Pituitary gland and it's hormones.

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Assignment of
physiology
Pituitary gland hormones inphysiological
coordination
Thistopic containsthe informationaboutthe pituitarygland
and the hormoneswhichare secretedbydifferentlobesof
pituitaryglandandtheirrolesinthe physiological
coordination.
MALAIKA MUSKANRoll No.875
SEMESTER.5 submitted to:Dr. SAGEER
AHMED
11/14/2019

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PITUITARY GLAND:
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 The pituitaryglandisthe pea-sizedglandthatishousedwithinabonystructure (sellaturcica) at
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the base of brain.The sellaturcicaprotectsthe pituitarybutallowsveryroomforexpansion.
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 The pituitary glandcontrols the functionof mostotherendocrine glandandistherefore
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sometimescalledmastergland.
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 In turn,the pituitaryiscontrolledinlarge partby the hypothalamus,aregionof brainthatlies
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justabove the pituitary.
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The pituitaryhastwo distinctparts:
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 Anteriorlobe
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 Posteriorlobe
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 The lobesare connectedtothe hypothalamusbyastalkthat containsbloodvessels andnerve
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cell projections(nerve fibers,oraxon).
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 The hypothalamuscontrolsthe anteriorlobe byreleasinghormonesthroughthe connecting
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bloodvessels.itcontrol the posteriorlobe throughnerveimpulse.
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PITUITARY AND THE TARGET TISSUES:
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 The pituitary gland produces a different hormones affects a specific part of
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body i-e, target organ or tissues.
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HORMONES TARGET ORGANS/
TISSUES
ADENOCORTICOTROPICHORMONE(ACTH) ADRENALGLAND
MSH SKIN
FOLLICLE STIMULATING HORMONES (FSH) OVARIESORTESTES
GROWTH HORMONES MUSCLE ANDBONE
LUTEINIZINGHORMONES (LH) OVARIESORTESTES
OXYTOCIN UTERUS ANDMEMORY GLAND
PROLACTIN MAMMARY GLAND
THYROID STIMULATING HORMONES THYROID GLAND
VASOPRESSIN KIDNEYS
ENDORPHIN BRAIN ANDIMMUNE SYSTEM
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LOBES OF PITUITARYGLAND:
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 ANTERIORLOBE
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 POSTERORLOBE
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 Medianpituitary
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 Each lobe produces andrelease differenthormones.
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 Detail below:
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Anterior lobe hormones:
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 The anterior lobe produces and release six main hormones:
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1) STH (SOMATOTROPIN)
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2) FSH ( FOLLICLE-STIMULATING HORMONE)
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3) TSH (THYROID STIMULATING HORMONE)
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4) ACTH ( ADRENOCORTICOTROPIC HORMONE)
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5) PROLACTIN
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6) LUTEINIZING HORMONE
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Hormones and their function:
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All theHORMONESof majorpituitary,exceptforgrowth hormones,exerttheir principal effects mainly
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by stimulating targetglands,including thyroid gland,adrenalcortex,ovaries,testicles,and mammary
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gland.The function of each of these pituitary hormonesareso intimately concerned with the function of
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respective targetgland that,exceptforgrowth hormones,theirfunction aredescribed below;
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1) Growthhormone:(SOMATOTROPIC)
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Growth hormonesalsocalledsomatotropinorsomatotropichormone,isasmall proteinmolecule that
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contains191 aminoacids ina single chainandhas a molecularweightof 22,005.
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FUNCTION:
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1. Growth hormoneswhichregulates the growthof bonesandmuscles.
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2. It alsoregulatesthe physical development andhasimportanteffectsonbodyshape by
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stimulatingmuscle.
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3. It has multiple specificmetaboliceffectslike;enhancesbodyprotein,decrease fat store
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and conserve carbohydrates.
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4. Promote the proteindepositionintissues
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5. It directlyenhancesthe transportof aminoacidsthroughthe cell membrane to interior
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of cell.
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6. Increasednucleartranscriptionof DNA toformRNA
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7. It alsodecrease the catabolismof proteinandaminoacids.The probable reasonforthis
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decrease isthatGH alsomobilize the large quantitiesof free fattyacidsfromthe
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adipose tissuesandthese are usedtosupplymostof the energyforthe bodycells thus
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actingas a “proteinsparer”.
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2) TSH:(Thyroidstimulating hormones)
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Thyroid-stimulatinghormone,whichstimulates thethyroidglandto producesthyroidhormones.
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Thyroidhormones are as follow;
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1) Thyroxin
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2) Triiodothyronine
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FUNCTION:
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1) Increase the transcriptionof large numbersof genes.
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2) Thyroidhormonesactivate the nuclearreceptors.
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3) Increase the cellularmetabolicactivity;increase the numberandactivityof
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mitochondria,increasethe Active transportof ionsthroughcell membrane.
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4) These hormonesalsohave effectongrowth.
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5) Effecton specificbody functionlike;stimulationof fatsandcarbohydrates
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metabolism;increase the heartrate ,heartstrength ,respiration,gastrointestinal
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motility,bloodflow &cardiacoutputetc.
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6) Effecton sexual functions.
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Thyroidand its working:
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3) ACTH: (adrenocorticotropic hormone)
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Adrenocorticotropichormonealso called corticotrophin,which stimulatethe adrenalgland to produce
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cortisol, corticosterone,aldosterone and otherhormones.
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 Adrenal glandhastwosections;cortex andmedulla.
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 Both sectionssecrete differenthormonesandperformdifferentfunctions:
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The hormones of adrenal cortex are:
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 Mineralocorticoid
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 Glucocorticoid
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 Testosterones
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The hormones of adrenal medullaare:
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 Epinephrine
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 Nor-epinephrine
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Functions:
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1) Aldosteroneincreases renal tubularreabsorptionof sodiumandsecretionof potassium.
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2) Aldosteronestimulatessodiumandpotassiumtransportinsweatglands,salivaryglands
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and intestinal epithelialcellstoconserve bodysaltinhotenvironmentandthe effecton
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salivaryglandisnecessarytoconserve saltwhenexcessive salivaislost.
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3) Metaboliceffectof Cortisol andglucocorticoidonmetabolismisthe ability tostimulate
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gluconeogenesisbyliver.
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4) Cortisol increasesthe enzymesrequiredtoconvertaminoacidstoglucose inlivercells.
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5) Effectsof cortisol onproteinmetabolism;reductioninthe cellularprotein.
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6) Effecton cortisol on fat metabolism;metabolizationof fattyacids.
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7) Epinephrineeliminatesthe productionof gastrin.
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8) It facilitatesthe bloodmovetowardsthe muscles.
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9) Nor-epinephrineresiststhe bloodtomove towardsstomach.
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ACTH and it’s working.
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4) PROLACTIN:
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It producesfromadenohypophysisby nature.Itispolypeptidechain.The targetcells are gonads.
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Function.
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1. Premigrationrestlessnessinbirds
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2. Courtshipdances
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3. Courtshipsounds
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4. Changesinexternal genitalia
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i)Size of labiamajora&minors(females)
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ii) Size of penis
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iii) Colorchanges
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5. Onsetof rut signs
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6. Initiate andmaintainlactation
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7. Induce ductal growthof breast
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8. Induce lobular-alveolarsystem
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9. It takespart insynthesisof milkproteinlike caseinandlactoalbumin
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10. It isimportantincontrol of osmolality
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11. It helpsfetal lungdevelopment
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12. Take part informationsteroidsfromadrenal cortex,testesandovaries
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5) FSH: {Follicles-stimulating hormones}
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FSH is a gonadotropin,a glycoprotein polypeptidehormone.FSHis synthesized and secreted by the
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gonadotropic cells of theanterior pituitary gland.
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Function:
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1) In women,thishormone stimulatesthe growthof ovarian folliclesinthe ovarybefore the
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release of aneggfrom one follicleatovulation.
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2) In men, itstimulates testiculargrowthandenhancesthe productionof anandrogen-binding
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proteinbythe sertoli cells,whichare a componentof the testiculartubule necessaryfor
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sustainingthe maturingspermcells.
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3) Pubertal development
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6) Luteinizing hormone:
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LH is a hormoneproduced by gonadotropiccells in the anteriorpituitary gland.
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Function:
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1. In females,anacute rise of LH triggersovulationanddevelopmentof the corpusluteum.
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2. Promote the secretionof estrogenfromthe mature follicle
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3. Release the ovum fromthe ovarianfollicles
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4. Corpusluteumproducesprogesterone andestradiol underthe influence of LH.
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5. Produce the testosterone fromthe leydigcellsoff testes.
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Posterior lobe hormones:
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 The hormonesof posteriorlobe of pituitary gland are:
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 Oxytocin
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 Vasopressin
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1) Vasopressin:
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Vasopressiniscalledsobecause of constrictionof bloodvessels.Thisisalsoknownasanti-diuretic
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hormone.
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Function:
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The functionof vasopressinis:
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1. Regulate the tonicityof body
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2. Reabsorbthe solute-free waterandreturnitto the circulationfromtubulesof nephron
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3. Maintainosmolality(concentrationof dissolvedsubstancessuchasglucose,inthe serum)
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4. Maintainthe volume of waterinextracellularfluid
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5. Increase bloodvolume,cardiacoutputandarterial pressure
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6. Anotherfunctionisvasoconstriction
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7. It isusedto manage the anti-diuretichormone deficiency
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2) Oxytocin:
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Oxytocinisalsoknownaslove hormone,isreleasedbypituitarygland andisresponsibleforhuman
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behaviorassociatedwithrelationshipandbonding.
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Function:
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1. It ismostlyusedto helpmotherproduce the contractionsinlaborandcontrol bleeding
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2. It stimulatesthe uterine musclestocontractand alsoincrease the productionof prostaglandins,
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whichincrease the contractionfurther
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3. Stimulatesthe milkejection
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4. It isfoundinmentoo and has effectontestosteroneproductionandmovementof sperm
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5. It isalso involvedinsexual arousal andlove bonding
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Median pituitary lobe:
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Medianpituitarylobe secretesthe MSH(melanocytes-stimulatinghormone).
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Function:
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MSH stimulatesthe productionandrelease of melanin( aprocessreferredtoasmelanogenesis) by
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melanocytesinskinandhairs.Actinginhypothalamus,MSHsuppressesthe appetite.Thisalso
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contributesinsexual arousal.
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Exercise:
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Mcq’s
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1) The target organ/organsof Oxytocinis/are:
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a) Uterus b) mammary glands c) testes d) a&b both
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2) The anteriorlobe of pituitaryglandcomprisesthe _______ weightof whole pituitarygland:
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a) 60% b) 70 % c) 80% d) 90%
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3) Somatotropichormonesconsistsof ____ aminoacids
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a) 121 b) 181 c) 191 d) none of these
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4) Whichhormone isalsoknownas love hormone?
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a) Vasopressin b) Oxytocin c) FSH d) b&c both
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5) Whichhormone helpsinthe productionof milk?
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a) Oxytocin b) prolactin c) epinephrine d) vasopressin
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Short questions:
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1. Write any three hormonesof anteriorlobe of pituitaryandtheirtargetorgans. (page no2)
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2. What isthe role of FSH inthe men? ( line no171 page no 10)
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3. Why vasopressiniscalledso? (line no195 page no 11)
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4. Write any 3 functionsof LH (line 184__187 page no 10)
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5. What are the functionsof epinephrine andnor-epinephrine? (line no131 & 133 page no 7)
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Extensive question:
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1) Write any 3 hormonesof pituitaryglandwiththeirphysiological roles.
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