The Human Menstrual Cycle w w Consists of
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The Human Menstrual Cycle! w w Consists of 3 distinct phases The cycle is typically 28 days It is not always 28 days for all women all the time For example Athletics/stress/malnutrition may cause a cycle to STOP w Or some women may based on stress/age/ health have longer or shorter cycles
I – Menstrual Phase: w Occurs between Day 28/1 to Day 3 -4 w Most hormones are low (FSH, LH, Progesterone & Estrogen), but Oxytocin is HIGH. w The endometrium lining breaks down to be SHED w 1 st day of bleeding is the 1 st day of the NEW CYCLE w 2 -8 day loss period, where 20 -80 ml of blood is SHED
II – Follicular Phase: w w Named for the developing FOLLICLE (Day 4 -14) Release of FSH & LH increases The ovary is stimulated to release ESTROGEN ENDOMETRIUM thickens to support the IMPLANTATION of the ZYGOTE! w Ovulation occurs at the peak of FSH & LH release (Day 14) w Body temperature increases at the time of ovulation w Fertility remains high for 3 -5 days!
III – Luteal Phase: w Named for the CORPUS LUTEUM (forms after Ovulation) (Day 14 -25) w The envelop of the Follicle becomes the CORPUS LUTEUM w Corpus Luteum produces PROGESTERONE a) maintains the endometrium b) –ve feedback to APG to stop FSH release Why is this important?
III – Luteal Phase… w Corpus Luteum maintains progesterone throughout pregnancy or until Day 25 if no fertilization has occurred! w PLACENTA eventually takes over PROGESTERONE production to maintain the PREGNANCY! see green line above, it may continue for 9 months!
A simple view of Pro & Estro & Endometrium
See your handout & write Note the peaks of each hormone & when they occur!
How Menstrual Feedback works! *** write on your handout*** w Hypothalamus contains the chemoreceptors that respond to increasing Progesterone & Estrogen levels (Pro & Estro) w As Pro & Estro increase the hypothalamus stops release of Gn. RH (Gonadotropin Releasing Hormone Puberty initiator) w As Gn. RH decreases the APG ceases FSH & LH release RU Ready!
How Menstrual Feedback works… w After Day 14 no more eggs will be stimulated to grow! WHY? w This is the basis of the PILL mimic an existing –ve feedback system by introducing Pro & Estro during the Follicular Phase! w Pill is also medicinal regulate cycles, treats menstrual disorders (like endometriosis) etc w Our Catholic Faith calls for us to examine our reasons for this artificial treatment to the body & the decisions we make! w It is not meant to cheat our biological nature & abdicate our responsibilities for the creation of life!
See your handout & write w Note the targets of estrogen & progesterone! w Also note the event before & after ovulation!
What Now! w Menstrual Cycle Review Worksheet 1, 4, & 5 w STS assignments on CLONING st n Dolly the 1 mammal clone A sheep n Now Pigs for various reasons n What next Humans for various reasons!
