BIOL164BIOL164

HumanBiologyHumanBiologyChCh44BodyOrganiza8on,Homeostasis,IntegumentBodyOrganiza8on,Homeostasis,Integument

Reminder:levelsoforganiza8onReminder:levelsoforganiza8on

• 4basic(ssuetypes:

• Epithelial

• Connec(ve

• Muscular

• Nervous

(Ch. 2)

(Ch. 4)

(Ch. 3)

Epithelial8ssueEpithelial8ssue

• Coversbodysurfaces

• Lineshollowcavi(esandorgans

• Formsglands

Connec8veConnec8ve8ssue8ssue

• Protectsandphysicallysupportsorgans

• Physio‐logicallysupportsorgans

• E.g.blood(nutrients,immunity)

• Storesfat

Muscle8ssueMuscle8ssue

• Contractstomovethebodyandtomovesubstancesthroughthebody

Nervous8ssueNervous8ssue

• Conductsnerveimpulsesfromonepartofthebodytoanother

• Fast‐ac(ngcommunica(onandcontrol

• =neurons(nervecells)+neuroglia(suppor(ngcells)

Reminder:levelsoforganiza8onReminder:levelsoforganiza8on

The slides that followintroduce the 11 majororgan systems anddescribe the mainfunctions of each

HomeostasisHomeostasis

• Literalmeaning:“samestanding”

• =body’smaintenanceofarela1velyconstantinternalenvironment

• despitechangesintheexternaland/orinternalenvironment

• Goalistoachievestateofdynamicequilibrium(=balance)ofinternalcondi(ons

• E.g.bloodpressure,bodytemperature,hormonelevels,etc.

• Homeostasisismaintainedbythebody’scontrolsystems

• whichu(lizenega(vefeedbackmechanisms:

• Nervoussystem–rapid,short‐term,specific;viaelectricalimpulses

• Endocrinesystem–slower,longer‐las(ng,widespreadeffects;viahormones

(chemicals)

homeosta8ccontrolsystemhomeosta8ccontrolsystem

• Theeffector’sresponsemay:

• Oppose/negates(mulus(nega8vefeedback)

• Mostcommon(andshownhere)

• Enhance/exaggerates(mulus(posi8vefeedback)

• Rareinbody

change = stimulus

1.

2.

3.

integrates =compares stimulusto set point

Homeosta8ccontrolofbodyHomeosta8ccontrolofbodytemperaturetemperature

IntegumentaryIntegumentarysystemsystem• =theskinanditsderiva(ves(hair,nails,sweatglands,oilglands)

• Somefunc(ons:

• Protec8on

• Physicalbarriertoabrasion,chemicals,UVradia(on,microbes,water

loss,etc.

• Containsimmunecellstofightinfec(on

• Excre8onofsalts,wastes,water

• Bodytemperatureregula8onviainsula(on,sweatevapora(on,

vasodila(on/constric(onofbloodvesselstotheskin

• VitaminDsynthesis–forcalciummetabolism

• Sensoryrecep8onfortouch,pressure,pain,temperature

• Lipidenergystorage(subcutaneousadipose)

Skin(Skin(cutaneouscutaneousmembrane)membrane)• 2mainlayers:

• 1.Epidermis–kera(nizedstra(fiedsquamousepithelium

• 2.Dermis–looseanddenseCTthatcontainsbloodvessels,nerves,sweatandoilglands,hairfollicles,etc.

• Nottechnicallypartoftheskin:

• Hypodermis(a.k.a.subcutaneouslayerorsuperficialfascia)–looseCTandadipose

MoreontheepidermisMoreontheepidermis• Mostofthecellsarekera8nocytesthatmaketheproteinkera8n(tough,waterproof)

• Constantlymito(catbo^om,fla^enanddieaspushedtowardsurface,and

eventuallysloughoff

• Fromforma(ontoshedding:2weeksto1month

• Someofthecellsaremelanocytesthatmakethepigmentmelanin

• protectsagainstUVrays,maininfluenceonskincolor,differentcolorsanddarkness

gene(callydetermined

Skinderiva8vesSkinderiva8ves

• Derivedembryonicallyfromepidermis

• Eventhoughmaynolongerbelocatedinepidermis

• Theyinclude:

• Hairandhairfollicles

• Oil(sebaceous)glands

• Sweatglands

• Nails

• Teeth(Ch.15)

HairHair• Hairs–nonlivingcolumnsofkera(nproducedbyhairfolliclesthatareembeddedwithin

dermis

• Associatedwith:

• Oilglands–produceoil/sebum(moredetailsoon)

• Arrectorpilimuscles–erecthair,cause“goosebumps”

• Nerveendings–sensoryreceptorsforlighttouch

• Func(ons:

• ShieldscalpfromUV

• Cushion(very)lightblowtothehead

• Insulatescalp

• Sensa(on(lighttouch)

• Blockpar(cleentrye.g.eyelashes,earandnosehairs)

Oil(sebaceous)glandsOil(sebaceous)glands

• Foundeverywhere

• exceptpalmsofhandsandsolesoffeet

• mostconnectedtohairfollicles

• Secretesebum:

• alipid‐basedproduct

• moisturizes,lubricates,andsodens

hairandskin

• preventskera(nfrombecoming

bri^le

• helps“waterproof”skin

• inhibitsbacterialgrowth

Oilglands,hairfollicles,andacneOilglands,hairfollicles,andacne

SweatglandsSweatglands• 2‐5millioninadults;adults>children,men

typically>women

• Locatedalmosteverywhere,butmostdenseon

palmsandsoles

• Producesweat:99%water;alsocontainssalts

organicnutrients,nitrogenous

wastes

• Func(ons:

• Thermoregula1onviaevapora(ve

cooling

• Excre1onofsalts,urea,uricacid,amino

acids,sugars,lac(cacid,andmore!