The Ovarian Cycle

Question 1

What happens to the corpus luteum if the egg is fertilised

Answer 1

Corpus luteum produces HCG (human chorionic gonadotrophin) and continues to secrete progesterone to maintain the endometrium

Question 2

The effect of luteinizing hormone (4)

Answer 2

Maintenance of dominant follicle

Induce follicular maturation

Induce ovulation

Stimulate corpus luteum function

Question 3

What causes the release of anterior pituitary hormones

Answer 3

Hypothalamus releases gonadotrophic releasing hormone (GnRH)

–> LH and FSH

Question 4

What causes the surge in LH

Answer 4

Increasing plasma oestrogen secreted by dominant follicle

Question 5

Describe the negative feedback mechanism of oestrogen

Answer 5

Negative feedback control of LH and GnRH

For late follicular phase - positive control of LH surge and negative feedback of FSH

Question 6

Main hormones responsible for

1) Follicular phase (0-14)
2) Secretory phase (14-28)

Answer 6

1) Oestrogen from granuloma - late follicular phase stimulates proliferation of endometrium
2) Progesterone from corpus luteum - maintenance of secretory endometrium

Question 7

Inhibin A

Answer 7

Has intra corpus luteum actions

Negative feedback control of HPO

Question 8

Inhibin B

Answer 8

Has intra-ovarian actions

Negative feedback control of HPO

Question 9

What happens to the corpus luteum if the follicle it isn’t fertilised

Answer 9

Corpus luteum degenerates to form the corpus albicans

Plasma oestrogen and progesterone concentrations decrease

Endometrium begins to slough

FSH and LH concentrations rise

Several growing follicles are stimulated to mature