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The Endocrine System Similar in fxn to the Nervous System Both send a message-Δ fxn of cell Nervous System-quick on, quick off Endocrine System-slow on,

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  • The Endocrine SystemSimilar in fxn to the Nervous System

    Both send a message- fxn of cell

    Nervous System-quick on, quick off

    Endocrine System-slow on, slow off 2012 Pearson Education, Inc.

    2012 Pearson Education, Inc.

    Figure 18-1 Organs and Tissues of the Endocrine SystemHypothalamusProduction of ADH, oxytocin, andregulatory hormonesPituitary GlandAnterior lobe:ACTH, TSH, GH, PRL, FSH, LH,and MSHPosterior lobe:Release of oxytocin and ADHParathyroid Glands(located on the posterior surface ofthe thyroid gland)Parathyroid hormone (PTH)Pineal GlandMelatonin597

    2012 Pearson Education, Inc.

    Figure 18-1 Organs and Tissues of the Endocrine SystemThyroid GlandThyroxine (T4)Triiodothyronine (T3)Calcitonin (CT)Adrenal GlandsAdrenal medulla:Epinephrine (E)Norepinephrine (NE)Adrenal cortex:Cortisol, corticosterone,aldosterone, androgensInsulinGlucagonPancreas (Pancreatic Islets)TestisOvaryThymus: (Undergoes atrophyduring adulthood)Secretes thymosinsAdipose Tissue: Secretes LeptinDigestive Tract: Secretesnumerous hormones involved in thecoordination of system functions,glucose metabolism, and appetiteKidneys: Secrete Erythropoietin (EPO) CalcitriolGonads:Testes (male):Androgens (especially testosterone),inhibinOvaries (female):Estrogens, progestins, inhibinOrgans with SecondaryEndocrine FunctionsHeart: Secretes natriuretic peptides. Atrial natriuretic peptide (ANP) Brain natriuretic peptide (BNP)SeeChapter21SeeChapter22SeeChapter25SeeChapters19 and 26SeeChapters28 and 29597

  • Hormone: organic chemical that changes the function of its target cellAutocrine-Paracrine-Endocrine-exocrine

    Copyright 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

    2012 Pearson Education, Inc.595

    Copyright 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

  • Maintenance of HomeostasisWater/electrolytesEnzyme functionTransport

    Regulate long term processesDevelopmentGrowthReproduction

    2012 Pearson Education, Inc.

  • Circulate freely-dont last longBind to receptorb.d. by liver or kidneysb.d. by enzymes in plasma or interstitial fluidBound to a carrier-last a long timeReserves in the blood streamOnce released from carrier-dont last longSame reasons as above 2012 Pearson Education, Inc.

  • Hormones

    Copyright 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

    598 2012 Pearson Education, Inc.

    Copyright 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

  • Copyright 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

    2012 Pearson Education, Inc.601

    Copyright 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

  • Copyright 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

    2012 Pearson Education, Inc.601

    Copyright 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

  • Copyright 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

    600

    Copyright 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

  • Copyright 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

    Mechanisms of Hormone ActionThe Process of Amplification Is the binding of a small number of hormone molecules to membrane receptorsLeads to thousands of second messengers in cellMagnifies effect of hormone on target cell 2012 Pearson Education, Inc.

    Copyright 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

  • Copyright 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

    Mechanisms of Hormone ActionDown-regulation Presence of a hormone triggers decrease in number of hormone receptorsWhen levels of particular hormone are high, cells become less sensitiveUp-regulationAbsence of a hormone triggers increase in number of hormone receptorsWhen levels of particular hormone are low, cells become more sensitive 2012 Pearson Education, Inc.

    Copyright 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

    2012 Pearson Education, Inc.

    Figure 18-3 G Proteins and Hormone ActivityHormoneProteinreceptorG proteinactivatedHormoneProteinreceptorG proteinactivatedEffects on cAMP LevelsMany G proteins, once activated, exert their effects by changing the concentrationof cyclic-AMP, which acts as the second messenger within the cell.Increasedproductionof cAMPadenylatecyclaseActs assecondmessengerkinaseActivatesenzymesOpens ionchannelsIf levels of cAMP increase,enzymes may be activatedor ion channels may beopened, accelerating themetabolic activity of the cell.Examples: Epinephrine and norepinephrine ( receptors) Calcitonin Parathyroid hormone ADh, ACTH, FSH, LH, TSH GlucagonExamples: Epinephrine and norepineph- rine (2 receptors)In some instances, G proteinactivation results in decreasedlevels of cAMP in thecytoplasm. This decrease hasan inhibitory effect on the cell.Enhancedbreakdownof cAMPPDEReducedenzymeactivityHormoneProteinreceptorG protein(inactive)G proteinactivated600

  • Copyright 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

    2012 Pearson Education, Inc.600

    Copyright 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

    2012 Pearson Education, Inc.

    Figure 18-3 G Proteins and Hormone ActivityHormoneProteinreceptorG protein(inactive)G proteinactivatedHormoneProteinreceptorG proteinactivatedEffects on Ca2+ LevelsSome G proteins use Ca2+ as asecond messenger.Examples: Epinephrine and norepinephrine (1 receptors) Oxytocin Regulatory hormones of hypothalamus Several eicosanoidsActivatesenzymesCalmodulinPLC,DAG,and IP3Opening of Ca2+ channelsRelease ofstored Ca2+from ER or SERCa2+ acts assecond messenger600

  • Copyright 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

    2012 Pearson Education, Inc.600

    Copyright 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

  • Copyright 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

    Endocrine Reflexes Endocrine Reflexes Functional counterparts of neural reflexesIn most cases, controlled by negative feedback mechanismsStimulus triggers production of hormone whose effects reduce intensity of the stimulus 2012 Pearson Education, Inc.

    Copyright 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

  • Copyright 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

    Endocrine Reflexes Endocrine reflexes can be triggered byHumoral stimuli Changes in composition of extracellular fluidHormonal stimuli Arrival or removal of specific hormoneNeural stimuli Arrival of neurotransmitters at neuroglandular junctions 2012 Pearson Education, Inc.

    Copyright 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

  • Copyright 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

    Endocrine ReflexesSimple Endocrine Reflex Involves only one hormoneControls hormone secretion by the heart, pancreas, parathyroid gland, and digestive tractComplex Endocrine ReflexInvolvesOne or more intermediary stepsTwo or more hormonesThe hypothalamus 2012 Pearson Education, Inc.

    Copyright 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

    2012 Pearson Education, Inc.

    Figure 18-5 Three Mechanisms of Hypothalamic Control over Endocrine FunctionProduction of ADHand oxytocinHYPOTHALAMUSControl of sympatheticoutput to adrenalmedullaeSecretion of regulatoryhormones to control activityof the anterior lobe of thepituitary gland

    Preganglionicmotor fibersAdrenal glandSecretion of epinephrineand norepinephrineAdrenal medullaAdrenal cortexPosterior lobeof pituitary glandRelease of ADHand oxytocinHormones secreted by the anteriorlobe control other endocrine organsAnterior lobeof pituitary glandInfundibulum602

  • Copyright 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

    Endocrine ReflexesNeuroendocrine Reflexes Pathways include both neural and endocrine componentsComplex CommandsIssued by changingAmount of hormone secretedPattern of hormone release:hypothalamic and pituitary hormones released in sudden burstsfrequency changes response of target cells

    2012 Pearson Education, Inc.

    Copyright 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

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