PED1003/L20 Female Sex Hormones

Question 1

Describe how nuclear hormone receptors work. (6)

Answer 1

Steroid hormone enters cell
Binds to steroid hormone receptor
Dissociates and dimerises
Translocate to the nucleus
Recruits RNA polymerase II
Transcription & translation

Question 2

What is the follicular phase?

Answer 2

Day 1-14 in which the follicle is matured

Question 3

What is the luteal phase?

Answer 3

Day 14-28 in which an environment is created to promote implantation

Question 4

Give the role of oestrogen in fertility. (3)

Answer 4

Growth of ovarian follicles
Endometrial growth
Increase in tubal motility and uterine contractions

Question 5

Give the role of oestrogen in lactation. (2)

Answer 5

Stimulation of duct growth
Inhibits milk let-down (prolactin)

Question 6

Give the role of progesterone in fertility. (3)

Answer 6

Endometrial receptivity
Decrease in Fallopian tube motility
Decrease in uterine contractions

Question 7

Give the role of oestrogen in secondary sexual characteristics. (3)

Answer 7

Breast development
Female habitus (skeletal, skin, metabolism)
Development of external genitalia

Question 8

Give the role of progesterone in lactation. (2)

Answer 8

Stimulation of lobuloalveolar development
Inhibits milk let-down (prolactin)

Question 9

Describe the hypothalamic-pituitary-ovarian axis. (3)

Answer 9

Hypothalamus - GnRH pulsatile release
Anterior pituitary - LH, FSH
Ovary - oestrogen, progesterone

Question 10

What is the role of the enzyme aromatase?

Answer 10

Converting androgen to oestrogen, driven by FSH

Question 11

What hormone does oestrogen inhibit?

Answer 11

FSH

Question 12

What hormone does progesterone inhibit? (3)

Answer 12

GnRH, FSH & LH

Question 13

Describe the follicular phase of the ovarian cycle. (9)

Answer 13

FSH increasing due to low ovarian hormone production
FSH aids follicular development
Follicles produce oestrogen
High concentration of oestrogen >48h
Positive feedback from increased oestrogen initiated the LH surge
LH surge induces ovulation
Remainder of follicular phase becomes luteinised
Secretes P & O
If not pregnant, CL regresses and decrease in P & O

Question 14

What occurs after ovulation if no fertilisation occurs? (4)

Answer 14

Corpus luteum regression
P & O levels drop
Endometrium can not be maintained - menstruation
Lack of P means GRH, FSH & LH secretion

Question 15

What occurs after ovulation if fertilisation and implantation occurs? (5)

Answer 15

Ovum secretes human chorionic gonadotrophin (HCG)
Corpus luteum continues to secrete progesterone
Maintains endometrium and pregnancy
Thicken cervical mucus
Inhibits further secretion of GRH, FSH, LH preventing further follicles developing

Question 16

Give an example of an ER and PR agonist.

Answer 16

GnRH, FSH, LH all required to induce follicle formation and ovulation
O & P required to feedback on hypothalamus and pituitary and inhibits further follicles being formed

Question 17

Give an example of a PR antagonist.

Answer 17

Progesterone require to maintain pregnancy

Question 18

Describe how the combination pill works. (2)

Answer 18

Oestrogen inhibits secretion of FSH via negative feedback, preventing development of ovarian follicle and blocks ovulation by blocking FSH peak
Progesterone inhibits LH by blocking LH surge and makes cervical mucus less suitable for passage of sperm

Question 19

Describe how the progesterone only pill works. (2)

Answer 19

Inhibits LH and thickens mucus
Blocks ovulation by blocking LH surge
FSH peak still occurs

Question 20

Describe how the contragestation (abortion pill) works. (2)

Answer 20

Progesterone antagonist
Terminates pregnancy at level of endometrium

Question 21

Describe how hormone antagonists work. (2)

Answer 21

Tumours arising in hormone sensitive tissues may be hormone-dependent
Growth can be inhibited by hormone antagonists

Question 22

Give an example of a selective oestrogen receptor modulator (SERM).

Answer 22

Tamoxifen

Question 23

Give an aromatase inhibitor.

Answer 23

Anastrozole

Question 24

Describe how tamoxifen works. (4)

Answer 24

Binds to ER to form a dimer
Transported from cytosol to nucleus
Binds DNA to form unstable complex
Hormonal growth signal switched off

Question 25

Overexpressed estrogen receptors are present in what percentage of breast cancers?

Answer 25

75%