肾上腺超声

Chapter17AdrenalGlandTheadrenalglandsareorgansthatcontrolchronicandacutestress(急性应激)inthebodyby①regulatingbloodpressure,②heartrate,③bronchodilatation,④electrolytebalance,⑤andemergencybloodsugarlevels.Theadrenalglandsaresmallpeanut-shapedglandsthatsitcranialtobothleftandrightkidneyA,adrenalcortexTheadrenalcortexistheoutertissuelayerresponsibleforproducingdifferenttypesofsteroidsformaintenanceofbloodsugar,electrolytes,andsexsteroidproduction.1,Zonagranulosa(粒状带):Thisistheoutermostareaofthecortex,whichisresponsibleforproducingasteroidhormonecalledaldosterone,alsocalledamineralocorticoid(盐皮质激素).2,Zonafasciculata(束状带):Thislayeristheinnerregionofthead-renalcortexthatproducesaprednisone-likesteroidcalledcortisol(皮质醇).3,Zonareticularis(网状带):Thezonareticularisistheinnerregionoftheadrenalcortexthatproducesaprednisone-likesteroidcalledcortisol(皮质醇).B,adrenalmedullaTheadrenalmedullaisthesectionoftissueinthemiddleoftheglandthatisresponsibleforProducingepinephrine(肾上腺素)toassistthebodyinTimesofcrisisorlifeanddeathconcerns(fightorflight).B,adrenalmedullaEpinephrinehasthefollowingeffectsonthebody:●Increasesheartrate;●Increasesbloodvesselconstriction,thusincreasesbloodpressure;●Dilatesbronchialairways;●Decreasesintestinalsecretionandmovement;●Dilatestheeyes;AdrenalGlandIngeneral,theadrenalglandservesthebodyinthreefunctionstoaidinnormalmaintenanceandresponsetostress:1.Adrenalcortisolproduction,2.Adrenalmineralocorticoidproduction,3.andEpinephrineproduction.1,Adrenalcortisolproduction,1,Cortisolisproducedbytheadrenalcortextotakeproteinandfatandturnthemintoglucoseintimesoflowbloodsugar.Theprocessiscontrolledbyasmallglandinthebraincalledthepituitarygland,alsocalledthemastergland.Whenthebrainsenseslowbloodsugar,thepituitaryglandreleasesahormonecalledadrenocorticotropichormone(ACTH)tostimulatetheadrenalglandtoproducecortisol.ACTHisreleasedintothebloodstreamuntilitencountersspecificproteinreceptorsintheadrenalcortextostimulatethereleaseofcortisol.Cortisolisthenreleasedintothebloodstreamtostimulatethebreakdownofproteinandfatintosugar.Ascortisollevelsriseinthebody,thepituitarydecreasestheamountofACTHrelease.Thisiscalledanegativefeedbackloop.2,AdrenalmineralocorticoidproductionAdrenalMineralocorticoid(盐皮质激素)ProductionTheadrenalcortexalsoproducesamineralocorticoid()Calledaldosterone(醛固酮)thatisresponsibleforthereabsorptionofsodiumandexpulsionofpotassiumintheproximalconvolutedtubulesinthekidney.Thishormone,aboveallotheradrenalhormones,isneededfornormalhandlingofstressandbodymaintenance.Withoutsufficientlevelsofthishormone,ananimalcangetintoalife-threateningcrisis.●Itisnecessaryformaintenanceofthesodium/potassiumbalancewithinthebody.Sodiumistheelectrolytefoundinhighestconcentrationsintheserumandextracellularlyinthebody.Potassiumisfoundinthehighestconcentrationsinsidethecell.●Whenthebodyneedstoproduceanelectricalrhythmtoproducemuscularcontraction,nervedepolarization,heartcontraction,andmillionsofothermuscularandneurologicactivity,sodiumispumpedintracellularlyatthesametimepotassiumispumpedextracellularly.Thismovementofelectrolytesacrossthecellmembraneproducesanelectricalpotential(seeFigure17.3).●Whenthenormalsodiumandpotassiumlevelsareaffected,thebodyhasamoredifficulttimeproducingthenormalelectricalactivity,andthepetbecomesweakened,withmusclefasciculationsandabnormallyslowheartrhythms.Severelyaffectedanimalscanarriveinshockandlifethreatened.ThissyndromeiscalledanAddisoniancrisis(seebelow).3,EpinephrineproductionEpinephrineisproducedwhenananimalisthreat-ened,makingtheanimalreadytostandandfightortorun(flightorfightresponse).Thisreactionproducesthefollowingchangesinthebody:●Quickburstsofspeed●Increasedheartrate●Increasedbloodpressure●Bronchodilatationtoincreaseairflowintothelungs●Stoppingintestinalmovementandsalivation●DilationoftheeyesType1HyperadrenocorticismTherearethreeoverallmanifestationsofadrenaldiseasecommonlyseeningeneralpractice.Thefirstishypera-drenocorticism(Cushing’sdisease),whichisanoverpro-ductionofcortisolcausedbyaprimaryadrenalorpituitarydisease.HyperadrenocorticismTherearethreeoverallformsofthedisease:A.Pituitary-dependenthyperadrenocorticism(PDH);B.Adrenaltumor–neoplasiaC.IatrogeniccauseHyperadrenocorticismHyperadrenocorticismType2Hypoadrenocorticismhypoadrenocorticism(Addison’sdisease):whichisadecreasedproductionofaldosterone.Withthisdisease,thelackofaldosteroneinhibitsthebody’sabilitytoretainsodiumandexpelpotassium.Addison’sdiseasecanbeproducedbythefollowingdiseasesyndromes.1.Idiopathic(immune-mediated)hypoadrenocorticism2.Granulomatousdisease3.NeoplasiaType3pheochromocytoma(嗜铬细胞瘤)Thisadrenaline-producingtumorcanproduceseverehypertension,rapidheartrates,weakness,andeventuallydeath.MedicalHistoryAdrenalDisease1,HowOldIsthePet?Adrenaldiseaseisnotnecessarilyaproblemofoldageinanimals.However,adrenaldysfunctiontendstobeobservedinolderanimals.2IsThereBreedSpecificityforAdrenalDisease?●Hyperadrenocorticism(Cushing’sdisease):Caninebreedsthataremoresusceptiblearepoodles,dachshunds,Bostonterriers,boxers,and