Reproduction - pregnancy

Question 1

Endocrine function of syncytiotrophoblasts

Answer 1

hCG and hPL

Question 2

hCG

Answer 2

• human chorionic gonadotropin (binds to LH receptors on corpus luteum; keeps it viable)
• what pregnancy tests detect in urine
• rapid rise in HCG causes morning sickness
• hCG stimulates leydig cells and adrenal cortex in fetus
• has negative fxn on HPG axis

Question 3

hPL

Answer 3

Human placental lactogen
Similar to GH and prolactin
GH-like : counterregulatory to insulin (lipolytic), mobilizes glucose for fetal use, stimulates IGF-I in fetus

Prolactin-like
Stimulates mammary gland development in mother

Question 4

Pregnancy is a (hormone) resistant state?

Answer 4

Insulin

Question 5

hPL effects on maternal glucose handling

Answer 5

hPL can be found in higher levels in maternal than fetal circulation; not essential for maintaining pregnancy so it is more important in mother than fetus. It is anti-insulin and helps mobilize glucose and other nutrients from mother to fetus

Question 6

What two steroid hormones produced by the placenta help reduce insulin sensitivity in mother

Answer 6

Estrogen and progesterone

Question 7

Gestational diabetes

Answer 7

Caused by anti-insulin effects of hPL, progesterone, prolactin, and cortisol

Usually resolves at end of pregnancy, but seems to be a risk factor for T2DM

At risk most: Women >25, family history of diabetes, and T2DM

Question 8

When fully formed, what are the functions of the placenta (4)

Answer 8

Gut (supplies nutrients ; occurs by diffusion/facilitated diffusion)
Lung (gas exchange – helped by fetal hemoglobin)
kidney (regulating fluid volume and waste disposal)
endocrine gland (hPL, estrogen, progesterone, hCG)
Functions to remove waste products such as urea, creatinine, and co2.

Provides a semi-protective barrier

Question 9

Why is the placenta an imperfect endocrine gland

Answer 9

it lacks critical enzymes to complete many steps in steroid hormone biosythesis; protects fetus from steroids from mother like cortisol and high gonadal steroid hormone levels.

Question 10

What can the placenta NOT do?

Answer 10

Synthesize cholesterol (relies on maternal LDL, does NOT use StAR to get cholesterol)

Convert progesterone into other steroids (no CYP17) –> progesterone is made into androgens and other steroids by fetus

Cannot make estriol - fetal LIVER makes an enzyme (CYP3A7) to convert DHEAS which can be downstream converted into estriol, which is the main circulating estrogen during pregnancy

Question 11

What part of the fetus makes estriol

Answer 11

fetal liver - uses CP3A7 converts DHEAS to 16-hydroxyl DHEAS - this is downstream converted into estriol by placenta (E3) which is the main circulating estrogen in pregnancy

Question 12

What “hypothalamic” releasing hormone is released by placenta

Answer 12

CRH – this release will increase with gestational age and has been inked to gestational length

Question 13

Does fetal pituitary secrete ACTH?

Answer 13

Yes – but it does NOT have a negative feedback effect – instead it stimulates more CRH release in a positive feedback amplification release.

Question 14

What are the 3 zones of the fetal adrenal gland?

Answer 14

Definitive zone, transitional zone, and fetal zone

Question 15

definitive zone of fetal medulla

Answer 15

becomes zona glomerulosa, begins making aldosterone near birth

Question 16

transitional zone in fetal adrenal gland

Answer 16

becomes zona fasiculata and begins making cortisol at about 6 months gestation

Question 17

Fetal zone of fetal adrenal

Answer 17

Largest zone- becomes zona reticularis, makes androgens throughout gestation

Question 18

Through the MAJORITY of pregnancy, what generates the estrogen and progesterone needed to maintain the pregnancy?

Answer 18

The placenta, because the corpus luteum cannot keep up with the high levels required to do this – takes over after ~8weeks

However – estrogen cannot be synthesized independently by the placenta because it lacks CYP17 ability to convert progesterone –> androgens

Question 19

Relaxin

Answer 19

Produced by corpus luteum due to hCG and by placenta
Inhibits myometrial contractions (ensures uterine quiescence in early pregnancy)
Relaxes pelvic bone ligaments and soften cervix to prepare in parturition

Question 20

Prolctin

Answer 20

Made from MATERNAL pituitary (not placenta)
Essential for mammotrophic effects of E2 and p4
prepares boobies for lactation
E2 stimulates growth of lactotrophs and increases PRL secretion

Question 21

Changes in Cardiovascular system in pregnancy (effect of MAP, pulmonary pressures, venous pressure increases, TPR)

Answer 21

MAP decreases, TPR decreases more than CO increases
Pulmonary pressure stays the same, off setting increase in volume with a decrease in resistance
venous pressure increases by 150% due to venous distention

Question 22

Regional blood flow in pregnancy

Answer 22

uterus receives 30% of cardiac output; skin flow increases to maintain body temperature, kidney blood flow increases and GFR increases

Question 23

Blood in pregnancy

Answer 23

increase blood volume (primarily in 2nd trimester), body anticipates hemorrhage; both plasma and RBC increase with net decrease in hematocrit

Question 24

Respiratory changes in pregnancy

Answer 24

Diaphram elevation (5in)
Tidal volume increase, increases alveolar ventilation

Question 25

GI changes in pregnancy

Answer 25

Decrease GI motility to absorm more nutrients, LES tone is decreased (greater reflux)

Question 26

Endocrine Fxn in maternal body during pregnancy

Answer 26

Changed with suppression of maternal HPG axis is suppressed due to the placental sex steroids and there is significant growth of the lactrophs and net increase in PRL, which inhibits the GnRH even more

Question 27

Metabolic changes in pregnancy

Answer 27

1st half of pregnancy- mother is in anabolic state with normal or increased sensitivity to insulin and increased fat deposition and glycogen storage; promotes breast growth in mother and allows stockpiling of nutrients to meet demands of enlarging fetus 2nd half - you get insulin resistance, accelerated starvation due to catabolic state characterized by insulin resistance; increase in plasma glucose and FA levels mediated by hPL (why pregnant ladies can develop gestational diabeties)

Question 28

Parturition -- what hormones mediate this

Answer 28

Progesterone, E2, cortisol, relaxin, oxytocin, CRH, prostaglandins, catecholamines. And, most importantly: Decreased ratio of progesterone : Estrogen

Question 29

Stages of labor

Answer 29

Phase 0 - quiescent uterus kept inactive by progesterone Phase 1 - Actiation of uterus - release of inhibitory mechanism and activation of factors that increase uterine activity; increased activation of fetal HPA axis and peak in fetal CRH levels Phase 2- Active uterine contractions faciliated by icnreased PGs, oxy, and CRH respond in positive feedback loop. Phase 3- expulsion of fetus from uterine compartment and expulsion of placenta

Question 30

Ferguson reflex

Answer 30

pressure exerted from fetus on cervix that stimulates oxytocin and leads to the positive feedback cycle on uterine contractions

Question 31

Phase 2 changes in hormones

Answer 31

Decreased P4:E2 ratio; releases PGs E2 inreases oxytocin receptors in uterus CRH increases fetal HPA axis, which also increases E2 Uterine contractions stimulate oxytocin which stimulates more uterine contractions Oxytocin stimulates more prostaglandin release from uterus

Question 32

Lactation is initatied after delivery by what?

Answer 32

Decrease in P4 and E2 because placenta is no longer present

Question 33

What sustains milk secretion

Answer 33

repeated transient hyperprolactinemia - suckling stimulates prolactin release

Question 34

Prolactin does what to reproductive function

Answer 34

decreases by inhibiting GnRH

Question 35

Behaviorally, what does prolactin also do to the mother?

Answer 35

stimulate maternal behavior during pregnancy and after parturition

Question 36

What is the first milk produced called

Answer 36

colostrum, and it's low fat milk (it's the great value 1%)

Question 37

what hormones are essential for continued milk production

Answer 37

prolactin, cortisol, and insulin

Question 38

What is the reflex that oxytocin induces for breastfeeding

Answer 38

milk let down via contraction of myoepithelial cells and alveoli and smooth muscle leads to this -- can be caused by infant crying

Question 39

What inhibits lactation DURING pregnancy

Answer 39

high progesterone

Question 40

Hormonal birth control: What does the progestational part of the hormone pill does what to hormone secretion? What does the estrogenic hormone in the pill inhibit?

Answer 40

Progestational hormone Prevents LH secretion (estrogenic hormone) Estrogenic hormone inhibits FSH release, stabilizes endometrium, pogentiates progestin action