The Integumentary The Integumentary SystemSystemChapter 6Chapter 6

ObjectivesObjectives Identify the basic functions of the Identify the basic functions of the

integumentary systemintegumentary system Distinguish between the two layers of skin on Distinguish between the two layers of skin on

the basis of structure and functionthe basis of structure and function Identify the layers of the epidermis, and Identify the layers of the epidermis, and

describe the changes that occur in the cells as describe the changes that occur in the cells as they are pushed toward the surfacethey are pushed toward the surface

Discuss the role of the integumentary system in Discuss the role of the integumentary system in regulating body temperatureregulating body temperature

FunctionsFunctions ProtectionProtection

forms physical barrier to prevent loss of forms physical barrier to prevent loss of body fluids, damage from physical injury or body fluids, damage from physical injury or uv light, keeps out microorganismsuv light, keeps out microorganisms

Regulation of body temperatureRegulation of body temperature insulating barrier from external environmentinsulating barrier from external environment

CommunicationCommunication sensory receptors relay info to brainsensory receptors relay info to brain

Functions continuedFunctions continued Excretion of wastesExcretion of wastes

sweat glands get rid of metabolic wastesweat glands get rid of metabolic waste Vitamin D ProductionVitamin D Production

needed to help absorb calciumneeded to help absorb calcium calcium needed for bone growth and repair, calcium needed for bone growth and repair,

muscle contraction and nervous system functionsmuscle contraction and nervous system functions

The SkinThe Skin Primary organ of integumentary systemPrimary organ of integumentary system Two layersTwo layers

epidermisepidermis thin, superficial layer of epitheliumthin, superficial layer of epithelium

dermisdermis thicker, deep layer of connective tissuethicker, deep layer of connective tissue hypodermishypodermis

connection between skin and muscleconnection between skin and muscle

EpidermisEpidermis forms protective waterproof layerforms protective waterproof layer must constantly renew itselfmust constantly renew itself composed of five layerscomposed of five layers deepest to superficialdeepest to superficial

Stratum BasaleStratum Basale Stratum SpinosumStratum Spinosum Stratum GranulosumStratum Granulosum Stratum LucidumStratum Lucidum Stratum CorneumStratum Corneum

Stratum BasaleStratum Basalesingle layer of columnarsingle layer of columnar cellscellscapable of cell divisioncapable of cell division

newer cells pushnewer cells push older cells upwardolder cells upwardas they move towardas they move toward surface they losesurface they lose

their blood supplytheir blood supply and begin to dieand begin to die

Stratum SpinosumStratum Spinosummultiple layers of multiple layers of cuboidal cellscuboidal cellsattached to each otherattached to each other

by molecular bridgesby molecular bridgesspiny appearancespiny appearancedarkened nucleidarkened nuclei

first sign of deathfirst sign of deathinterstitial fluid no longerinterstitial fluid no longer

reaches these cellsreaches these cells

Stratum GranulosumStratum Granulosum

3-5 rows of partly3-5 rows of partlyflattened cellsflattened cells

cytoplasm has smallcytoplasm has smallgranules – proteinsgranules – proteinsin process of in process of becoming keratinbecoming keratin

keratin = waterproofingkeratin = waterproofingproteinprotein

Stratum LucidumStratum Lucidum

only found in thick skinonly found in thick skinpalms or soles of feetpalms or soles of feet

3-4 rows of flat, dead,3-4 rows of flat, dead,transparent cellstransparent cells

keratin formation keratin formation continuescontinues

Stratum CorneumStratum Corneum20-50 rows of flat,20-50 rows of flat,

dead cellsdead cellssloughed off and sloughed off and

replaced everyreplaced every3 weeks – 1 month3 weeks – 1 month

ghost cells containghost cells containkeratin but notkeratin but notabsolutely waterproofabsolutely waterproof

wrinkle after long bathwrinkle after long bathdue to osmosisdue to osmosis

Skin colorSkin color Melanocytes = special cells in between Melanocytes = special cells in between

stratum basalestratum basale secrete pigment – melaninsecrete pigment – melanin

dark colored proteindark colored protein more protein = darker skinmore protein = darker skin

everyone has same number of melanocyteseveryone has same number of melanocytes color determined by amount of melanin producedcolor determined by amount of melanin produced production regulated by genetic codeproduction regulated by genetic code skin color inheritedskin color inherited

Skin color continuedSkin color continued Melanin production modified by uv light Melanin production modified by uv light

exposure increases productionexposure increases production job is to absorb uv light so body is protected from harmful raysjob is to absorb uv light so body is protected from harmful rays excessive exposure – can’t keep upexcessive exposure – can’t keep up

results in sunburn & skin cancerresults in sunburn & skin cancer CaroteneCarotene

other pigment found in s. corneum & dermisother pigment found in s. corneum & dermis give yellowish hue = Asian peoplegive yellowish hue = Asian people

Blood vessels of dermis (Caucasians)Blood vessels of dermis (Caucasians) High number = pink to red skinHigh number = pink to red skin Low number = pale skinLow number = pale skin

Review QuestionsReview Questions What are the five major functions of the What are the five major functions of the

integumentary system?integumentary system? Why do cells die as they are pushed Why do cells die as they are pushed

farther away from the stratum basale?farther away from the stratum basale? What factors determine the color of your What factors determine the color of your

skin?skin?

DermisDermis Connective tissue underlying the Connective tissue underlying the

epidermisepidermis intercellular material made of collagenintercellular material made of collagen forms dense mat – like a wet spongeforms dense mat – like a wet sponge large supply of blood vesselslarge supply of blood vessels

¼ of blood located here¼ of blood located here nourishes cells and regulates temperaturenourishes cells and regulates temperature

Dermis continuedDermis continued Papillary regionPapillary region

superficial area adjacent to dermissuperficial area adjacent to dermis named for papillaenamed for papillae

fingerlike projectionsfingerlike projections interlock with epidermis strengthening layersinterlock with epidermis strengthening layers

responsible for fingerprints/footprintsresponsible for fingerprints/footprints papillae project into epidermis forming friction papillae project into epidermis forming friction

ridgesridges ridges help hand or foot grasp surface of objectsridges help hand or foot grasp surface of objects

Dermis continuedDermis continued Reticular regionReticular region

lies deep to papillary regionlies deep to papillary region gives dermis strength, gives dermis strength,

elasticity and extensibilityelasticity and extensibility if we lose these propertiesif we lose these properties

we get wrinkleswe get wrinkles

Accessory OrgansAccessory Organs Located in dermis but originated Located in dermis but originated

elsewhere = epidermal derivativeselsewhere = epidermal derivatives FunctionsFunctions

protection, communication, excretionprotection, communication, excretion ExamplesExamples

Hair, Sweat Glands, NailsHair, Sweat Glands, Nails

HairHair FunctionsFunctions

protects from injury from sunlight and foreign protects from injury from sunlight and foreign particlesparticles

follicle – supports hairfollicle – supports hair Two partsTwo parts

Root – surrounded by Root – surrounded by the folliclethe follicle

Shaft – part that extends Shaft – part that extends from the surfacefrom the surface

Hair continuedHair continued Grows similar to skinGrows similar to skin

Bulb provides nutrients to root and follicleBulb provides nutrients to root and follicle developing cells are indeveloping cells are in

bulb next to blood supplybulb next to blood supplypushed toward surfacepushed toward surfacecytoplasm replacedcytoplasm replacedby keratin – shaftby keratin – shaftmade of keratinmade of keratin

Grows 1mm/3daysGrows 1mm/3dayscontinues as long as cellscontinues as long as cellsare healthyare healthy

Lose 100/dayLose 100/dayNot replaced if follicles are Not replaced if follicles are damageddamagedHair color affected by melaninHair color affected by melanin

get old-no melanin-gray hairget old-no melanin-gray hair

Hair Follicle StructuresHair Follicle Structures Arrector Pili Arrector Pili

narrow band of smooth musclenarrow band of smooth muscle extends at angle from follicle to papillary regionextends at angle from follicle to papillary region pulls hair vertically whenpulls hair vertically when

you are cold or scaredyou are cold or scaredinsulator – gives offinsulator – gives off

heatheatpresses sebaceous presses sebaceous

gland and forces oilsgland and forces oilsto surface of skinto surface of skin

Hair Follicle StructuresHair Follicle Structures Sebaceous GlandsSebaceous Glands

oil glandsoil glands found all over skin except for palms and solesfound all over skin except for palms and soles secrete sebumsecrete sebum

water, fat, cholesterol,water, fat, cholesterol, protein and saltprotein and salt

keeps hair & skin soft keeps hair & skin soft and pliableand pliable

water resistant layerwater resistant layer production accelerated production accelerated

by sex hormonesby sex hormones ducts get clogged ducts get clogged

– – blackheads formblackheads form

Sweat GlandsSweat Glands Sudiferous GlandsSudiferous Glands

distributed throughout skindistributed throughout skin secrete sweat/perspirationsecrete sweat/perspiration FunctionsFunctions

maintain body tempmaintain body temp help kidneys eliminate help kidneys eliminate

metabolic wastemetabolic waste each gland is single tube, each gland is single tube,

tightly coiled in dermis or tightly coiled in dermis or hypodermishypodermis

Two typesTwo types EccrineEccrine ApocrineApocrine

Two types of sweat Two types of sweat glandsglands

EccrineEccrine functions throughout lifefunctions throughout life widely distributed through skinwidely distributed through skin secrete in response to high body tempsecrete in response to high body temp

ApocrineApocrine begin functioning during pubertybegin functioning during puberty secrete thick sweat containing proteinssecrete thick sweat containing proteins

these proteins promote bacterial growth on skinthese proteins promote bacterial growth on skin odor caused by microorganisms growing on skinodor caused by microorganisms growing on skin most active during periods of stressmost active during periods of stress most numerous in armpits and groinmost numerous in armpits and groin

NailsNails FunctionFunction

Protects end of fingers and toesProtects end of fingers and toes Helps pick up small stuffHelps pick up small stuff Grips floor as we walkGrips floor as we walk

Made of compressed Made of compressed epidermis and keratinepidermis and keratin

Nail bodyNail body visible surfacevisible surface

CuticleCuticle flap of stratum corneum flap of stratum corneum

overlying proximal edgeoverlying proximal edge of nailof nail

Nails continuedNails continued Nail rootNail root

contains active stratum basale contains active stratum basale Nail matrixNail matrix

pushes new cells outwardpushes new cells outward cells soon die and compresscells soon die and compress

LunulaLunula part of matrix seen part of matrix seen

through nailthrough nail Formation of keratin Formation of keratin

requires calciumrequires calcium no calcium – thin brittle nailsno calcium – thin brittle nails

ReceptorsReceptors Distal ends of nerve cellsDistal ends of nerve cells Act like antennae – receive info about worldAct like antennae – receive info about world Sensations travel to brain at 40m/sSensations travel to brain at 40m/s Three types of receptorsThree types of receptors

Pacinian Corpuscles Pacinian Corpuscles pressure changespressure changes

Meissner’s CorpusclesMeissner’s Corpuscles slight pressureslight pressure detects fine touchdetects fine touch

Nerve EndingsNerve Endings excessive temp and pressure changesexcessive temp and pressure changes detection of paindetection of pain

HypodermisHypodermis Lies deep to the skinLies deep to the skin Insulating barrier for deep structuresInsulating barrier for deep structures Connects skin to underlying structuresConnects skin to underlying structures

uses strands of collagen extending from uses strands of collagen extending from dermis through hypodermis to muscle layerdermis through hypodermis to muscle layer

Temperature Regulation Temperature Regulation on HOT Dayson HOT Days

Heat sensitive receptors in skin tell brain it’s too hotHeat sensitive receptors in skin tell brain it’s too hot Brain stimulates sweat glandsBrain stimulates sweat glands Body begins secreting sweatBody begins secreting sweat Brain signals blood vessels to dilateBrain signals blood vessels to dilate

relax and expandrelax and expand Blood flow to skin increasesBlood flow to skin increases Excess heat carried by blood escapes through skin to Excess heat carried by blood escapes through skin to

airair Sweat evaporates, cooling skin surfaceSweat evaporates, cooling skin surface Lower skin temp cools bloodLower skin temp cools blood Cooled blood travels to other parts of the body and Cooled blood travels to other parts of the body and

internal temp is loweredinternal temp is lowered

Temperature Regulation Temperature Regulation on COLD Dayson COLD Days

Receptors tell brain it’s too coldReceptors tell brain it’s too cold Brain tells blood vessels to constrictBrain tells blood vessels to constrict

reduces heated blood flowreduces heated blood flow reduces heat lost through skinreduces heat lost through skin

Brain tells skeletal muscles to contractBrain tells skeletal muscles to contract shiveringshivering arrectores pilorum = goose bumpsarrectores pilorum = goose bumps contractions arrector pili produces heatcontractions arrector pili produces heat

Other systems helping Other systems helping outout

If body temp is too highIf body temp is too high Cardiovascular SystemCardiovascular System

heart beats faster which pushes blood to the heart beats faster which pushes blood to the surface faster to be cooledsurface faster to be cooled

Respiratory SystemRespiratory System breathing rate increases so heat is carried out breathing rate increases so heat is carried out

when we exhalewhen we exhale