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

B8.016 Physiology of the Pregnancy Flashcards

(64 cards)

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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
why is CG produced by syncytiotrophoblasts?
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**
26
CG half life
hours to days | highly glycosylated
27
how does progesterone impact gonadotropes
suppresses LH secretion | first 6-8 weeks of gestation are relatively independent of gonadotropin support from the pituitary
28
placental lactogen
produced by placenta/trophoblast | starts low and correlates to size of placenta
29
levels of pituitary GH (GH1) during pregnancy
decrease steadily over 20 weeks, and then flatline at almost 0 for remainder
30
levels of placental GH (GH2) during pregnancy
rise exponentially from 5 weeks to a peak at 35 weeks and then drop slightly
31
levels of IGF1 during pregnancy
rise from 25-35 weeks | drop slightly after 35 week mark
32
where does placental steroidogenesis take place
Syncytiotrophoblasts | takes over for ovary at around 8 weeks as the primary P4 producer
33
what enzymes does the placenta lack?
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
what enzymes does the placenta have?
1. 3beta-HSD - converts pregnenolone to P4 2. aromatase - converts androgens to estrogens - DHEA-S to E1 and E2 - 16OHDHEAS to E3
35
what metabolism is controlled by the fetal adrenal?
conversion of pregnenolone to DHEAS
36
what metabolism is controlled by the fetal liver?
conversion of DHEAS to 16OH DHEAS
37
list all placental hormones and their origins
P4: maternal cholesterol E2 & E1: maternal and fetal DHEA-S E3: fetal (only) 16-OH DHEAS
38
estrogen potency
estradiol > estrone > estriol
39
why is P4 particularly important in pregnancy?
suppresses uterine contractility | antagonizes estrogen actions
40
why is DHEA sulfated in the fetal adrenal?
inactivates it within the fetus so the fetus is not exposed to high levels of androgens during gestation
41
cortisol levels in fetal development
low prior to 30 wk of gestation
42
placental enzymes
sulfatase: removes sulfate from fetal DHEA 3BHSD: makes P4 aromatase: E1, E2 17BHSD: E3
43
hormonal control of myometrial contraction for labor
labor requires organized contractions (electrical activity) within the myometrium; this is achieved via gap junctions -inhibited by P4, stimulated by estrogens
44
hormonal control of cervical maturation
collagen breakdown | -inhibited by P4, stimulated by E, relaxin, PGE2
45
relaxin
secreted by CL/decidua/placenta: inhibits myometrial contractility induces collagenase activity, softens pelvic joints and the cervix canal (prep for birth)
46
estrogens in labor and delivery
stimulates uterine contractions (gap junctions) stimulates PGF2a synthesis induces expression of oxytocin receptors (increased response)
47
prostaglandins in labor and delivery
PGI2- vasodilator | PGF2a- stimulates cervix softening and uterine contractions
48
oxytocin in labor
stimulates uterine contractions constricts blood vessels regulated by a neuroendocrine reflex loop
49
most prominent stimuli leading to release of oxytocin
1. suckling | 2. uterine contractions in parturition
50
oxytocin Ferguson reflex positive feedback loop
CNS > supraoptic/paraventricular nuclei > posterior pituitary > oxytocin > uterus > contractions > stretch > back to hypothalamic nuclei
51
2 main functions of oxytocin
1. stimulate myoepithelial cells surrounding alveoli of the mammary glands (promotes milk let down) 2. stimulate myometrial contractility (labor)
52
development of mammary glads in pregnancy
development during pregnancy, regulated by hormones produces during pregnancy
53
estrogen function on mammary gland
duct growth fat deposition INHIBITS milk synthesis
54
progesterone function on mammary gland
growth of the alveolar epithelium | INHIBITS milk synthesis
55
insulin function on mammary gland
gland growth and development
56
glucocorticoid function on mammary gland
gland growth and development | milk protein synthesis
57
Prolactin, GH, PL function on mammary gland
gland growth | milk synthesis
58
oxytocin function on mammary gland
contraction of myoepithelial cells (secretion)
59
hormone control of mammary glands during parturition
fall in P4 and E (placenta is gone), maintenance of prolactin secretion removes the block P4 and E have on milk synthesis
60
hormone control of mammary glands during lactation
prolactin stimulates milk secretion and lipase activity | oxytocin propels milk through the ducts to the nipples
61
why does prolactin cause amenorrhea?
inhibits GnRH, thus suppresses the HPG axis
62
what causes hyperprolactinemia
usually associated with a pituitary tumor | -often effectively treated with a dopamine agonist
63
hypothalamic control of prolactin secretion
usually tonically inhibited | dopamine seems to be the main player in this inhibitory control
64
oxytocin suckling positive feedback loop
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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