ExcretorySystemLESSON3

LearningGoals1. Howdoestheurinarysystemhelpmaintainhomeostasis?

2. Becomefamiliarwiththeanatomyofthekidneys

3. Listthecomponentsofanephronandtheirbasicroles

HomeostasisCellsmustregulatetheir:•ionicandpHbalance•Osmoticconcentration

WhenfacedwithWASTE,howdoesourbodyrespond?

Deamination•Removalofanaminogroup•By-product=ammonia•Ammonia+carbondioxide =urea•Eliminatedbythekidney

TheUrinarySystem•Regulatestheremovalofwaste•Mainorgans(1)kidneys(2)UrinarybladderButalsoincludestheuretersandurethra

Kidneys(1) RenalCortex(2) RenalMedulla(3) RenalPelvis

•Renalarteryà kidney•Bloodisfiltered•Kidneyà renalveins

Besidesurineformation…thekidneyisalsoinvolvedinregulating:

(1) Bloodvolumeandpressure(2) Electrolytebalance(3) BloodpH(4) RedBloodCellproduction

(Erythropoietin)

RedBloodCellProduction

TheNephron•Conservenutrientsandwater•Balanceions•Concentratewastes

>Interstitialfluid

3InterrelatedProcesses1)Filtration– fluidmovesfromthebloodintothebowman’scapsule

2)Reabsorption– transferssolutes/waterfromnephron,backintoblood

3)Secretion– removalofwastefromthebloodandinterstitialintothenephron

Whatdoesthispathwaylooklike?

Pathway

Afferentarteriolesà kidneyàglomerulus/Bowman’sCapsuleàProximalconvolutedtubuleà LoopofHenleà DistalCTàCollectingDucts

PathwayFiltration•Bloodentersthekidneyfromtheafferentarterioles•GlomerulusandBowman’scapsulefilterblood

PathwayReabsorption/Secretion•FiltratemovesthroughPCTwhereessentialsolutesandwaterarereabsorbedintotheperitubularcapillaries•DescendingportionoftheLoopofHenle,wherewaterisreabsorbed

Pathway

Reabsorption/Secretion•Ascendingportion,ionsareremoved•AttheDCT,additionalwaterandsaltsareremoved•Inthecollectingduct,additionalwater maybeabsorbed•Urineiscollectedintherenalpelvis,whereflowstothebladder tobestored

KeyPoint#1:Homeostasis?(1) Excretingwaste(2) Bloodvolumeandpressure(3) Electrolyte(ion)balance(4) BloodpH(5) RedBloodCellproduction(Erythropoietin)

KeyPoint#2:

KidneyAnatomy

KeyPoint#3:

Nephron&theexcretionpathway