MODULE 24Objectives:After completing this topic you should be able to: Explainthegenericroleofthe endocrine system Describetherelationshipbetweenthe pituitary and the hypothalamus Describethehormonalcontrolofblood glucose levelsIntroduction: There is a second system in the body that is responsible for relaying information and maintaining homeostasisthe endocrine system. While the nerve impulses are essentially immediate in their action hormones are usually slower in their initiation of response but also exhibit their effects for a longer period of time. Therefore we often find that the nervous system may exert short term control while long term control is mediated by hormones.FUNCTIONS !oordinatestogether with the nervoussystem the activities of the body "nvolved in the synthesis and secretion ofhormones #ormonal functions include:$control of energy production and utili%ation $control of the composition of extracellular water and electrolytes $maintains normal growth and developmentFiure 24!" M#jor endocrine $#nds in %unENDOCRINE 'L(NDS Ductless glands that synthesi%e and secretehormones. A hormone is an organic substance neededby the body in minute&uantities to elicit a specific physiologicalresponse. #ormones are produced by one part of the body thathave an effect on specifictarget cells located indifferent parts of the body.)*+ot%#$#&us A small gland about'.( cm in diameterlocated at the base of the brain "ntimately associatedwith the pituitary gland )ecretes releasinghormones that travelvia a portal system and stimulate the anteriorpituitary,ituit#r* '$#nd Asmallgland locatedatthebaseof thebraininthe depression of thes*ull !onnectedtothe brainthroughashort stal*called infundibulumDivisions o- t%e +ituit#r* $#nd Anterior lobe or adenohypophysis$)ecretes + hormones: $,)# follicle-stimulating hormone $.#luteini%inghormone/infemale0or"!)#interstitialcell-stimulatinghormone /in male0 $luteotrophic hormone or prolactin $A!T# adrenocorticotrophic or prolactin$T)# thyroid-stimulating hormone$)T# somatotrophic hormone or 1# growthhormone Posterior lobe or neurohypophysis$)ecretes 2 hormones: $3asopressin forconstriction of the vessels$AD# antidiuretic hormone$4xytocin controls smooth musclesDivisions o- t%e +ituit#r* $#ndT%*roid '$#nd !omposed of two lobes on each sideof the trachea connected by an isthmus )ecrete thyroxin that regulate growthand development Enlargement of this gland results in a condition *nown as goiter,#r#t%*roid '$#nd )mall glandular bodies located onthe dorsal surfaceof the thyroids )ecrete parathormones/5T#0 thatmaintains the ration of calciumand phosphorusin the bodyT%*&us '$#nd .ocated between the upper part of thesternum and thepericardium. A temporary organ which reaches greatest developmentat age '6 to '+. )ecretes thymosin that controlsmetabolic rate andinvolved in the formation of W7!.(dren#$ Corte. )ecretes cortisol and aldosterone thatcauses gluconeogenesis and sodiumretention and potassium excretion in the*idneys respectively(dren#$ Medu$$# Two small masses located above the *idneys )ecrete epinephrine and norepinephrine 5romotes 8flight or fight9 reactionsduring emergency,#ncre#s 7oth an exocrine and endocrine gland The endocrine part consists of the islets of .angerhans thatsecrete the hormoneinsulin "nsulin lowers theblood sugar littlesecretion resulted into diabetes mellitus'on#dsThe interstitial cells /.eydig cells0 of thetestes secretetestosterone The follicles of the ovary secretes estrogenthe corpus luteum secretes progesteroneT#b$e 24!" M#jor endocrine $#nds #nd t%eir %or&onesGlandHormonesMajorFunctionsDisorderfromtoomuchsecretionDisorderfromtoolittlesecretionHypothalamusReleasinghormonesStimulatesanteriorpituitaryOveractiveanteriorpituitaryUnderactiveanteriorpituitaryAnteriorpituitaryhyroid!stimulating"SH#StimulatesthyroidOveractivethyroidUnderactivethyroidAdreno!corticotropic"A$H#Stimulatesadrenalcorte%Overactiveadrenalcorte%Underactiveadrenalcorte%Follicle!stimulating"FSH#RegulateseggandspermproductionOveractiveovaries&testesUnderactiveovaries&testes'uteini(ing"'H#or)nterstitialcell!stimulating")$SH#Regulatesse%hormonesproductionOver!secretionofse%hormonesUnder!secretionofse%hormones*rolactin"*R'#$ausesmil+productionaftergiving,irthOver!secretionofmil+Under!secretionofmil+Gro-th"GH#*romotesgro-thGigantismD-arfismT#b$e 24!" M#jor endocrine $#nds #nd t%eir %or&ones cont!GlandHormonesMajorFunctionsDisorderfromtoomuchsecretionDisorderfromtoolittlesecretion*osteriorpituitaryAntidiuretic"ADH#$auses-aterretention,y+idneys"Diverse#Dia,etesinsipidusO%ytocin$ausesuterinecontraction *inealMelatonin)nhi,itsreleaseofgonadotropinSe%ualimmaturitySe%ualmaturityhymushymosinRegulatesdevelopmentandfunctionsofimmunesystemOveractiveimmunityUnderactiveimmunityhyroidhyro%in)ncreasesmeta,olicrateandcellularrespiration.%ophthalmicgoiterSimplegoiter/cretinism$alcitoninDecreasesplasmalevelofcalciumetany0ea+,ones*arathyroid*arathormone"*H#)ncreasesplasmalevelsofcalciumandphosphorus0ea+,onesetanyAdrenalcorte%$ortisol$ausesgluconeo!genesis Aldosterone$ausessodiumretentionandpotassiume%cretion,y+idneys$ushing1ssyndromeAddison1ssyndromeT#b$e 24!" M#jor endocrine $#nds #nd t%eir %or&ones cont!GlandHormonesMajorfunctionsDisorderfromtoomuchsecretionDisorderfromtoolittlesecretionAdrenalmedulla Epinephrine andnorepinephrinePromotesflight or fightreactions *ancreas Insulin Lower blood sugarShock Diabetesmellitus Glucagon aises blood sugarestes !ndrogen"#estosterone$ Promotessecondar%malecharacteristics Ovaries Estrogen andprogesterone Promotessecondar%femalecharacteristics Se$-/Test 24!0 Endocrine S*ste&A. Match the terms to the following definitionsB.Anterior pituitary E. PancreasC.Posterior pituitary F. AdrenalD.Thyroid . TestesE.Parathyroid !. "#ariesSe$-/Test 24!0 Endocrine S*ste&$$$$'.:aintains the supply of !a and 5 in the body.$$$$;..5romotes 8,light or fight9 reactions duringemergency.$$$$?.5romotes female secondary sexual characteristics.$$$$@.)ecrete testosterone.$$$$'(. )ecretes insulin that lowers blood sugar.Se$-/Test 24!0 Endocrine S*ste&B.Match the following ductless glands to the hormones they secreted. $$$$''.#ypothalamus A. :elatonin$$$$';.5ituitary 7. ,)# and .#$$$$'2.5ineal !. Testosterone$$$$'6.Thymus D. Thyroxin$$$$'=.Thyroid E. Epinephrine$$$$'+.5arathyroid ,. Estrogen$$$$'>. Adrenal1. 1n