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PYSIO OB > PLACENTAL HORMONES > Flashcards

PLACENTAL HORMONES Flashcards

1
Q

primary site of hormone production

A

corpus luteum

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2
Q

Part of the reproductive system that is considered as steroid hormone producing

A

Placenta

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3
Q

Steroid hormones

A
  • Estrogen

- Progesterone

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4
Q

Hypothalamic-releasing hormones

A
  • GnRH
  • CRH
  • TRH
  • GHRH
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5
Q

Protein hormones

A 
􏰀 human placental lactogen
􏰀 chorionic gonadotropin
􏰀 АСТH
􏰀 chorionic thyrotropin
􏰀 parathyroid hormone-
related
􏰀 neuropeptide Y
􏰀 inhibin
􏰀 activin
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6
Q

also called “Pregnancy hormone”

A

HUMAN CHORIONIC GONADOTROPIN (HCG)

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7
Q

HCG like LH acts via

A

LH/hCG receptor

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8
Q

HCG is almost exclusively produced by

A

syncitiotrophoblast

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9
Q

_______ is also produced by fetal kidneys

A

B-hCG

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10
Q

HCG is also produced by

A

Neoplastic trophoblast

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11
Q

Detection of _____ in the urine is almost always indicative of pregnancy

A

hCG

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12
Q

HCG plasma half life

A

24 hours

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13
Q

LH plasma half life

A

2 hours

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14
Q

HCG is composed of 2 subunits

A

alpha (92 amino acids) and beta (145 amino acids)

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15
Q

subunit that is structurally related to LH, FSH, and TSH

A

A subunit

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16
Q

subunit of HCG is similar to LH

A

B subunit

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17
Q

subunit of FSH is similar to TSH

A

B subunit

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18
Q

codes for alpha subunits of all four glycoproteins

A

chromosome 6

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19
Q

codes for B-HCG and B- LH

A

chromosome 19

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20
Q

rate-limiting step in the formation of the complete

molecule

A

synthesis of the B- subunit

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21
Q

secrete both free a and B- subunits and the

complete molecule

A

trophoblast

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22
Q

HCG alpha and beta subunits are detectable in the plasma of pregnant women during

A

7-9 days after LH surge

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23
Q

hCG enters maternal blood at the time of

A

blastocyst implantation

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24
Q

maximum level of hCG is detected during

A

8-10 weeks

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25
Q

HCG begins to decline in maternal plasma during

A

10-12 weeks

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26
Q

HCG is considered nadir or in the lowest during

A

20 weeks

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27
Q

hCG plasma level parallels

A

urine level

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28
Q

amount of HCG by 6 weeks after LMP

A

1IU/ml

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29
Q

amount of HCG by 60th – 80th days after LMP

A

100 IU/ml

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30
Q

hCG in fetal plasma is ___ of the mother

A

3%

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31
Q

similar to maternal plasma but declines later in pregnancy

A

hCG in amniotic fluid

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32
Q

Levels of HCG is high during

A 
o multiple fetuses
o single erythroblastotic fetus
o H. mole
o chorioCA
o a fetus with Down syndrome
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33
Q

Levels of HCG is low during

A

o ectopic pregnancy

o spontaneous abortion

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34
Q

____ produced in cytotrophoblast, acts on syncitiotrophoblast to stimulate HCG secretion

A

GNRH

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35
Q

Other agents that regulate HCG synthesis

A
  • Inhibin
  • Interleukin 6
  • Epidermal growth factor
  • CAMP
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36
Q

Abnormal hCG levels is due to

A
  • D antigen isoimmunization

- Severe DM

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37
Q

Metabolic clearance of HCG per day

A

3ml/min or 4 liters of plasma/day

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38
Q

% Renal excretion of HCG

A

30%

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39
Q

% Metabolism of HCG in liver and kidneys

A

70%

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40
Q

Basis for pregnancy tests

A

Assay of HCG

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41
Q

Biologic functions of hCG

A
  1. Rescue and maintenance of corpus luteum in early pregnancy→ continued progesterone production
  2. Down-regulation of hCG /LH receptors in corpus luteum when trophoblasts produce sufficient progesterone for pregnancy maintenance
  3. Stimulates fetal testicular testosterone secretion and promote male sexual differentiation
  4. Stimulates the maternal thyroid via LH/hCG receptors and TSH receptors
  5. Promotes relaxin secretion by the corpus luteum
  6. Promote uterine vascular vasodilatation and
    myometrial smooth muscle relaxation
  7. Induces ovulation in the FSH primed ovaries of
    non- pregnant women
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42
Q

also known as:

chorionic growth hormone, chorionic somatomammotropin

A

Human Placental Lactogen (hPL)

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43
Q

Human Placental Lactogen (hPL) is structurally related to ______

A

Prolactin

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44
Q

Human Placental Lactogen (hPL) is produced by ________

A

Syncitiotrophoblast

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45
Q

Human Placental Lactogen (hPL) is produced also in conditions such as:

A
  • bronchogenic CA
  • hepatoma
  • lymphoma
  • pheochromocytoma
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46
Q

Human Placental Lactogen (hPL) ____ after fertilization will go to the placenta

A

5-10 days

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47
Q

At ________ hPL is already in the serum of pregnant woman

A

5th week of pregnancy

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48
Q

hPL rises until ______ proportional to placental mass

A

34th-36th week of pregnancy

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49
Q

______ is the amount of hPL late in pregnanacy

A

5-15 ug/L

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50
Q
  • secreted primarily into maternal circulation action is
    mainly on maternal
  • fail-safe mechanism to ensure nutrient
    supply to fetus in times of maternal starvation
A

hPL

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51
Q

Metabolic actions of hPL

A
  1. Lipolysis
    - increase circulatory FFA
    - provides source for maternal metabolism and fetal secretion
  2. Anti insulin action
    - increase maternal insulin favoring protein synthesis
    - ensures the metabolizable source of animo acid for transport to the fetus
52
Q

NOT required for a successful pregnancy outcome

A

hPL

53
Q

continually increasing in magnitude as pregnancy progresses, terminating abruptly after delivery of the fetus and placenta

A

Estrogen

that is why pregnancy is said to be a hyperestrogenic state

54
Q

Estrogen is produced exclusively by the _______

A

syncitiotrophoblast

55
Q

At ______ maternal ovaries produce small amounts of estrogen

A

2-4 weeks of pregnancy

56
Q

At ______ >50% of estrogen in the maternal circulation is produced in placenta

A

7th week of gestation

57
Q

In the _____
Acetate and Cholesterol
——–> Androstenedione

A

Theca cells

58
Q

In the _________

Androstenedione (Acted upon by Aromatase) ———-> Estrone (acted upon by 17B HSD) ———–> estradiol 17B

A

Granulosa cells

59
Q

Estrogen in the ______
Androstenedione ———> Estrone
Testosterone ————-> Estradiol 17B

A

Adipose tissue

60
Q

Precursors for estrogen synthesis :

A

o Maternal plasma dehydroepiandrosterone
sulfate (DHEAS)
o Liver: 16-hydroxydehydroepiandrosterone
o Fetal DHEAS

61
Q

Placenta is rich in

A

Sulfatase activity

62
Q

Sulfatase hydrolyzes _____

A

C19 steroid sulfate

63
Q

Immediate precursor for estrogen synthesis

A

C19 steroid sulfate

64
Q

Non-pregnant women, ratio of estradiol and estrone to estriol = ____

A

1

65
Q

During pregnancy (near term) ratio of estradiol and estrone to estriol increases to ____

A

10

66
Q

There is direct placental synthesis of estriol from ______

A

16 aOH C, steroids

67
Q

_____ source of 90% of precursor of placental estriol in near term normal human pregnancy

A

Fetus

68
Q

Largest organ of the fetus

A

Fetal adrenal gland

69
Q

daily production of steroid in fetal adrenal gland

A

100-200 mg/day

70
Q

daily production of steroid in adult adrenal gland

A

30-40 mg/day

71
Q

Early development of the fetal adrenal gland is under

A

Trophic influences

72
Q

Trophic influences such as:

A
  • fetal ACTH
  • Pit. PRL
  • growth factor from placenta
73
Q

fetal adrenal cortex grows rapidly, ____ larger than those of adults

A

25x

74
Q

_____ & _____ are produced by the placenta in minor fraction

A
  • Progesterone

- Pregnenolone

75
Q

_______ from de novo synthesis of acetate by the fetal adrenals - minor fraction

A

Cholesterol

76
Q

Hydrolysis of circulating ____ from the fetal circulation (major fraction)

A

LDL

77
Q

principal precursor for fetal steroidogenesis

A

Fetal plasma cholesterol

78
Q

Sources of fetal cholesterol:

A

o 20% - maternal transfer

o 80% - de novo synthesis by fetal liver

79
Q

_____ is low because of rapid use by fetal adrenals for steroidogenesis

A

Fetal plasma LDL

80
Q

Fetal-induced Modificationsof Estrogen Production

A
  1. Fetal death or ligation of the umbilical cord
  2. Fetal anencephaly
  3. fetal adrenal hypoplasia 4. Placental sulfatase deficiency
  4. Placental aromatase deficiency
  5. Down syndrome
  6. Depressed fetal adrenal use of LDL
81
Q

marked decrease in placental estrogens - precursor of placental estrogen is lost

A

Fetal death or ligation of the umbilical cord

82
Q

diminished availability of C-19 steroid precursors absence of adrenal cortex

A

Fetal anencephaly

83
Q

precludes the
hydrolysis of C19-steroid sulfates - step in estrogen
biosynthesis

A

Placental sulfatase deficiency

84
Q

cannot convert

dehydroepiandrosterone to estradiol

A

Placental aromatase deficiency

85
Q

low estriol- inadequate formation

of C19 steroids in adrenal glands

A

Down syndrome

86
Q

Causes hypertension

and severe DM

A

Depressed fetal adrenal use of LDL

87
Q

Maternal Conditions that Affect Placental Estrogen Formation:

A
  1. Glucocorticosteroid treatment
  2. Adrenal dysfunctions
  3. Ovarian androgen-producing tumor
  4. Renal disease
  5. Hypertensive disorder and diabetes
  6. Neoplastic trophoblastic disease
88
Q

inhibit ACTH secretion - decreased maternal and fetal secretion of fetal estrogen production

A

Glucocorticosteroid treatment

89
Q

decreased estrone and estradiol

A

Adrenal dysfunctions

90
Q

fetus is not virilized because androgens passing through placenta is efficiently converted to estradiol

A

Ovarian androgen-producing tumor

91
Q

lower estriol levels in urine of pregnant women because of decreased renal clearance

A

Renal disease

92
Q

decreased estrogen formation due to decrease in uteroplacental blood flow

A

Hypertensive disorder and diabetes

93
Q

low estrogen because no fetal adrenal source of C19-steroids

A

Neoplastic trophoblastic disease

94
Q

Estriol - Assess Fetal Status

A
  1. Measurement of urinary or plasma estriol has no clinical use in high-risk pregnancy management
  2. Part of triple screening - Down syndrome together with AFP and HCG
95
Q

After _____ very little progesterone produced by ovaries

A

6-8th weeks

96
Q

At ____ will not reduce levels of urinary pregnanediol or estrogens even if bilateral oophorectomy or surgical removal of corpus luteum is done

A

7-10th week

97
Q

Biosynthesis of Progesterone is is the responsibility of

A

Syncitiotrophoblast

98
Q

production rate in late, single, normal pregnancies

A

250

mg/day

99
Q

production rate in multiple fetuses

A

> 600 mg/day

100
Q

Principal precursor of Progesterone by 90%

A

Maternal plasma LDL cholesterol

101
Q

In the _______

Cholesterol (acted by Cytochrome P450) ———-> Pregnenolone

A

Mitochondria

102
Q

In the _______

Pregnenolone (acted by HMG CoA Reductase) ——–> Progesterone

A

Microsome

103
Q

_____ preferably uses LDL cholesterol for progesterone biosynthesis

A

Trophoblast

104
Q

rate of progesterone biosynthesis is dependent on

A

number of LDL

105
Q

__ placental progesterone enters maternal plasma

A

80%

106
Q

Is there a relationship between fetal well-being and progesterone

A

None

107
Q

Receptor for progesterone synthesis is first seen in _____

A

4 weeks post- conception

108
Q

Derived from propiomelanocortin (POMC)

A

Chorionic Adreno Corticotropin Hormone (ACTH)

109
Q

POMC – precursor for:

A

o АСТH
o Melanocyte-stimulating hormone
o Enkephalins
o a, ß and gamma endorphins

110
Q

secreted into the mother or fetus

but ACTH does not cross the placenta (fr mom to fetus)

A

placental ACTH

111
Q

􏰀 produced by placenta

􏰀 no significant biological role

A

Chorionic Thyrotropin

112
Q

􏰀 demonstrated in adult tissues - uterus, corpus luteum, mammary tissue
􏰀 fetal tissues - parathyroid, kidney and placenta
􏰀 serves as parathormone of the fetus - active transport
of calcium across trophoblast from mother to fetus

A

Parathyroid Hormone related Protein (PTHTP)

113
Q

􏰀 widely distributed in brain
􏰀 found in the periphery → sympathetic neurons
innervating the CVS, respiratory, GIT and GUT
systems
􏰀 isolated in placenta, localized in cytotrophoblast

A

Neuropeptide-Y (NPY)

114
Q

high concenration of potassium

A

increase release of

NPY from trophoblast

115
Q

treatment of placental cell with NPY

A

release of CRH

116
Q

acts to inhibit FSH release by the pituitary precludes ovulation during pregnancy

A

Inhibin

117
Q

hormone that is greater during labor

A

Activin

118
Q

acts as hCG-releasing hormone

A

Gonadotrophin releasing hormone (GNRH)

119
Q

indicative of a hierarchy of control of the synthesis of chorionic trophic agents

A

Presence of Hypothalamic-like releasing hormones

120
Q

act in a paracrine

manner to regulate GNRH synthesis

A
  1. Inhibin

2. Activin

121
Q

synthesized by trophoblasts, amnion, chorion and decidua

A

Corticotropin Releasing Hormone (CRH)

122
Q

Amount of CRH in non-pregnant woman

A

15 pg/ml

123
Q

Amount of CRH in early 3rd trimester

A

250 pg/ml

124
Q

Amount of CRH in Term

A

1-2 ng/ml

125
Q

CRH is also found in _______

A

Umbilical venous blood

126
Q

CRH is increased in:

A

o preterm labor
o fetal asphyxia
o twin pregnancy - 4x

127
Q

Biologic roles of CRH

A

o smooth muscle relaxation
o induction of myometrial contractions -
induces prostaglandin formation

PYSIO OB (5 decks)

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