Hormones in pregnancy

Question 1

Which structure produces progesterone in early pregnancy

Answer 1

corpus luteum

Question 2

If egg doesn’t implant/After week 13 of gestation what structure does corpus lute regress to form?

Answer 2

Corpus albicans

Question 3

What maintains the function of the corpus luteum

Answer 3

HCG secreted during pregnancy

Question 4

In the luteal phase prior to pregnancy what hormone does the corpus luteum secrete?

Answer 4

Progesterone and oestrogen

Question 5

Describe cycle of GnRH release

Answer 5

There is pulsatile release of GnRH from arcuate nucleus of the hypothalamus and travels to anterior pituitary. When pulse rate lower FSH is released (beginning of cycle). When pulse rate is higher LH is released (mid-cycle around ovulation)

Question 6

Describe follicular phase of ovarian cycle

Answer 6

First stage where follicles are developed. Begins with initiation of menstrutation (lasts approx 14 days). As follicles mature they produce oestrogen. As oestrogen increases it causes FSH to decrease. Immediately before ovulation the rate oestrogen is released increases and stimulates LH surge which triggers ovulation

Question 7

Describe ovulation

Answer 7

Release of mature ovum from ovary caused by LH surge (36hrs after onset and 12hrs after peak of LH surge).

Question 8

Explain the surge in LH during ovulation

Answer 8

Oestrogen normally suppresses LH secretion by negative feedback to anterior pituitary via GnRH-1. But when oestrogen levels are high it acts on a different subset of cells in hypothalamus that produce GnRH-2 to cause an increase in LH production via positive feedback.

Question 9

Describe the luteal phase of ovulation

Answer 9

As follicles mature they produce oestrogen. As oestrogen levels increase it causes FSH to decrease (-ve feedback). Corpus luteum forms from the follicle of the released ovum which secretes progesterone and oestrogen. Progesterone and oestrogen levels then decrease causing hypothalamus and pituitary to increase GnRH and FSH. In late luteal phase low ovarian hormone production causes GnRH to release FSH and FSH level increases (so follicles can mature)

Question 10

Describe the hypothalamic-pituitary-ovarian axis

Answer 10

Hypothalamus secretes gonadotropin releasing hormone (GnRH) that travels to the anterior pituitary. Thee anterior pituitary releases FSH and LH causing ovaries to stimulate ovarian cycle. Ovaries then release oestrogen and progesterone that causes changes of endometrium in uterus (endometrium cycle)

Question 11

Where is hCG produced?

Answer 11

Produced by trophoblasts (initially syncytiotrophoblasts) which eventually form placenta

Question 12

Functions of hCG

Answer 12

Maintains corpus lutteur and promotes quiescence (stops uterus contracting). Also replaces LH in promoting progesterone (due to its longer half life than LH) and also in pregnancy testing

Question 13

6 functions of oestrogen

Answer 13

Inhibits FSH and LH. Stimulates breast growth and uterine growth. Softens the cervix and relaxes joints and ligaments.

Question 14

4 functions of progesterone

Answer 14

Inhibits FSH and LH. Relaxes smooth muscle (bu inhibiting oxytocin receptors) and maintains endometrial lining (also increases breast cancer development)

Question 15

Describe function of Human placental lactogen

Answer 15

Increases fatty acids and insulin, decrease in maternal blood glucose so more glucose available for fetus

Question 16

Describe function of relaxin

Answer 16

Relaxes maternal structure in prep for maternal action. i.e allows softening in dilation of cervix and allows pelvic ligaments to stretch

Question 17

Describe function of oxytocin

Answer 17

Drives contraction of uterus

Question 18

Describe function of prolactin

Answer 18

Promotes lactation

Question 19

State 4 hormones produced by the placenta

Answer 19

Human placental lactogen. Relaxin. Oxytocin. Prolactin.

Question 20

Which hormone stimulates the alveolar/lobules (milk secreting tissue) to proliferate

Answer 20

Progesterone

Question 21

What influences duct proliferation

Answer 21

Oestrogen, growth hormones and glucocorticoids

Question 22

Production of progesterone by placenta

Answer 22

Maternal 3-beta HSD cholesterol is converted into progesterone for both mother and foetus by placenta.

Question 23

Production of oestrogen by placenta

Answer 23

Fetus can use cholesterol and progesterone to make DHEA which the placenta can convert to oestrogen

Question 24

Describe the two stages of luteinisation

Answer 24

1. Follicular thecae cells luteinise into theca lutein cells (which produce oestrogen precursors)
2. Follicular granulosa cells luteinise into granulosa lutein cells. These produce progesterone (and a small amount of oestrogen)

Question 25

What two cell types make up corpus luteum?

Answer 25

Theca lutein cells and Granulosa Lutein cells

Question 26

Stae 3 fertility, 2 lactation and 3 developmental functions of oestrogen

Answer 26

Fertility
1. Growth of ovarian follicles 
2. Endometrial growth
3. Increase in tubal motility and uterine contraction
Lactation
1. Stimulation of duct growth
2. Inhibits milk let-down (no inappropriate secretion)
Development of sexual characteristics
1. Breast development
2. Female habitus (skeleton, metabolism)
3. External genitalia

Question 27

State 3 fertility and 2 lactation functions of progesterone

Answer 27

Fertility
1. Endometrial receptivity (luteal phase)
2. Decrease in Fallopian tube motility
3. Decrease in uterine contractions
Lactation
1. Stimulation of lobuloalveolar development