MENSTRUAL CYCLE ESSAY | Life Science Grade 12

MENSTRUAL CYCLE ESSAY

Is the series of events that occur in a female body for 28 days to pre pare for possible pregnancy?
It occurs in two cycles namely the ovarian cycle and uterine cycle
❖ The pituitary gland secretes FSH
❖ Which stimulates the development of primary follicle into Graafian follicle
❖ Graafian follicle secretes Oestrogen
❖ Which stimulates the thickening if endometrium in preparation for pregnancy
❖ Around day 13, the pituitary gland secretes LH
❖ Which causes ovulation to occur
❖ The Graafian follicle develops into corpus luteum
❖ Which secretes progesterone
❖ High level of progesterone inhibits the secretion of FSH
❖ So that overlies are no longer stimulated to release more follicles
❖ If fertilisation doesn’t occur the corpus luteum degenerates
❖ Secretion of progesterone stops
❖ The pituitary gland/hypophisis is no longer inhibited in its secretion of FSH
❖ The thickening of endometrium is no linger maintained
❖ Endometrium is then shed with blood (after shrinking and bursting of corpus luteum)

Note : Know functions of placenta as this process is capable of carrying 8
marks based on roles played by placenta.
Example : Describe the role of FSH and progesterone in menstrual cycle as
well as the role of placenta during pregnancy.
Hint: write menstrual cycle as it is but fusion occurs and 7-8
roles/functions of placenta.
❖ Allow movement of dissolved food substances, oxygen and antibodies
❖ From the mother to the foetus
❖ Allow excretory products
❖ To diffuse from foetus to the mother
❖ Act as barrier
❖ To prevent movement of drugs from mother to foetus
❖ It also secretes progesterone
❖ To maintain pregnancy