EndocrineSystemPt.2Lesson7

LearningGoals

1. Becomefamiliarwiththethyroid,parathyroid,adrenal,andpinealgland

2. Whatarethedifferenttypesofhormonesproduced/releasedinthesefourglands?

2majorendocrineglands?

4typesofhormoneswehaveseensofar?

Sofar…

AnteriorPituitary

1. GrowthHormone(GH)

2. Prolactin(PRL)

PosteriorPituitary

1. AntidiureticHormone(ADH)

2. Oxytocin(OT)

Fourglands

1. Thyroid2. Parathyroid3. Adrenal4. Pineal

ThyroidGland

• Frontofthethroat

• Stimulatedbythyroidstimulatinghormone(TSH)fromanteriorpituitary•Whichisactivatedbythethyroidreleasinghormonefromthehypothalamus

T4andT3

•SecretesThyroxine(T4)andtriiodothyronine(T3)• Regulatesbodymetabolismandthegrowthanddifferentiationofdifferenttissues

•NegativeFeedback

Iodine

• Iodine(I)isnecessarytoproducethyroidhormones(T4)• Ifnoiodine,thennoT4isproduced• PituitaryglandwillcontinuetoreleaseTSHwhichcausesthethyroidtoswell➡ goiter

Calcitonin

•Lowerscalciumionconcentrationinblood

•Ifbloodcalciumlevelsarehigh:• Calcitoninisreleasedfromthethyroidgland

•Calcitonincauses• DecreasereabsorptionofCa2+indistaltubuleofkidneys• Ca2+tobedepositedinthebones

ParathyroidGland

• Locatednearthyroidgland

•Produceparathyroidhormone(PTH)• Actstoincreasebloodcalciumlevels• StimulusislowCa2+levelintheblood

Parathyroidhormone

•IncreasesCa2+ionconcentrationsinblood

•Ifbloodcalciumlevelsarelow:• PTHisreleasedfromparathyroidgland

•PTHcauses• ReabsorptionofCa2+kidneys• Ca2+releasefrombones

Parathyroidhormone

•NotenoughPTHresultsin:• DecreaseCa2+concentrationinblood=muscletwitchesanduncontrollablecontractions

• ToomuchPTHresultsin:• LossofCa2+frombones=osteoporosis• IncreaseCa2+concentrationinblood=kidneystones

RegulationofCalcium

AdrenalGland

• Locatednearthekidney:2regions

1. Adrenalmedulla2. Adrenalcortex

AdrenalMedulla

• Controlledbynervoussystem(“fightorflight”)tohelpbodyrespondtostress• Secretesepinephrineandnorepinephrine• ⬆ overallcellmetabolism• ⬆ heartrate• ⬆ breakdownofglycogenandfatstoincreasebloodglucose

• Dilatebloodvesselstoheart,lungs,muscles(moreoxygenandnutrienttoreachtissues)

AdrenalCortex

• Cortisol• Worksinthelivertohelpregulatebloodglucoselevels• Promotesbreakdownoffatswhenbloodglucoselevelislow

• Aldosterone• Helpscontrolbloodpressureandosmoregulation• IncreasesNa+reabsorption(andwaterreabsorption)inthekidney

PinealGland

• Secretesmelatonin• Maintainsdailybiorhythms(biologicalclock)• Decreasemotoractivity,inducesfatigue,lowersbodytemperature• Regulatedbyinhibitorypathway,whenlighthitstheeyesà Secretionmostactiveduringperiodsofdarkness• Targetsthehypothalamus

Homework

•HandoutQuestions