a) State any two functions of the placenta. (2mks) Describe the role of hormones in the human menstrual cycle. (18mks)

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a) Two functions of the placenta
- serves for the exchange of materials between the mother and the foetus.
- Serves as endocrine organ- forms source of progesterone  hormone which is  important in female reproduction.

b) The role of hormones in the human menstrual cycle
the menstrual cycle begins on the very first day of the menstrual flow.
pituitary gland starts to secrete follicle stimulating hormone (FSH)
The FSH causes development of a Graafian follicle in the ovary. It also stimulates the walls of the follicle/tissues of the ovary to start secreting oestrogen.
Oestrogen causes repair and healing of the uterine wall.  It also stimulates the pituitary gland to secrete the lutenising hormone (LH)
 LH stimulates the final maturation of the Graafian follicle and ovulation.
Following ovulation, LH causes remains of the Graafina follicle to re-organize into a corpus luteum.
LH stimulates the corpus luteum to secrete the hormone progesterone.
Progesterone causes the lining of the uterus to get thickened, folded and invaded by blood vessels in readiness for implantation.
Progesterone and oestrogen also inhibit production of FSH which in turn prevents the development of another follicle and oestrogen production falls.
In the next two weeks after ovulation, progesterone level rises and inhibits production of LH from the pituitary gland.  The corpus luteum stops secretion of progesterone.  The sudden drop in the level  of progesterone causes menstruation to occur and the pituitary gland starts secreting FSH again.min;9 points;2 marks each.

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