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FHB > Reproduction - pregnancy > Flashcards

Reproduction - pregnancy Flashcards

1
Q

Endocrine function of syncytiotrophoblasts

A

hCG and hPL

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2
Q

hCG

A
  • 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
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3
Q

hPL

A

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

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4
Q

Pregnancy is a (hormone) resistant state?

A

Insulin

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5
Q

hPL effects on maternal glucose handling

A

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

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6
Q

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

A

Estrogen and progesterone

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7
Q

Gestational diabetes

A

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

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8
Q

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

A

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

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9
Q

Why is the placenta an imperfect endocrine gland

A

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.

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10
Q

What can the placenta NOT do?

A

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

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11
Q

What part of the fetus makes estriol

A

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

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12
Q

What “hypothalamic” releasing hormone is released by placenta

A

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

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13
Q

Does fetal pituitary secrete ACTH?

A

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

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14
Q

What are the 3 zones of the fetal adrenal gland?

A

Definitive zone, transitional zone, and fetal zone

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15
Q

definitive zone of fetal medulla

A

becomes zona glomerulosa, begins making aldosterone near birth

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16
Q

transitional zone in fetal adrenal gland

A

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

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17
Q

Fetal zone of fetal adrenal

A

Largest zone- becomes zona reticularis, makes androgens throughout gestation

18
Q

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

A

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

19
Q

Relaxin

A

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

20
Q

Prolctin

A

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

21
Q

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

A

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

22
Q

Regional blood flow in pregnancy

A

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

23
Q

Blood in pregnancy

A

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

24
Q

Respiratory changes in pregnancy

A 
Diaphram elevation (5in)
Tidal volume increase, increases alveolar ventilation
25
Q

GI changes in pregnancy

A

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

26
Q

Endocrine Fxn in maternal body during pregnancy

A

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

27
Q

Metabolic changes in pregnancy

A

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)

28
Q

Parturition – what hormones mediate this

A

Progesterone, E2, cortisol, relaxin, oxytocin, CRH, prostaglandins, catecholamines.

And, most importantly:
Decreased ratio of progesterone : Estrogen

29
Q

Stages of labor

A

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

30
Q

Ferguson reflex

A

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

31
Q

Phase 2 changes in hormones

A

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

32
Q

Lactation is initatied after delivery by what?

A

Decrease in P4 and E2 because placenta is no longer present

33
Q

What sustains milk secretion

A

repeated transient hyperprolactinemia - suckling stimulates prolactin release

34
Q

Prolactin does what to reproductive function

A

decreases by inhibiting GnRH

35
Q

Behaviorally, what does prolactin also do to the mother?

A

stimulate maternal behavior during pregnancy and after parturition

36
Q

What is the first milk produced called

A

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

37
Q

what hormones are essential for continued milk production

A

prolactin, cortisol, and insulin

38
Q

What is the reflex that oxytocin induces for breastfeeding

A

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

39
Q

What inhibits lactation DURING pregnancy

A

high progesterone

40
Q

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?

A

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

FHB (54 decks)

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