menstrual physiology

Question 1

what stimulates the release of FSH and LH

Answer 1

gonadotrophin releasing hormone

Question 2

what does FSH do

Answer 2

initiates follicular growth

Question 3

what does LH do

Answer 3

stimulates further development of follicles

Question 4

what do FSH and LH do

Answer 4

stimulate the ovarian follicles to secrete oestrogen

Question 5

where is progesterone mainly secreted

Answer 5

by the corpus luteum

Question 6

what do progesterone and oestrogen do

Answer 6

prepare and maintain the endometrium ready for implantation

Question 7

when is the menstrual phase

Answer 7

roughly first 5 days of the cycle

Question 8

what happens in the ovaries in the menstrual phase

Answer 8

under the influence of FSH primary follicles develop into secondary follicles

Question 9

what happens in the uterus in menstrual phase

Answer 9

-a fall in oestrogen and progesterone stimulates release of prostaglandins causing uterine spiral arterioles to constrict
-the cells supplied by these arterioles die and the entire stratum functionalis of the endometrium sloughs off leaving the thin stratum basalis
-blood, tissue, mucous and epithelial cells shed from the endometrium passing through the cervix and vagina

Question 10

what phase has the main impact on cycle length

Answer 10

preovulatory phase as it varies in length the most

Question 11

what happens in the ovaries in the preovulatory phase

Answer 11

-secondary follicles secrete oestrogen
-one secondary follicle outgrows the rest to become dominant and develops into the graafian follicle

Question 12

what happens in the uterus in the preovulatory phase

Answer 12

-oestrogens released into the circulation by the growing secondary follicles and graafin follicle stimulate growth of the endometrium
-cells of the stratum basalis undergo mitosis and produce a new stratum functionalis
-endometrial thickness doubles

Question 13

when does the ovulatory phase occur

Answer 13

day 14 in a 28 day cycle (14 days before menstruation)

Question 14

what happens in the ovaries in ovulatory phase

Answer 14

-oestrogen stimulates more GnRH release
-this leads to an increase in LH and FSH release
-LH causes the rupture of the graafian follicle and expulsion of a secondary oocyte
-the oocyte is taken into the fallopian tube

Question 15

what happens in the uterus in the ovulatory phase

Answer 15

progesterone and oestrogen continue to stimulate proliferation of the endometrium

Question 16

how long does the postovulatory phase last

Answer 16

14 days with little variation

Question 17

what happens in the ovaries in the postovulatory phase

Answer 17

-the collapsed follicle becomes the corpus luteum under the influence of LH
-the corpus luteum secretes progesterone, osetrogen, relaxin and inhibin
-if fertilisation does not occur this secretory activity declines after 2 weeks and a new cyst begins

Question 18

what happens in the uterus in the postovulatory phase

Answer 18

-progesterone and oestrogen promote growth and coiling of the endometrial glands, vasculisation and further thickening of the endometrium
-endometrial glands begin to secrete glycogen

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