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RDS Test 1 > B8.016 Physiology of the Pregnancy > Flashcards

B8.016 Physiology of the Pregnancy Flashcards

1
Q

goal of cyclicity within HPG axis?

A
  1. prepare a fertilizable oocyte
  2. establish a uterine environment that promotes:
    - gamete movement (primarily via estrogen)
    - implantation (progesterone)
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2
Q

when is the oocyte viable

A

18 hr following ovulation

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3
Q

what occurs to stimulate luteolysis?

A

decreased sensitivity to LH
loss of blood start
decreased P4 and E2
leads to apoptosis

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4
Q

describe the movement of the conceptus

A

resides in oviduct/fallopian tube for 3 days

resides within uterus for 3 days prior to attachment of blastocyst to uterine wall

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5
Q

when does implantation occur

A

day 6-7

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6
Q

follicular phase overview

A

estrogen predominates
gland mitosis
endometrial sensitization

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7
Q

luteal phase overview

A

progesterone dominates and causes changes in the endometrial stroma

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8
Q

what is pre-decidualization

A

p4 dependent transformation of the cells

uterine secretions help nourish the blastocyst since it is in an avascular environment

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9
Q

decidualization

A

further differentiation of the endometrium which is associated with implantation

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10
Q

roles of decidualization

A
  1. controls invasion
  2. nutrition
  3. prevents immune rejection
  4. Prolactin secretion
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11
Q

estrogen function on uterus

A

proliferation

myometrium (gamete movement)

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12
Q

estrogen function on other sites in the body

A

vagina/cervix (mucous)
liver (increased binding protein production)
water retention
anabolic

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13
Q

progesterone function on uterus

A

development of glands and vasculature
myometrium
decidua cells

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14
Q

progesterone function on other sites

A

vagina/cervix (mucous)

catabolic

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15
Q

for how long is the blastocyst in a hypoxic environment?

A

first 12 weeks
small amount of blood surrounding the blastocyst, but not highly oxygenated yet
communication from lacunae filled with maternal blood

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16
Q

where is fetal circulation located at the invasion site?

A

within the villous tree

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17
Q

where is the maternal circulation located at the invasion site

A

intervillous space

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18
Q

what comprises the fetal circulation?

A

umbilical vein carried oxygenated blood to the fetus

umbilical artery carries deoxygenated blood to the placenta

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19
Q

function of syncytiotrophoblast layer

A

transport of nutrients
endocrine- production of CG, and PL
immune barrier

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20
Q

functional components of the placenta

A
  1. cytotrophoblasts: stem cells which fuse to generate a multinucleated layer of cells
  2. anchoring villous, columns of cytotrophoblasts
  3. invasive cytotrophoblasts
  4. syncytiotrophoblasts
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21
Q

function of invasive cytotrophoblasts

A

tap into maternal vasculature (spiral arteries) after week 12 of gestation
decidua help in controlling depth of invasion

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22
Q

function of anchoring villi

A

cytotrophoblasts replace the maternal endothelium and degrade the surrounding smooth muscle (decreased vascular resistance)

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23
Q

how do cytotrophoblasts remodel spiral arteries?

A

surround arteries

increase volume and decrease vascular resistance

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24
Q

what types of substances are transported across the placenta/trophoblast barrier?

A

O2
CO2
nutrients
waste

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25
Q

why is CG produced by syncytiotrophoblasts?

A

prevents mother from beginning another menstrual cycle
in maternal serum 7-9 days following surge of LH
binds to LH receptors and stimulates P4 production from corpus luteum (rescues)
**establishment and maintenance of pregnancy

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26
Q

CG half life

A

hours to days

highly glycosylated

27
Q

how does progesterone impact gonadotropes

A

suppresses LH secretion

first 6-8 weeks of gestation are relatively independent of gonadotropin support from the pituitary

28
Q

placental lactogen

A

produced by placenta/trophoblast

starts low and correlates to size of placenta

29
Q

levels of pituitary GH (GH1) during pregnancy

A

decrease steadily over 20 weeks, and then flatline at almost 0 for remainder

30
Q

levels of placental GH (GH2) during pregnancy

A

rise exponentially from 5 weeks to a peak at 35 weeks and then drop slightly

31
Q

levels of IGF1 during pregnancy

A

rise from 25-35 weeks

drop slightly after 35 week mark

32
Q

where does placental steroidogenesis take place

A

Syncytiotrophoblasts

takes over for ovary at around 8 weeks as the primary P4 producer

33
Q

what enzymes does the placenta lack?

A
  1. cholesterol synthesis enzymes
    - requires maternal cholesterol transported in
  2. 17-alphaOH and 17-20 desmolase
    - no androgen production (transports P4 out to the mother and fetus for conversion to DHEA)
34
Q

what enzymes does the placenta have?

A
  1. 3beta-HSD
    - converts pregnenolone to P4
  2. aromatase
    - converts androgens to estrogens
    - DHEA-S to E1 and E2
    - 16OHDHEAS to E3
35
Q

what metabolism is controlled by the fetal adrenal?

A

conversion of pregnenolone to DHEAS

36
Q

what metabolism is controlled by the fetal liver?

A

conversion of DHEAS to 16OH DHEAS

37
Q

list all placental hormones and their origins

A

P4: maternal cholesterol
E2 & E1: maternal and fetal DHEA-S
E3: fetal (only) 16-OH DHEAS

38
Q

estrogen potency

A

estradiol > estrone > estriol

39
Q

why is P4 particularly important in pregnancy?

A

suppresses uterine contractility

antagonizes estrogen actions

40
Q

why is DHEA sulfated in the fetal adrenal?

A

inactivates it within the fetus so the fetus is not exposed to high levels of androgens during gestation

41
Q

cortisol levels in fetal development

A

low prior to 30 wk of gestation

42
Q

placental enzymes

A

sulfatase: removes sulfate from fetal DHEA
3BHSD: makes P4
aromatase: E1, E2
17BHSD: E3

43
Q

hormonal control of myometrial contraction for labor

A

labor requires organized contractions (electrical activity) within the myometrium; this is achieved via gap junctions
-inhibited by P4, stimulated by estrogens

44
Q

hormonal control of cervical maturation

A

collagen breakdown

-inhibited by P4, stimulated by E, relaxin, PGE2

45
Q

relaxin

A

secreted by CL/decidua/placenta: inhibits myometrial contractility
induces collagenase activity, softens pelvic joints and the cervix canal (prep for birth)

46
Q

estrogens in labor and delivery

A

stimulates uterine contractions (gap junctions)
stimulates PGF2a synthesis
induces expression of oxytocin receptors (increased response)

47
Q

prostaglandins in labor and delivery

A

PGI2- vasodilator

PGF2a- stimulates cervix softening and uterine contractions

48
Q

oxytocin in labor

A

stimulates uterine contractions
constricts blood vessels
regulated by a neuroendocrine reflex loop

49
Q

most prominent stimuli leading to release of oxytocin

A
  1. suckling

2. uterine contractions in parturition

50
Q

oxytocin Ferguson reflex positive feedback loop

A

CNS > supraoptic/paraventricular nuclei > posterior pituitary > oxytocin > uterus > contractions > stretch > back to hypothalamic nuclei

51
Q

2 main functions of oxytocin

A
  1. stimulate myoepithelial cells surrounding alveoli of the mammary glands (promotes milk let down)
  2. stimulate myometrial contractility (labor)
52
Q

development of mammary glads in pregnancy

A

development during pregnancy, regulated by hormones produces during pregnancy

53
Q

estrogen function on mammary gland

A

duct growth
fat deposition
INHIBITS milk synthesis

54
Q

progesterone function on mammary gland

A

growth of the alveolar epithelium

INHIBITS milk synthesis

55
Q

insulin function on mammary gland

A

gland growth and development

56
Q

glucocorticoid function on mammary gland

A

gland growth and development

milk protein synthesis

57
Q

Prolactin, GH, PL function on mammary gland

A

gland growth

milk synthesis

58
Q

oxytocin function on mammary gland

A

contraction of myoepithelial cells (secretion)

59
Q

hormone control of mammary glands during parturition

A

fall in P4 and E (placenta is gone), maintenance of prolactin secretion
removes the block P4 and E have on milk synthesis

60
Q

hormone control of mammary glands during lactation

A

prolactin stimulates milk secretion and lipase activity

oxytocin propels milk through the ducts to the nipples

61
Q

why does prolactin cause amenorrhea?

A

inhibits GnRH, thus suppresses the HPG axis

62
Q

what causes hyperprolactinemia

A

usually associated with a pituitary tumor

-often effectively treated with a dopamine agonist

63
Q

hypothalamic control of prolactin secretion

A

usually tonically inhibited

dopamine seems to be the main player in this inhibitory control

64
Q

oxytocin suckling positive feedback loop

A

CNS > supraoptic/paraventricular nuclei > posterior pituitary > oxytocin > mammary glands > milk let down > suckling > back to CNS

RDS Test 1 (22 decks)

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