The Endocrine System PDF

The Endocrine System are s c 2 A q Endocrine Signaling In endocrinesignalinghormonessecretedi...

The Endocrine System are s c 2 A q Endocrine Signaling In endocrinesignalinghormonessecretedintoextracellularfluidbyendocrinecellsreachtargetcellsvia bloodstream FunctionsMaintaining homeostasismediateresponsestoenvironmentalstimuliregulategrowthand development triggersexualmaturityandreproduction Paracrine and Autocrine Signaling Manytypesofcellsproduceandsecretelocalregulatorsmoleculesthatactovershortdistances reachtheirtargetcellSoleyBYdiffusionandactonthemLocalregulatorsplayrole in BloodPressure regulationnervoussystemfunctionandreproductionLocalregulatorscanbeeitherParacrine Autocrine ParacrineTargetcelllieshearto asecretingcell Autocrine Targetcells are thesecretingcell  Synaptic and Neuroendocrine Signaling Ik endocrinesignaling neuronscalled heurosecreterycellssecreteneuro hormoneswhichdiffusefrom Hervecellendingsinto the bloodstreamManyneuro hormonesregulateendocrinesignaling  Classes of Hormones HormonesfallintothreemajorchemicalClassesPolypeptides steroids amines Cellular Hormone Response Pathways watersolublehormonesare secreted byexocytosis andtravelfreely inthebloodstream Being insolublein lipidstheycan'tdiffusethroughthePlasmamembranes oftargetcellsInstead these hormonesbindto cellsurfacereceptorsinducingchangesin cytoplasmicmoleculesand sometimes alteringgenetranscription LiPidSolublehormonesexitendocrinecellbydiffusingintothebloodstream Theythatbindtotransport ProteinsWhichkeepsthemsoluble inbloodThey diffuseintotargetcellsandtypicallybiled to receptors inthecytoplasm orthenucleusThehormoneboundreceptorthentriggerschanges in gene transcription Response Pathways to Water Soluble Hormones ThebindingofwaterSolublehormones to acell surfacereceptorproteintriggers acellularresponse Theresponsemaybeactivationof an eh2Mme achange of uptakeorsecretion of molecules rearranymentofthecytoskeleton Thechainofeventsthatconvertsthe extracellular chemical to a specificintracellularrespohseiscalledsignaltransduction  Response Pathways to Lipid Soluble Hormones ThehormoneactivatesthereceptorWhichthendirectlytriggersthe cell'sresponse In mostcases achange ingeneexpression Multiple Responses to A Single Hormone A hormonecanelicitdifferentresponses inParticulartargetcells if thosecellsdiffer inreceptor typeor in themoleculethatproducestheresponse Endocrine Tissues and Organs Someendocrinecells are found in organs as apart oftheorgansystemMoreoftenendocrine cellsaregroupedintoductlessorganscalled endocrineglandsEndocrineglandssecretehormones directlyintothesurrounding fluid exocrineglandshaveductsthatcarrysecretedsubstances such as sweat or salivaonto bodysurfaces orintobodycavities  Simple Endocrine Pathways In asimpleendocrinePathway endocrinecells respond directlyto an internal or external stimulusbysecreting aParticularhormone Thehormonetravels in thebloodstream to target cellswhereit interactswith its specificreceptors Simple Neuroendocrine Pathway Thestimulus is relievedBY a sensory neuron rather thanendocrinetissue Thesensory neuron in turnstimulates aneurosecretorycell Ik responsetheneurosecretorycell secretes aneuro hormoneLikeotherhormones theneurohonnohediffusesintothe bloodstreamandtravels to target cells Differenthormones can be cut off thesameproteinchainusing eh2Yines b 0h1Y amines Thelevels of hormone i b the bloodstream The secretion model Breakingdown rate protection by binding proteins Disposihy rate urine  Feedback Regulation NegativefeedbackResponsereducesthe initial stimulusThistypeof regulationpreventsexcessive pathwayactivity Positivefeedback Reinforces astimulusleading to agreater response Vertebrates Coordination oftheendocrinesignalingreliesheavilyon the hypothalamus Thehypothalamusrelieves informationfromHewesthroughout thebodyand in responseinitiatesneuroendocrinesignalingSignals fromthehypothalamus travelto thePituitarygland hypophysis locatedatthebase of thehypothalamus ThePituitary ismadeupoftwofusedglandsposterioranterior and performdifferentfunctions ThePosteriorPituitary is an extension of thehypothalamusHypothalamicaxons that reach into the Posteriorpituitarysecreteneurohormonessynthesized inthehypothalamus TheanteriorPituitaryis an endocrine gland that secreteshormones in response to hormones 5how the hypothalamus  Posterior Pituitary Hormones secretorycells of thehypothalamusSeh Nuevo thesitethetwoposteriorPituitaryhormones Antidiuretichormoneoxytocin Aftertraveling to thePosterior Pituitarythesehuerohormonesarestoredtobereleased in responseto nerveimpulsestransmittedby the hypothalamus ADH Vasopressin Regulateskidneyfunctionhelpingmaintainnormalbloodsoluteconceletratious social behavior OxytocinControlsmilksecretionregulatesuterine contraction duringbirthingmaternal care bondPair sexual activity Anterior Pituitary Hormones Controlsmetabolism Osimoregulation reproductionHormonessecreted bythe hypothalamus control therelease of all anteriorPituitaryhormonesThehypothalamushormonesarecalled releasing inhibiting hormones Thehypothalamicrealisingandinhibitinghormonesaresecretednearcapillaries atthebase of the hypothalamus Thecapillaries drain into short bloodVessies Called PortalVesslesWhich Subrideinto a second capillarynetwork intheanteriorpituitary hormone cascade  Parathyroid Hormone TheParathyroidglandregulatethe Ca levels17TH Parathyroidhormone raisesCa levels throughthebonesandkidneys17TH causes breakdown of themineral matrixin the bone releasing cat 17TH directlystimulates the uptake of Ca throughthe renaltubules PTHindirectlyraisesbloodlevels of Ca by promoting production ofvitaminD which in turn Stimulates the uptake of Ca 5tolu food If thelevels of Ca aretoohighthethyroid secretes calcitoninwhich inhibitsbonebreak downand enhances ca secretionBY thekidneys  Adrenal Hormones Located atopofthekidneyseach adrenalgland ismadeup oftwoglands with different celltypesfunctions Theadrenalcortex theouterportion theadrenal medulla thecentral PortionTheadrenalcortexconsistsof true endocrinecellswhereas the secretory cells of the adrenalIneduliadevelopfromneural tissue Role of Adrenal Medulla Triggers fightor flight by secreting epinephrine and norepinephrine both are considered catecholaminesCalmihesmadefromtyrosine 1 Role of Adrenal Cortex Theadrenalcortex becomesactiveunderstressfulconditionsthatincludelowblood Sugardecreasedblood Volumeand PressureAndShockSuchstimulicausesthehypothalamus to release a releasinghormoneto stimulatetheanteriorpituitaryto releaseACTH Which stimulates theadrenalcortextosecrete a family of steroids called corticosteroids Thetwo mainonesare GlucocorticoidsmineralCotticoids 4 Cortisol  Sex Hormones Sexhormonesaffectgrowthdevelopment reproductivecycles andsexualbehavior ThegonadsProducethreemajortypesofsteroidsexhormonesandrogens estrogens and Progesteron Allthreearefoundboth in maleandfemale Thetestes Primarilyproduceandrogensthemainonebeingtestosterone Ih humanstestfirst functionsbeforebirth PromotingmaledevelopmentAhdduringPuberty Estrogens ofwhichmostimportant isestradiolareresponsible for themaintenance of thefemale reproductivesystem andthedevelopment of femalecharacteristics In mammals progesterone isinvolved in Prepairing andmaintainingtissuesofthe uterus to supportthegrowthanddevelopment ofUhdembryo GnRH LH fsH Sexhormones Hormones and Biological Rhythms Metatohihe is Producedbythe pinealgland itsprimaryfunctionrelatestobiologicalrhythms associatedwithreproductionanddailyactivitylevels Melatonin is secretedat night Therelease OfInelatohihe is controlledby agroup of neuronsinthehypothalamuscalledSCNWhich functionsas a biological clock and relivesinputfromlightsensefive neurons in the retina of the eye