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This cheatsheet is about GCSE Biology - Menstrual Cycle
This is a draft cheat sheet. It is a work in progress and is not finished yet.
Hormones
Hormone |
Produced in... |
Causes... |
Follicle stimulating hormone |
Pituitary gland |
Egg ripening and oestrogen production |
Oestrogen |
Ovaries |
Lining of the room to develop |
Luteinising hormone |
Pituitary gland |
Egg release and progesterone production |
Progesterone |
Ovaries |
Lining of womb maintenance |
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Stages
Menstruation – loss of lining from the uterus, occurs at the start of the cycle if no fertilisation has occurred |
The lining starts to thicken |
Ovulation occurs around the middle of the cycle (about day 14), the egg travels down the oviduct towards the uterus |
The lining is maintained ready to accept a fertilized egg |
Graph
Women over 50 are less likely to ovulate because they don't have high levels of oestrogen and high levels of oestrogen are needed for LH to build up.
Women are less likely to menstruate after the age of 60 because they too have low levels of oestrogen, so a uterus lining will not be built up so no lining will need to be lost.
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How hormones control the menstrual cycle
At the start of the cycle, FSH causes the egg to develop in the follicle. |
FSH is released from the pituitary gland. |
As progesterone and oestrogen levels are low, oestrogen starts to rise, causing the lining of the uterus to build up |
The high levels of oestrogen cause a surge of LH |
Progesterone is produced from the corpus luteum, causing thelining of the uterus to be maintained. |
If an egg is fertilised,oestrogen and progesterone levels remain high to maintain the lining of the uterus |
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