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