walt ; describe how the menstrual cycle works
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WALT ; Describe how the menstrual cycle works . All can identify the 4 hormones involved. Most can describe how they regulate the menstrual cycle Some can explain how the negative feedback mechanism controls the menstrual cycle. The menstrual cycle? . Fertility. - PowerPoint PPT PresentationTRANSCRIPT
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WALT ; Describe how the menstrual cycle works
All can identify the 4 hormones involved.
Most can describe how they regulate the menstrual cycle
Some can explain how the negative feedback mechanism controls the menstrual cycle
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The menstrual cycle?
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Fertility3 hormones are involved in the menstrual cycle: oestrogen, LH and FSH. Here’s how:
Step 3: LH stimulates the release of the mature egg in the middle of the menstrual cycle
Artificial fertility:1) To INCREASE fertility FSH is given to stimulate maturation of
eggs.2) To DECREASE fertility oestrogen is given (“The Pill”) to inhibit
FSH production stopping eggs from maturing.
Step 1: FSH produced by the pituitary gland causes both an egg to mature and the ovaries to start producing oestrogen
Step 2: The rising levels of oestrogen cause the pituitary gland to stop producing FSH and produce LH instead
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Inside the ovaryWhat happens in the ovary during the menstrual cycle?
Day 1-13:egg developing inside the growing follicle
Day 14:ovulation – egg released from follicle
Day 15-28:empty follicle turns into corpus luteum (yellow body)
immature eggs
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Uterus liningThe lining of the uterus becomes thicker with blood vessels and more stable during the menstrual cycle. Why is this important?
2 106 84 12 14 16 18 20 22 24 26 28days after start of period
uter
us li
ning
thic
knes
s
period
A fertilized egg will bury itself (implant) in the uterus lining. The egg needs a plentiful supply of oxygen and nutrients to develop.
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Hormone levels
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PregnancyIf the egg is fertilized, the uterus lining must not break down otherwise the fertilized egg will not develop.
corpus luteum: continues to produceprogesterone and oestrogen
egg fertilized:uterus lining maintained, egg implanted
progesterone memoTo: uterusFrom: corpus luteumMaintain uterus lining.
oestrogen memoTo: pituitaryFrom: corpus luteum
Don’t send FSH.
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How does the contraceptive pill work?
progesterone memoTo: pituitaryFrom: contraceptive pill
Stop sending FSH.
Contraceptive pills contain progesterone and need to be taken every day. How do they work?
no FSH received:no egg maturing
Contraceptive pills mimic pregnancy, which means that the ovaries do not produce any eggs.
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Summary of fertility hormones