Menstrual cycle

Menstrual cycle

1. Menstrual cycle

2. What is the menstrual cycle?
•Theprocessinwhichfemalesripenorreleaseonematureegg.
•Theaveragemenstrualcyclewillrepeatitselfaboutevery28days,butnormal
menstrualcyclescanrangefrom21to40days.
•Rhythmicalseriesofphysiologicalchangesthatoccurinfertilewomen
•Underthecontroloftheendocrinesystem
•Necessaryforreproduction
•Averagelength:28days,buttypicallyvaries,withshorterandlongercycles
•Menarche:awoman'sfirstmenstruation
–typicallyoccursaroundage12
–occurrencedependsonoverallhealthanddiet
•Menopause:endofawoman'sreproductivephase,commonlyoccursbetween
ages45and55

5. Phase
Average start
andend day
(assuming a 28-
day cycle)
Menstrual phase 1-4
Proliferative phase 5-13
Ovulation 13-16
Secretory phase 16-28

8. FOLLICULAR PHASE
Duetotheriseoffolliclestimulatinghormone(FSH)duringthefirst
daysofthecycle,severalovarianfolliclesarestimulated
Folliclescompetewitheachotherfordominance
ThefolliclethatreachesmaturityiscalledaGraafianfollicle
Astheymature,thefolliclessecreteincreasingamountsofestrogen,
whichthickensthenewfunctionallayerofendometriumintheuterus
Estrogenalsostimulatescryptsinthecervixtoproducefertilecervical
mucus
Attheendofthisphaseovulationoccurs

10. OVULATION
•Duringthefollicularphase,estrogensuppressesproductionofluteinizing
hormone(LH)fromthepituitarygland
•Whentheovumhasnearlymatured,levelsofestrogenreachathresholdabove
whichtheystimulateproductionofLH(positivefeedbackloop)
•ThereleaseofLHmaturestheovumandweakensthewallofthefollicleinthe
ovary,causingthefullydevelopedfollicletoreleaseitssecondaryoocyte
•Afterbeingreleasedfromtheovary,theovumissweptintothefallopiantube

12. LUTEAL PHASE
•Corpusluteum:solidbodyformedinanovaryaftertheovumhasbeen
releasedintothefallopiantube
•Producessignificantamountsofprogesterone,whichplaysavitalrolein
makingtheendometriumreceptivetoimplantationoftheblastocyst
•HighlevelsofEandPsuppressproductionofFSHandLHthatthecorpus
luteumneedstomaintainitself
•Fallinglevelsofprogesteronetriggermenstruationandthebeginningofthe
nextcycle

14. MENSTRUALPHASE
Menstruation
menstrualbleeding,menses,period
dischargeofbloodyfluidcontainingendometrialcells,glandular
secretionsandbloodcells,lasts3-5days
resultofthepreviousmenstrualcycle
duetostrongvasoconstrictionandproteolyticactivity,functional
stratumofendometrialtissuediesandisdischargedduringmenstrual
bleeding
Endometriumbecomesverythin,butduetolowestrogenlevels,
hypophysissecretesmoreFSH
FSHstimulatessecretionofestrogen,andestrogenservesasproliferation
signaltotheendometrialbasallayer