processes, then taken up by keratinocytes• Pigment – protects nucleus from damaging

effects of UV radiation

Epidermal Dendritic Cells

• Also called Langerhorn cells• Arise from bone marrow and migrate to

epidermis• Ingest foreign substances• Key activators of the immune system• Slender processes extend around

keratinocytes – forming continuous network

Tactile (Merkel) Cells

• Present in epidermal junction• Shaped like spiky hemisphere• Associated with disk like sensory nerve ending• Sensory receptor for touch

Layers of Epidermis

• Variation – thick or thin skin• Thick skin – covers – palms, fingers, soles• 5 layers or strata– Stratum basale – DEEP– Stratum spinosum– Stratum granulosum– Stratum lucidum– Stratum corneum – superficial

Figure 5.2a

Dermis

Stratum corneumMost superficial layer; 20–30 layers of deadcells represented only by flat membranoussacs filled with keratin. Glycolipids inextracellular space.Stratum granulosumThree to five layers of flattened cells,organelles deteriorating; cytoplasm full oflamellated granules (release lipids) andkeratohyaline granules.Stratum spinosumSeveral layers of keratinocytes unified bydesmosomes. Cells contain thick bundles ofintermediate filaments made of pre-keratin.Stratum basaleDeepest epidermal layer; one row of activelymitotic stem cells; some newly formed cellsbecome part of the more superficial layers.See occasional melanocytes and epidermaldendritic cells.

(a)

Layers of Epidermis

• Thin Skin – covers rest of body• Stratum lucidum – absent • Outer strata thinner

Figure 5.2b

MelanocyteMelanin granule

Tactile(Merkel) cell

Sensorynerve ending Epidermal

dendritic cell

Dermis

KeratinocytesStratum corneumMost superficial layer; 20–30 layers of dead cells represented only by flat membranous sacs filled with keratin. Glycolipids in extracellular space.Stratum granulosumThree to five layers of flattened cells, organelles deteriorating; cytoplasm full of lamellated granules (release lipids) and keratohyaline granules.Stratum spinosumSeveral layers of keratinocytes unified by desmosomes. Cells contain thick bundles of intermediate filaments made of pre-keratin.Stratum basaleDeepest epidermal layer; one row of actively mitotic stem cells; some newly formed cells become part of the more superficial layers. See occasional melanocytes and epidermal dendritic cells. Desmosomes

(b)

1. Stratum Basale

• Basal layer• Also called stratum germinative ‘germinating

layer”• Deepest epidermal layer• Attached by wavy borderline• Single row of stem cells• Many mitotic nuclei• 10- 25 % of cells – melanocytes • Occasional tactile cells

2. Stratum Spinosum

• Prickle layer• Several cell layers thick• Web like system of intermediate filaments• Tension resisting bundles of pre-keratin filaments• Span cytosol and attach to desomones• Keratinocytes – have spines – called prickle cells• Artifacts that arise during tissue prep• Scattered are melanin granules and epidermal

dendritic cells

3. Stratum Granulosum

• Granular layer• 3 to 5 cell layers in which keratinocytes – appearance

changes• Keratinization – cells fill with protein keratin• Cells flatten, nuclei and organelles begin to disinigrate• Accumulate 2 types of granules:

– Keratohylane granules – help to form granules– Lamellated granules – water resistant glycolipids, slow water loss

across epidermis• Plasma membrane thickens as cytosol proteins bind• Lipids released – coat outer surface• Make more resistant to destruction

4. Stratum Lucidum

• Clear layer• Appears – thin translucent• 2 or 3 rows of clear, flat, dead keratinocytes

with distinct boundaries• Arrogate in large, cable like parallel arrays• Visible in only thick skin

5. Stratum Corneum• Horney layer• Broad zone of 20-30 cell layers thick• ¾ of total thickness• Keratin and thickened plasma membrane of cells – protect skin

against abrasion and penetration• Glycolipids – water proof• Durable overcoat• Protects deeper cells from – air, water-loss, and chemical,

biological, and physiological assaults• Layer of dead cells – play many roles• Remnants – cornified or horney cells• Average person – sheds 18 kg in lifetime• Outer skin we see - DEAD

Dermis

• 2nd major skin region• Strong, flexible connective tissue• Connective tissue proper cells – fibroblasts,

macrophages, mast cells, and WBCs• Semi fluid matrix – binds together like a stocking• “hide” – like animal hide• Richly supplied with nerve fibers, blood, and lymphatic

vessels• Major portion of hair follicles, sweat, and oil glands

found here

Dermis

• 2 layers – 1. Papillary layer – - thin, superficial areolar connective tissue- Fine, interlacing collagen and elastic fibers from loosely

woven mat- Numerous small blood vessels- Dermal papillae – superior surface- Peg like projections- Indent overlying epidermis - House fee nerve endings - pain receptors - touch receptors – Meissner’s Corpuscles

Dermis

• Papillary layer – cont• Palms of the hands and soles of the feet• Papillae lie atop larger mounds – dermal ridges• Turn overlying epidermis into epidermal ridged

(mounds)• Friction ridges – increased friction and enhanced

gripping ability• Genetically determined and unique to each• Sweat pores – open at crest• Sweat = fingerprints

Figure 5.4a

Friction ridges

(a)

Openings ofsweat gland ducts

Dermis

2. Reticular Layer – deeper- 80 % of thickness of dermis- Coarse, irregularly arranged- Dense fibrous connective tissue- Cutaneous plexus – network of blood vessels- Extracellular matrix – adipose cells- Thick bundles of collagen fibers

Dermis2. Reticular Layer – deeper (cont)- Less dense regions – cleavage

or tension lines- Incisions made parallel to lines

– skin gapes less and heals better

- Gives skin strength- Keeps skin hydrated- Stretch recoil properties- Flexure lines – dermal folds –

occur near joints

Skin Color

• 3 pigments – melanin, carotene, and hemoglobin• Only melanin – made in skin• Melanin – polymer of tyrosine amino acids• 2 forms • Range in color from yellow tan and reddish

brown black• Synthesis depends on enzyme – tyrosine• Pigment found only in deeper layer of epidermis

Melanin

• Humans – differ in skin color• Not random – – Darker – near equator, need greater amount of

protection from the sun– Lighter – closer to poles, need less protection

• Melanocytes of darker skinned people produce more and darker melanocytes

• Freckles and pigmented nevu (moles) – local accumulation of melanin

Melanin

• Prolonged sun exposure – substantial melanin buildup

• Protects skin from UV radiation• Excessive sun – damages skin– Clumping of elastic fibers – leathery skin– Temporary depresses immune system– Alters DNA of skin cells – leads to skin cancer– UV radiation – also destroys folic acid stores – can be

harmful if pregnant – impaired development of fetal NS

Carotine

• Yellowish – orange pigment• Found in certain plant products – carrots• Accumulates in stratum corneum and fatty

tissue of hypodermis• Converted to vitamin A – essential for normal

vision• Infants - orangey

Hemoglobin

• Pinkish hew• Caucasian – small amounts of melanin –

hemoglobin color shows through

• Cyanosis – blue skin – hemoglobin poorly oxygenated– Heart failure and severe respiratory disorders– Darker skin – melanin masks, but can be seen in

mucus membranes and nail beds

Alterations in Skin Color

• Redness – erythema – embarrassment, fever, hypertension, inflammation or allergy

• Pallor – blanching – fear, anger, also signifies anemia or a decrease in BP

• Jaundice – yellow – liver disorder, yellow bile pigments accumulate in blood, deposited in body tissues

• Bronzing – Addison's Disease, adrenal cortex – inadequate amounts of steroid hormones, sign of pituitary gland tumor

• Black and Blue – burses, blood escaped circulation and clotted beneath skin, hematomas – blood swelling

Appendages of Skin

• Nails, sweat glands, sebaceous (oil) glands, hair follicles and hair

• Forming – appendages• Epithelial bud – formation• Stimulated by reduced production of cell

adhesion factor (cadherin)• Cell-cell attractions – broken, cells move and

rearrange themselves

Sweat (Sudoriferous) Glands

• Distributed over entire skin surface except nipples, and parts of external genitalia (tip of penis)

• Up to 3 million per person• 2 types – eccrine and apocrine• Myoepithelial cells – specialized cells – contract

when stimulated by NS• Contraction forces sweat into and through duct

system to surface

Eccrine Sweat Glands

• Merocrine sweat glands• Numerous• Most abundant in palms, soles of feet, and

forehead• Simple coiled tubular gland• Secretory part in dermis• Duct –open in a funnel shaped pore on skin

surface

Figure 5.5b

(b) Photomicrograph of a sectioned eccrine gland (220x)

Secretory cells

Dermal connectivetissue

Duct

Sebaceousgland

Sweat pore

Eccrinegland

Eccrine Sweat Glands

• Secretion – sweat• Hypertonic filtrate of the blood• Released by exocytosis

– 99 % water– Some salts (NaCl)– Vitamin C– Antibodies– Microbe killing peptide – dermcidin– Metabolic wastes (urea, uric acid, and ammonia)– Small amounts of ingested drugs

• Acidic pH 4.0-6.0

Eccrine Sweat Glands

• Sweating – • Regulated by sympathetic part of Autonomic

NS• Major role – prevent from overheating• Heat induced sweat begins at head and

spreads• Emotionally induced stress – begins at palms,

soles, and armpits

Figure 5.5b

(b) Photomicrograph of a sectioned eccrine gland (220x)

Secretory cells

Dermal connectivetissue

Duct

Sebaceousgland

Sweat pore

Eccrinegland

Apocrine Sweat Glands• Approximately – 2000 of them• Confined to auxiliary asnd anogential areas• Exocytosis • Larger than eccrine• Lie deeper in dermis and sometimes hypodermis• Ducts empty into hair follicles• Same basic components of sweat plus some fatty substances and

proteins• Viscous• Milky/yellowish color• When organic molecules are decomposed by bacteria – body odor

Apocrine Sweat Glands

• Begin functioning at puberty• Little role in thermoregulation, function not

yet known• Through of as the human equivalent of scent

glands• Increased activity during foreplay • Enlarge and recede with menstrual cycle

Apocrine Sweat Glands

• Ceruminous glands – modified apocrine glands

• Lining of internal ear canal• Secretion mixes with sebum• Sticky bitter substance – cerumen – earwax• Thought to deter insects and block entry of

foreign material

Apocrine Sweat Glands

• Mammary Glands – specialized sweat glands• Secret milk

Sebaceous (oil) Glands

• Oil glands• Simple branched alveolar glands• Found all over body except thick skin of palms

and soles• Small amounts on body trunk and limbs• Numerous on face, neck, and upper chest• Secrete – sebum- oily substances

Figure 5.5a

(a) Photomicrograph of a sectioned sebaceous gland (220x)

Sebaceousgland duct

Hair inhair follicle

Secretory cells

Dermalconnectivetissue

Sebaceousgland

Sweatpore

Eccrinegland

Sebaceous (oil) Glands

• Central cells – accumulate oil lipids• Engorged – burst• Holocrine glands• Develop from hair follicles• Sebum secreted into follicle – softens and lubricates

hair and skin– Slows water loss from skin– Bactericidal- bacteria killing

• Secretion - stimulated by hormones (androgens) activated during puberty

Sebaceous (oil) Glands

• When blocked – white head• When material inside oxidizes – becomes a

blackhead• Acne – active inflammation of sebaceous glands• Bacterial infection – staphylococcus

• Cradle cap – infants – seborrhea – fast flowing sebum

Hair and Hair Follicles

• Millions on skin except – palms, soles, nipples, and external genitalia (some parts)

• Warmth – mammals - ours less luxuriant and useful

• Main function – sense insects• Hair on scalp – prevent physical trauma, heat

loss, and sunlight• Eyelashes – shield eyes • Nose Hairs – filter large particles

Structure

• Hair (pili)• Flexible strands• Produced by hair follicles• Consist largely of dead keratinized cells• Hard keratin– 2 advantages

1. Tougher and more durables2. Individual cells do not flake off

Figure 5.6a

Hair shaft

ArrectorpiliSebaceousglandHair root

Hair bulb

(a) Diagram of a cross section of a hair within its follicle

• Connective tissue root sheath• Glassy membrane• External epithelial root sheath• Internal epithelial root sheath

Follicle wall

• Cuticle• Cortex• Medulla

Hair

(b) Photomicrograph of a cross section of a hair and hair follicle (250x)

• Connective tissue root sheath

Follicle wall

• Cuticle

• Glassy membrane

• Cortex• Medulla

• Internal epithelial root sheath

• External epithelial root sheath

Hair

Hair shaft

ArrectorpiliSebaceousglandHair root

Hair bulb

Figure 5.6b

Structure - Hair

• Regions1. Shaft – portion in which keratinization is

complete, extends halfway into skin2. Root – keratinization ongoing, portion of hair

deep in follicle- Shape

- Flat ribbon-like – hair kinky- Oval – silky and wavy- Perfectly round – straight and coarse

Structure - Hairs

• 3 layers – 1. Medulla– central core

- Large cells, air spaces- Contains soft keratin

2. Cortex – bulky layer- Surrounding medulla- Several layers of flattened cells

3. Cuticle – outer layer- Single layer of cells that overlap each other- Most heavily keratinized- Tends to wear away at tip – keratin fibrils – frizz out, spilt ends

Hair Pigment

• Made by melanocytes• Transferred to cortical cells• Different colors – yellow, rust, brown, black• Red hair – colored by iron containing pigment

– trichosiderin• Gray or white – decrease in melanin in

production

Structure of Hair Follicle

• Folded down from epithelial surface into dermis• May extend to hypodermis• ~ 4 mm below skin• Hair – bulb – expanded region at base• Hair follicle receptor – (hair plexus)• Wraps around bulb• Hair papilla – dermal tissue that protruded into hair bulb• Knots of capillaries – supply blood• Wall – connective tissue root sheath• Thickened basement membrane – glassy membrane• Epithelial root sheath – invagination of epidermis

Figure 5.6c

Hair shaft

ArrectorpiliSebaceousglandHair root Hair bulb

(c) Diagram of a longitudinal view of the expanded hairbulb of the follicle, which encloses the matrix

• Internal epithelial root sheath• External epithelial root sheath

• Connective tissue root sheathFollicle wall

Hair matrix

MelanocyteHair papilla

Subcutaneous adipose tissue

• Medulla• Cortex• Cuticle

• Glassy membrane

Hair root

Structure of Hair Follicle

• Hair Matrix – actively dividing area of hair bulb

• Originate in hair bulb• New cells produced, older cells pushed out• Arrector pili – smooth muscle • Contraction pulls hair upright• Dimples skin – goose bumps

(d) Photomicrograph of longitudinal view of the hair bulb in the follicle (160x)

Follicle wall

Hair matrix

Hair papilla

Subcutaneousadipose tissue

Hair root

• Connective tissue root sheath• Glassy membrane• External epithelial root sheath• Internal epithelial root sheath

• Cuticle• Cortex• Medulla

Hair shaft

ArrectorpiliSebaceousglandHair root

Hair bulb

Figure 5.6d

Types of Hair

• Vellus hair – pale, fine hair – body hair of children and women

• Terminal Hair – coarse, long hair – Eyebrows and scalp– Puberty – terminal appear is auxiliary and pubic

regions (both sexes), face and chest (male)

Hair Growth

• Dependent on - Nutrition and hormones• Poor nutrition = poor hair growth• Increased dermal blood flow – chronic physical

irritation = increased hair growth

• Undesired Hair growth – eliminated by electrolysis• Excessive hairiness in women – Hirsutism – can be

from adrenal gland or ovarian tumor that secretes large amounts of androgens

Rate of Growth

• Varies • Average ~ 2.5 mm/week• Growth cycles –

1. Active phase2. Regressive phase3. Resting phase

Rate of Growth

• Scalp – active 6 – 10 years before inactive for a few months

• Average – 90 hairs lost a day• Eyebrows are only active for ~ 3-4 months

Hair Thinning/Baldness

• Growth fastest – teens 40 years old - then slows• Hairs not replaced as fast as they are shed – Alopecia• True or frank baldness – Male pattern baldness –

genetically determined, sex influenced condition• Delayed action gene and changes in response of hair

follicles to DHT• Follicular growth very short• Minoxidial – drug that reduces BP, found to stimulate

hair growth• Finasteride – pill – must take everyday or new hair falls

out

Hair Thinning/Baldness

• Thinning – can be caused by:– High fever– Surgery– Emotional trauma– Drugs – excessive vitamin A

• Antidepressants• Anabolic steroids• Chemotherapy drugs

– Also protein deficiency or lactation– Alopecia Areata – condition where immune system

attaches follicles and hair falls out– Burns and radiation – can also cause permanent hair loss

Nails

• Scale like modification of epidermis• Clear protective covering• Correspond to hooves/claws of other animals• Tools – pick up and scratch• Hard keratin• Free edge, body, and root

Figure 5.7

Lateralnail fold

Lunule

Nailmatrix

Root of nail

Proximalnail fold

Hyponychium

Nail bed

Phalanx (bone of fingertip)

Eponychium(cuticle)

Bodyof nail

Free edgeof nail

(a)

(b)

Nails

• Nail bed – epidermis below nail• Nail Matrix – proximal part of nail bed,

responsible for nail growth• Pink – because of capillaries under dermis• Lunule – little moon – white crescent• Borders – overlapped by skin folds• Cuticle (eponychium) – proximal fold• Hyponychium – region below free nail,

accumulates dirt

Nails

• Yellow nails – indicate a respiratory or thyroid disorder

• Thickening and yellow – fungal infection• Outward concavity – iron deficiency• Horizontal lines – beaus lines – malnutrction

Functions of Integument System

• Protection• 3 types 1. Chemical Barrier – skin secretions and melanin- Low pH – acid mantle – retards bacteria growth- Seat/bacterialcide substances kill bacteria- Defensins – natural antibiotics secreted by skin- Cathelicidins – wounded skin secretes to prevent

infection- Melanin – protects against UV radiation

Functions of Integument System

• Protection2. Physical/Mechanical barriers – continuity of

skin- Hardness of keratinized cells- Water resistant – glycolipids – block diffusion

of water

Functions of Integument System• Protection2. Physical/Mechanical barriers (cont)- Some substances can penetrate skin –

1. Lipid soluble – oxygen, carbon dioxide, vitamin A, D, E, & K. and steroids2. Oleoresins - poison ivy/poison oak3. Organic solvents – acetone, paint thinner, etc.4. Salts of heavy metals – lead and mercury5. Selected drugs – nitroglycerine and nicotine6. Drug agents – penetration enhancers, ferry other drugs into body

- Enhanced by alcoholic drinks- Metals and organic solvents – can be lethal and can cause kidneys

to shut down- Also brain damage- Lead – anemia and neurological affects

Functions of Integument System

• Protection• Biological Barriers – • Dendritic cells – present antigens to WBCs• Macrophages – attack viruses and bacteria• DNA – chemical sunscreen, electrons absorb

UV radiation, convert it to harmless heat

Functions of Integument System

• Body temperature Regulation –• 31- 32 C – external– Sweat glands will produce ~ 500 ml of sweat a day

- Insensible perspiration • Body temperature increase – NS stimulates

blood vessels to dilate and sweat glands to secrete– Loss can be up to 12 L/day – sensible perspiration

Functions of Integument System

• Cutaneous Secretion – • Cutaneous sensory receptors – • Exteroceptors – respond to stimuli outside the body• Meissners Corpsules and tactile discs – feel of

clothing• Pacinian or purcles – bumps/contact involving

deeper pressure• Free nerve endings – painful stimuli, irritating

chemicals or extreme heat or cold

Functions of Integument System

• Metabolic Functions – • Sunlight – vitamin D precursor – converted to

vitamin D, role in calcium metabolism• Keratinocyte Enzymes –

1. ‘disarm” cancer causing chemicals2. Convert chemicals to carcinogens3. Activate steroid hormones: cortisol hydroxycortisone

- Skin makes biologically important proteins - collagenase

Functions of Integument System

• Blood reservoir – • Extensive and can hold large amounts of blood • ~ 5% of total blood volume• Constriction – moves blood to other organs

that need it

Functions of Integument System

• Excretion – • Limited amounts of nitrogen containing

wastes – ammonia, uric acid, urea• Perfect sweating – water and salt

Homeostatic Imbalances

• More than 1000 different conditions and aliments

• Bacterial, viral or yeast infections• Cancer and burns

Homeostatic Imbalances• Skin Cancer – • 1 in 5 Americans• Most are benign and do not spread• Wart – neoplasm caused by a virus• UV light – another risk factor

– Damages DNA bases– Adjacent bases fuse, forming lesions – dimers– Also disables tumor suppressor gene p 53

• Sunburn – increases production of Fas – a protein that causes genetically damaged skin cells to commit suicide, skin pealing after sunburn– Damages DNA bases– Adjacent bases fuse, forming lesions – dimers– Also disables tumor suppressor gene p 53

Homeostatic Imbalances – Skin Cancer

• Skin lotions – fix damaged DNA before cells develop into cancer cells

• Contain oily vesicles – liposomes – enzymes that initiate repair of DNA mutation

Homeostatic Imbalances – Skin Cancer

• Basal Cell Carcinoma – • Least malignant• Most common• 80 % of skin cancers• Stratum basal cells proliferate –

invade dermis and hypodermis• Lesions occur most often in face• Shinny dome shaped nodules• Later develop an ulcer• Slow growing• Surgical excision

Homeostatic Imbalances – Skin Cancer

• Squamous Cell Carcinoma • 2nd most common• Arises from keratinocytes

of stratum spinosium• Scaly red papule• Small, rounded elevation• Most often on head and

hands• Grows rapidly and

metastasize if not removed

Homeostatic Imbalances – Skin Cancer• Melanoma – • Cancer of melanocytes• Most dangerous• Highly metastatic• Resistant to chemo• 2 – 3 5 of all skin cancer• Increase rapidly• Most occur spontaneously• 1/3 develop in persisting moles• Spreading brown to black patch• Early detection needed• If over 4 mm thick – survival poor• Surgical removal and immunotherapy

Homeostatic Imbalances – Skin Cancer

• ABCD Rule – • A. Asymmetry – 2 sides don’t match• B. Border irregularity – borders exhibit indentations• C. Color – several colors – blacks, browns, tans,

blues, reds• D. Diameter – larger than 6 mm in diameter –

pencil eraser• Some want to add • E. elevation – elevation above skin

Homeostatic Imbalances – Burns

• Burns – • Tissue damage, inflicted by intense heat, electricity,

radiation, or certain chemicals• Denatures cell proteins• Causes cell death• Immediate threat – loss of body fluids renal shut

down shock• Rules of 9s – body divided into 11 areas– Each 9% of total area– Genitals – remaining 1 %

Figure 5.9

Anterior and posteriorhead and neck, 9%

4 1/2 %4 1/2 %

Anterior and posteriorupper limbs, 18%

Anterior and posteriorlower limbs, 36%

100%

Totals

Anterior and posteriortrunk, 36%

Anteriortrunk,18%

9% 9%(Perineum, 1%)

4 1/2 %

Homeostatic Imbalances – Burns

• Supplement nutrients – extra calories to replace damaged tissue

• After initial crisis passed – infection and sepsis next threats

• Bacterial, viral, and fungal infections

Homeostatic Imbalances – Burns

• Classified according to severity:1st degree burn – only epidermis is damaged.- Localized redness, swelling, and pain2nd degree burn – epidermis and upper regions of dermis- blisters, red painful3rd degree burn – full thickness of skin- Gray white/cherry red/blackened- Not painful – nerve endings destroyed- Skin graft needed – living bandage- Graft takes – extensive scar tissue

(a) Skin bearing partialthickness burn (1st and 2nd degree burns)

1st degreeburn

2nd degreeburn

Skin bearing fullthickness burn(3rd degree burn)

3rddegreeburn

Homeostatic Imbalances – Burns

• Critical if – • Over 25 % of body – 2nd degree burns• Over 10 % - 3rd degree burns• 3rd degree burns on head, face, and feet

Developmental Aspects of Integumentary System

• Epidermis develops from embryonic ectoderm• Dermis and hypodermis develop from mesoderm• By the end of the 4th month – skin fairly well formed• During 5th and 6th month fetus is covered with delicate

colorless hairs – lanugo coat• Shed by the 7th month, vellus hairs make appearance• Baby born – vernix caseosa – white substance produced

by sebaceous glands• Infancy and childhood – skin thickens• Older – skin thins