the menstrual cycle

Question 1

what are they key hormones of the menstrual cycle and where are they produced

Answer 1

1) FSH (follicle-stimulating hormone) - anterior pituitary gland
2) LH (luteinising hormone) - anterior pituitary gland
3) oestrogen - ovary
4) progesterone - ovary

Question 2

what are the two phases of the menstrual cycle and when do they occur

Answer 2

phase one- follicular phase day 0-14

phase two- luteal phase day 14-end

Question 3

outline the follicular phase of the menstrual cycle

Answer 3

1) Day 0 the conc of all hormones is low
2) the hypothalamus secretes GnRH which stimulates the anterior pituitary gland to release FSH and a small amount of LH
3) FSH stimulates the development of the primary follicles in the ovary as well as the thecal cells of the Graafian follicle to produce oestrogen
4) oestrogen causes the rebuilding of the endometrium and inhibits the FSH secretion as well as stimulating LH secretion

Question 4

what is the main role of the hormone LH

Answer 4

to induce ovulation on day 14

the high conc of LH causes the Graafian follicle to release the secondary oocyte

Question 5

outline the luteal phase of the menstrual cycle

Answer 5

1) after ovulation the Graafian follicle is retained in the ovary as the corpus luteum which produces both progesterone and oestrogen
2) progesterone and oestrogen both inhibit the production of FSH and LH reducing their conc
3) the progesterone stimulates the endometrium to thicken and remain in place

Question 6

Describe what happens if implantation doesn’t occur

Answer 6

1) the falling conc of FSH and LH causes the corpus luteum to break down which occurs within 14 days if no embryo is present
2) breakdown of the corpus luteum means progesterone production decline causing the endometrium to shed
3) as oestrogen is low it no longer inhibits FSH production the the cycle will restart

Question 7

what is the main role of FSH

Answer 7

stimulate the development of primary follicles in the ovary

stimulate the thecal cells of the Graafian follicle to secrete oestrogen

Question 8

what is the main role of oestrogen

Answer 8

• trigger the rebuilding of the endometrium
• inhibit FSH secretion
• stimulates LH production

Question 9

what is the main role of progesterone

Answer 9

• maintain the newly built endometrium