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 Form 3 Biology questions and answers on reproduction in animals

Describe the role of hormones in the human menstrual cycle

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Answer Text:
• It is controlled by sex hormones which are responsible for the onset of secondary sexual characteristics and also control of the menstrual
cycle
• The onset is signaled by discharge of blood/menses 14 days following the start of menstruation
• Anterior lobe of pituitary gland secretes follicle stimulating hormone(FSH)
• Follicle stimulating hormone causes graafian follicle to develop in the ovary. It also stimulates tissues of the ovary/wall (theca) to secrete oestrogen
• Oestrogen causes repair/healing of uterine wall
• Oestrogen stimulates anterior lobe of pituitary to produce luteinising hormonge (LH)
• LH causes ovulation. It also causes graafian follicle to change into corpus luteum. LH stimulates corpus luteum to secrete progesterone
• Progesterone causes proliferation/thickening of uterine wall
• Oesterogen/progesterone inhibits the production of FSH by anterior lobe of pituitary, thus no more follicles develop and oestrogen production reduces
• In the next two weeks progesterone level rises and inhibits production of LH from anterior lobe of pituitary
• The corpus lutetium stops secreting progesterone and menstruation occurs when the level of progesterone drops
• Anterior lobe of pituitary starts secreting FSH again.


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