Chapter 5

Integument FunctionsProtection

Barrier to microorganisms, abrasions, and water lossThermoregulation

Vasoconstriction or –dilation of blood vessels, Goose bumps or sweatFat and hair

SensationNerve endings to detect external stimuli throughoutMeissner’s corpuscles, Merkel discs, Pacinian corpuscles,

hair follicle receptors, and free nerve endingsMetabolic roles

Vitamin D from cholesterolProteins to deter wrinkles

ExcretionRemoves wastes from body (sweat)

Functional Organization of Integument

The Skin as an OrganLargest of the bodyAll 4 epithelial tissue types representedRanges in thickness

Thick (palms, fingertips, soles of feet)Thin (rest of body)

2 layersEpidermis is stratified squamous

4/5 layers and 4 cell typesDermis is dense irregular CT

Multiple cell types and accessory structures; 2 layers

Hypodermis not true integument Connective tissue and fat cells

Epidermal CellsKeratinocytes

Produce keratinJoined by desmosomesFormed deepDead at surface

Accelerated on feet/hands Calluses from constant

frictionMelanocyte

Produce melaninFormed deepKeratinocytes take up

Skin color due to activity not number

Tans signal DNA damage, fades as keratinocytes destroy

Epidermal Cells (cont.)Merkel cells

Touch sensitive cellsEpidermal/dermal border

Langerhans cellsPhagocytic cellsAssist immune system

responseFormed in bone marrow

Epidermal Layers Stratum basale

Single row, many nuclei Attached to basal lamina Some melanocytes and langerhans cells

Stratum spinosum Thick layers of ‘spiny’ keratinocytes Langerhans cells most abundant

Stratum granulosum Thin, 3-5 layers Keraticoytes fill w/ keratin Cell ‘toughen’ and die

Stratum lucidum Thin, translucent layer Only in thick skin Few, dead, densely packed keratinocytes

Stratum corneum 20-30 cells thick 14 days for cells to reach and remain 14 more

DermisFlexible and strong CTElastic, reticular, and collagen fibersFibroblasts, macrophages (WBC), and mast cells

(histamine)Tearing causes stretch marks (striae)Blisters when epi- and dermis separate by fluid-

filled pocket2 layers

Papillary layerReticular layer

Dermal LayersPapillary layer (20%)

Areolar CT Ridged surface projections

= dermal papillaEpidermal ridges

feet/palmsIncrease friction, enhance

grip, and fingerprints (sweat gland)

Contain pain and touch receptors (Meissner’s corpuscle)

Dense irregular CTAccessory structures Collagen fibers and adipose

Holds water = hydrationCleavage lines

Orientation related to skin stresses

Parallel cuts remain closed = faster healing

Right angles pulled open with recoil

Reticular layer (80%)

Skin ColorationMelanin is black, yellow-brown, or brown

Made by skin and stimulated by sunFreckles and moles are accumulations

Carotene is yellow to orange pigmentsAccumulates in st. corneum and fatty tissue in skinMost obvious where st. corneum thickest

Hemoglobin is crimson colored respiratory pigmentReduced blood supply turns skin whitePoorly oxygenated blood appears blue = cyanosis

Response to extreme cold or from respiratory disorders

Skin Color DisruptionsLeathery skin – clumping of elastin fibers from

excessive sun (cancer too)Redness – embarrassment, fever, inflammation or

allergyPallor/blanching – emotional distress, anemia, low

BPJaundice – liver disease, bile pigment depositionBronzing – hypofunctioning of adrenal cortex,

Addison’sBlack and blue – escaped blood clots in tissue,

hematomas

Sudoriferous (Sweat) GlandsAlmost everywhere Innervation contracts secretionEccrine sweat glands

Palms, soles, forehead Hypotonic blood filtrate released by

exocytosis Body cooling Emotional

Gland in dermis, duct into surface poreApocrine sweat glands*

Axillary and anogenital regions Secretions into hair follicle ducts Similar to sweat

Starts at puberty = body odorCeruminous

Cerumen (earwax)Mammary glands

Sebaceous (Oil) Gland Almost everywhere, but palms and solesHolocrine: collect and then burst, releasing

sebumSecreted onto hair follicle or into a pore

Softens hair and prevents water loss = brittle Sodium laureth sulfate

Lubricates skinAntibacterial function Disorders

Whitehead, blackhead, acne‘Cradle cap’Dandruff , seborrheic dermatitis

http://z.about.com/d/dermatology/1/0/p/6/Comedone_papule.jpg

HairOther mammals = warmthHumans = protection, sensation, filters

Few areas lack (palms, soles, lips)‘Hair’ (shaft and root) are dead, keratinized cells

Ribbonlike = kinky, oval = wavy, round = courseMatrix with 3 layers: medulla, cortex, cuticle

Follicle into dermis expands to bulbReceptors surroundPapilla w/ capillaries = nutrients

Arrector pili muscleHair pigment from melanocytes

NailsModified hard keratinized

epidermisProtect, grasp, and itch

Richly vascularizedFree edge, nail body (st. corneum),

nail bed (st. spinosum), and root (lunula)

Nail folds (lateral and proximal) extend = eponychium (cuticle)

Hyponychium (quick)

BurnsLoss of fluids renal shut down, denatured proteins

IV of fluids immediately Extra caloric intake

Sepis Protective role decreased after 24 hours Immune system done 1 -2 days after

Rule of nines 11 areas at 9% body (genitals 1%) Estimate

Classifying 1st degree: epidermal damage; redness and swelling (sunburn) 2nd degree: epidermis and upper dermis; blisters form

(cooking) 3rd degree: epidermis and dermis; gray-white/blackened, nerve

destruction Skin grafting