Endocrine System I: Superior Glands  Homeostatic Mechanisms  Endocrine System vs Nervous System  Endocrine vs Exocrine Glands  Types and Actions of.

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<ul><li><p>Endocrine System I: Superior GlandsHomeostatic MechanismsEndocrine System vs Nervous SystemEndocrine vs Exocrine GlandsTypes and Actions of HormonesInteraction of Hormones with Target Cells Effects of Hormones on TargetControl Mechanisms of Endocrine GlandsEndocrine Signaling as Simple/Complex ReflexesMajor Superior Endocrine OrgansPituitary Anterior: GH, Pl, FSH, LH, TSH, ACTHPosterior: Oxytocin, ADHThyroid: TH synthesis and release; CalcitoninParathyroids: PTH</p></li><li><p>HomeostasisMaintenance of a stable internal environment = a dynamic state of equilibrium</p></li><li><p>Feedback MechanismsExample of Negative feedbackReceptor andLow blood glucose</p></li><li><p>Feedback MechanismsExamples of Positive feedback</p></li><li><p>Endocrine System I: Superior GlandsHomeostatic MechanismsEndocrine System vs Nervous SystemEndocrine vs Exocrine GlandsTypes and Actions of HormonesInteraction of Hormones with Target Cells Effects of Hormones on TargetControl Mechanisms of Endocrine GlandsEndocrine Signaling as Simple/Complex ReflexesMajor Superior Endocrine OrgansPituitary Anterior: GH, Pl, FSH, LH, TSH, ACTHPosterior: Oxytocin, ADHThyroid: TH synthesis and release; CalcitoninParathyroids: PTH</p></li><li><p>The Endocrine SystemA more broad-based and long-lasting communication system than the nervous systemUses chemical messages (hormones) that are released into the bloodHormones control several major processesReproductionGrowth and developmentMobilization of body defensesMaintenance of much of homeostasisRegulation of metabolism</p></li><li><p>Comparing Two Control SystemsNeuron wiring leading directly to and from targetHormones travel through blood stream systemicallyRapid, in millisecondsShort duration; response stops in seconds or minutesLong-lasting; minutes to daysNarrow &amp; specific, a few cells to part of one organBroad &amp; general; many target tissues and organs stimulated collectivelySlow; minutes, hours, or days</p><p>SystemMode of MessagingSpeed of SignalingLength of Response TimeRange of FocusNervous SystemEndocrine System</p></li><li><p>Endocrine System I: Superior GlandsHomeostatic MechanismsEndocrine System vs Nervous SystemEndocrine vs Exocrine GlandsTypes and Actions of HormonesInteraction of Hormones with Target Cells Effects of Hormones on TargetControl Mechanisms of Endocrine GlandsEndocrine Signaling as Simple/Complex ReflexesMajor Superior Endocrine OrgansPituitary Anterior: GH, Pl, FSH, LH, TSH, ACTHPosterior: Oxytocin, ADHThyroid: TH synthesis and release; CalcitoninParathyroids: PTH</p></li><li><p>Glandular EpitheliumGland one or more cells that secretes a particular productTwo major gland typesEndocrine glandDuctlessSecretions are hormonesExocrine glandEmpty through ducts to the epithelial surfaceInclude sweat and oil glands</p></li><li><p>Types of HormonesPeptide-based hormones</p><p>Steroid hormones</p><p>Prostaglandins and catecholaminesInsulin Growth hormone </p></li><li><p>Hormones as Chemical MessengersEndocrine gland (source)</p><p>Target organs or glandsHormones move through the bloodstream to target organs</p></li><li><p>Endocrine System I: Superior GlandsHomeostatic MechanismsEndocrine System vs Nervous SystemEndocrine vs Exocrine GlandsTypes and Actions of HormonesInteraction of Hormones with Target Cells Effects of Hormones on TargetControl Mechanisms of Endocrine GlandsEndocrine Signaling as Simple/Complex ReflexesMajor Superior Endocrine OrgansPituitary Anterior: GH, Pl, FSH, LH, TSH, ACTHPosterior: Oxytocin, ADHThyroid: TH synthesis and release; CalcitoninParathyroids: PTH</p></li><li><p>Hormone Interaction with Target CellsHormones bind to receptors sticking out from the plasma membrane of target cells or within target cells growth factor insulin epinephrine HormonesExamples of receptors found in the plasma membrane of cellsReceptors</p></li><li><p>Two Mechanisms of Hormone ActionSteroid hormone action</p><p> Diffuses through the plasma membrane of target cells Enters the nucleus or binds to cytoplasmic receptor Binds to a specific protein within the nucleus if not already bound Binds to specific sites on the cells DNA Activates genes that result in synthesis of new proteinsNon-steroid hormone action </p><p>1. Hormone binds to a membrane receptor; does not enter cell2. Sets off a reaction where a G protein with bound GTP activates adenylate cyclase enzyme.3. Adenylate cyclase produces cyclic AMP (second messenger) by converting ATP --&gt; cAMP 5. cAMP, in turn, activates phosphorylating activation proteins (protein kinases) that trigger additional intracellular changes (enzyme activation, secretion, ion channel changes) to promote a specific response(A few peptide hormones activate Ca+2 release via second messengers in the PIP2 calcium signaling system).G proteinAdenylateCyclasecAMP</p></li><li><p>Endocrine System I: Superior GlandsHomeostatic MechanismsEndocrine System vs Nervous SystemEndocrine vs Exocrine GlandsTypes and Actions of HormonesInteraction of Hormones with Target Cells Effects of Hormones on TargetControl Mechanisms of Endocrine GlandsEndocrine Signaling as Simple/Complex ReflexesMajor Superior Endocrine OrgansPituitary Anterior: GH, Pl, FSH, LH, TSH, ACTHPosterior: Oxytocin, ADHThyroid: TH synthesis and release; CalcitoninParathyroids: PTH</p></li><li><p>Effects Caused by HormonesChanges in target cells by hormonal activationChanges in plasma membrane permeability or electrical stateSynthesis of proteins, such as enzymesActivation or inactivation of enzymesStimulation of mitosisActivation of transcription of certain genesTarget cell activation depends on three factorsBlood levels of the hormoneRelative number of receptors on or in the target cellAffinity of binding between receptor and hormone</p></li><li><p>Target Cell ActivationHormones influence the number of their receptorsUp-regulationtarget cells form more receptors in response to the hormoneDown-regulationtarget cells lose receptors in response to the hormoneHormones are removed from the blood byDegrading enzymesKidneysLiver Half-lifethe time required for a hormones blood level to decrease by half</p></li><li><p>Control of Hormone ReleaseHormone levels in the blood are maintained by negative feedbackA stimulus or low hormone levels in the blood triggers the release of more hormoneHormone release stops once an appropriate level in the blood is reached</p></li><li><p>Endocrine System I: Superior GlandsHomeostatic MechanismsEndocrine System vs Nervous SystemEndocrine vs Exocrine GlandsTypes and Actions of HormonesInteraction of Hormones with Target Cells Effects of Hormones on TargetControl Mechanisms of Endocrine GlandsEndocrine Signaling as Simple/Complex ReflexesMajor Superior Endocrine OrgansPituitary Anterior: GH, Pl, FSH, LH, TSH, ACTHPosterior: Oxytocin, ADHThyroid: TH synthesis and release; CalcitoninParathyroids: PTH</p></li><li><p>Control Mechanisms of Endocrine GlandsHormonal: Chemical stimulus (i.e. endocrine glands are activated by other hormones</p><p>Humoral: Changing blood levels of certain ions stimulate hormone release</p><p>Neural: Nerve impulses stimulate hormone release; most are under control of the sympathetic nervous system</p></li><li><p>Endocrine Signaling (Reflexes)Figure 9.3Simple Endocrine Reflex Involves only one hormone Controls hormone secretion by the heart, pancreas, parathyroid gland, and digestive tract</p><p>Complex Endocrine ReflexInvolves: One or more intermediary steps Two or more hormones (tropic hormones cause secretion of a second hormone in target glands) The hypothalamus</p></li><li><p>Location of Major Endrocrine OrgansFigure 9.3</p></li></ul>

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