Endocrinology of OBGYN

Question 1

what are the two phases of the ovarian cycle? when does each begin?

Answer 1

follicular - begins day 1

luteal - begins after ovulation

Question 2

what are the features of the follicular phase

• what forms / develops
• what happens to the endometrium
• what follows?

Answer 2

• follicle development
• endometrial proliferation
• follicular phase is followed by ovulation

Question 3

what are the features of the luteal phase?

• what forms / develops
• what happens to the endometrium
• what follows?

Answer 3

• corpus luteum forms
• endometrial differentiation
• followed by menses

Question 4

when does FSH rise in the ovarian cycle?

Answer 4

early in follicular phase, and also at ovulation

Question 5

what is the role of estrogen during the follicular phase on the anterior pituitary?

Answer 5

negative feedback

Question 6

what is the role of estrogen during mid-cycle on the anterior pituitary?

Answer 6

36 hours of relatively high estrogen concentrations exert positive feedback at the level of the anterior pituitary

Question 7

what is the role of estrogen (and progesterone) during the luteal phase on the anterior pituitary?

Answer 7

negative feedback

Question 8

when does inhibin A rise? what is its role?

Answer 8

luteal phase

negative feedback

Question 9

the inhibins are synthesized by what cells of the ovary?

Answer 9

granulosa cells

Question 10

what is an important role of inhibin B

Answer 10

regulation of FSH

Question 11

follicular phase is associated with what hormone?

Answer 11

estrogen

Question 12

theca cells synthesize androstenedione in response to what hormone?

Answer 12

LH

Question 13

where is androstenedione converted to estradiol? what regulates this process?

Answer 13

granulosa cells

FSH regulates this conversion

Question 14

follicular phase has a role for what two hormones?

Answer 14

FSH and LH

Question 15

early to mid follicular phase - what is estrogen doing?

Answer 15

applying negative feedback on HPG axis

Question 16

why does estrogen continue to rise during the follicular phase despite negative feedback on LH and FSH?

Answer 16

presence of more theca cells, and more secretions from those theca cells

also increased sensitivity, so more steroid production

Question 17

at day 14, what induces ovulation? what is absolutely required?

Answer 17

surge in LH and FSH

LH is absolutely required

Question 18

what hormone is responsible for the rise in basal body temperature during ovulation?

Answer 18

progesterone

Question 19

the corpus luteum forms from what cell types?

Answer 19

thecal 
granulosa 
fibroblast 
endothelial 
immune cells 
lipids

Question 20

when does the corpus luteum reach maturity?

Answer 20

7-8 days following ovulation

Question 21

what is the change in the regulation from the follicular phse to the luteal phase?

Answer 21

LH becomes key regulator in the luteal phase - theca cells become more responsive to LH

Question 22

what is the key difference in granulosa cells during the luteal phase?

Answer 22

• LH now regulates
• progesterone synthesis is now occurring
• increased in uptake of cholesterol

Question 23

during the luteal phase, what hormone regulated the differentiation and secretory development of uterine endometrium?

Answer 23

progesterone

Question 24

what are the key endometrial changes during the luteal phase?

Answer 24

• increased complexity of vascular and glandular structures
• accumulation of substances in glands
• deposition of lipids and glycogen in stromal cells
• increased blood supply

Question 25

what allows for the ovarian cycle to reset?

Answer 25

- regression of corpus luteum - decline in steroid cynthesis - decrease in negative feedback on anteior pituitary (concentrations of LH and FSH rise)

Question 26

what are the steps of implantation?

Answer 26

1. hatching 2. apposition 3. adhesion 4. invasion

Question 27

what constitutes 'hatching' during implantation and formation of the palcenta?

Answer 27

breakdown of zona pellucida

Question 28

what constitutes 'apposition' during implantation and formation of the placenta?

Answer 28

trophoblastic cells of the blastocyst make contact with endometrium

Question 29

what constitutes 'adhesion' during implantation and formation of the placenta? what mediates this process?

Answer 29

integrin mediated attachment between trophoblast and stromal cells (decidual cells) of the endometrium

Question 30

what constitutes 'invasion' during implantation and formation of the placenta?

Answer 30

- trophoblast differentiates into cytotrophoblast and syncitiotrophoblast - syncitiotrophoblasts send out protrusions and invade endometerium

Question 31

what are the steps of placenta formation?

Answer 31

1. invading syncitiotrophoblast breaks through maternal veins and arteries 2. allows for pools of maternal blood to interface with syncytiotrophoblasts 3. primary chorionic villi form 4. within villi, capillaries form

Question 32

what are the components of the fetal placenta?

Answer 32

- syncytiotrophoblasts - cytotrophoblasts - mesenchyme - fetal blood vessels

Question 33

what is contained in the intervillous space?

Answer 33

blood trapped between fetal villous and maternal endometrium

Question 34

what are the components of the maternal placenta?

Answer 34

- decidual cells | - maternal arteries and veins

Question 35

what happens to the corpus luteum upon implantation?

Answer 35

- placental derived hCG stimulates ovarian steroidogenesis | - secretes relaxin to inhibit myometrial contractions

Question 36

after week 8 following implantation, maintenance of pregnancy is dependent upon what hormones? what are their roles?

Answer 36

progesterone - suppress uterine contractions, inhibit PG production, impact immune response estrogen - stimulate uterine growth, thicken vaginal epithelium, growth, and development of mammary epithelium

Question 37

what are the physiological roles of hCG? where does it bind?

Answer 37

- bind LH receptors - maintain corpus luteum - maintain ovarian steroid production needed for first 7-8 weeks of gestation

Question 38

where is hCG produced? when is it secreted? when does it peak?

Answer 38

- syncytiotrophoblast (fetal placenta-derived) - secreted around week 6 of pregnancy - increases throughout pregnancy

Question 39

what are the physiological roles of human placental lactogen (hPL)?

Answer 39

- fetal metabolism - fetal growth and development - stimulates production of IGF, insulin, adrenocortical hormones, surfactant

Question 40

where is hPL produced? when is it secreted? when does it peak?

Answer 40

- syncytiotrophoblast - secreted around week 6 of pregnancy - increases throughout pregnancy

Question 41

what are the physiological roles of CRH?

Answer 41

- onset of labor - production of PGs - maintain blood flow in placenta

Question 42

where is CRH produced? when does it peak?

Answer 42

- syncytiotrophoblast and trophoblast | - increases throughout pregnancy and peaks during labor

Question 43

what are the physiological roles of progesterone and 17-hydroxyprogesterone?

Answer 43

- inhibit PG production - suppress uterine contractions - modulate immune response

Question 44

where is progesterone produced during pregnancy? what is required for its production?

Answer 44

- first 8 weeks, produced by corpus luteum under control of hCG - after 8 weeks, produced by syncytiorophoblast - requires use of maternal LDL

Question 45

what are the physiological roles of DHEA?

Answer 45

substrates for estrogen synthesis

Question 46

where is DHEA produced?

Answer 46

- maternal adrenal gland - fetal adrenal gland - fetal liver