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*GIGU I > 42. Physiology of Pregnancy, Parturition, and Lactation > Flashcards

42. Physiology of Pregnancy, Parturition, and Lactation Flashcards

1
Q

What is the maternal side of the placenta, that is immediately apposed to the chorion frondosum, or fetal side of mature placenta?

A

Decidua basalis

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2
Q

3 major structures that make up the mature placenta

A

Chorionic villi
Intervillous space
Decidua basalis

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3
Q

Main functions of the placenta

A

Fetal “gut” supplying nutrients

Fetal “lung” exchanging O2 and CO2

Fetal “kidney” regulating fluid volume and disposing of waste

Endocrin gland synthesizing steroids and proteins that affect maternal and fetal metabolism

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4
Q

Endocrine functions of placenta

A

Maintaining pregnant state of uterus

Stimulating lobuloalveolar growth and function of maternal breasts

Adapting aspects of maternal metabolism and phys to support fetus

Regulating aspects of fetal dev’t

Regulating timing and progression of parturition

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5
Q

______ represent the functional unit of the placenta

A

Chorionic villi

[extensive branching and increased surface area for exchange]

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6
Q

_____ arteries from the maternal side of the placenta empty into the ______ space, which is drained by maternal veins

A

Spiral; intervillous

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7
Q

Describe maternal blood flow to fetus in terms of arterial and venous supply, as well as purpose of intervillous spaces

A

Arterial blood discharged from ~120 spiral aa., spurts into intervillous space

Filling of these spaces dissipates the force and reduces blood velocity

Slowing of blood flow allows adequate time for exchange of nutrients

Blood drains through venous orifices and enters placental veins (no capillaries are present!)

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8
Q

Principal factors regulating maternal blood flow

A

Geometry of blood vessels — spiral arteries are perpendicular and veins are parallel

Differences between maternal vs. fetal arterial and venous pressure

Patterns of uterine contractions — attenuate arterial inflow and interrupt venous drainage

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9
Q

Fetal blood flow originates from two umbilical arteries which carry ______ blood. These arteries branch and penetrate the ______ to form a chorionic villi capillary network, obtaining oxygen and nutrients and returning them to the fetus from a single umbilical vein

A

Deoxygenated; chorionic plate

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10
Q

Terminal dilations in the fetal capillary network offer _____ blood flow and thus improved exchange of nutrients

A

Slower

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11
Q

Describe pO2, pCO2, and pH of maternal blood entering the intervillous space

A

pO2 ~100 mm Hg

pCO2 ~40 mm Hg

pH of 7.4

[fetal pO2 is 23 umbilical aa., 30 in umbilical v.]

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12
Q

Diffusion of O2 into the chorionic villi causes the pO2 of blood in intervillous space to fall to 30-35 mm Hg and lower in umbilical v. of the fetus. What allows sufficient oxygen saturation in fetus?

A

Differences in hemoglobin structure make it higher affinity for O2, allowing sufficient Hb saturation

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13
Q

What drives CO2 transfer between mother and fetus?

A

Concentration gradient difference

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14
Q

Compare pCO2 in umbilical aa. vs. intervillous spaces near term

A

pCO2 ~48 mm Hg in umbilical aa.

pCO2 ~43 mm Hg in intervillous spaces

[concentration gradient driving CO2 to maternal side]

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15
Q

Describe affinity for CO2 in maternal vs. fetal blood

A

Fetal blood has slightly lower affinity for CO2 than maternal blood

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16
Q

T/F: all factors favor transfer of CO2 from fetus to mother

A

True

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17
Q

Other than concentration gradient-based passive diffusion, what are some other solute transfer mechanisms between mother and fetus?

A

Passive exchange (non-protein nitrogen wastes like urea/creatinine, lipid soluble hormones)

Facilitated diffusion (glucose to fetus)

Primary and secondary active transport to fetus to support growth (amino acids, vitamins, minerals)

Receptor mediate endocytosis (large molecule exchange like LDL, hormones, Abs)

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18
Q

2 important functions of amniotic fluid

A

Mechanical buffer

Fetus excretes waste products through it

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19
Q

How often does water in amniotic fluid “turn over”?

A

At least 1x/day

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20
Q

At >10-12 weeks, what provides 75% of amniotic fluid production?

A

Kidney excretions of fetus

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21
Q

Kidney excretions provide ~75% of amniotic fluid production, what provides the rest?

A

Pulmonary secretions

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22
Q

Fluid removal from fetus:

55% from ______

30% from ______

15% from _____

A

GI tract

Amnion

Lungs

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23
Q

The placenta plays a key role in manufacture of what biologic molecules?

A

Steroid hormones

Amines

Polypeptides (hormones and neuropeptides)

Proteins/glycoproteins

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24
Q

The placenta regulates release of local placental hormones as well as hormones into fetal or maternal circulation in _______ fashion

A

Paracrine

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25
Q

What cell type secretes hCG

A

Syncytiotrophoblasts

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26
Q

What is the significance of hCG being structurally related to LH?

A

It can bind LH receptors with high affinity

It rapidly accumulates in maternal circulation

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27
Q

How do levels of hCG change during pregnancy?

A

Serum levels double daily up to ~10 weeks (that’s when they are highest), then sharp followed by gradual decline

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28
Q

Primary function of hCG

A

Stimulates LH receptors in corpus luteum, preventing luteolysis

Maintains high levels of luteal derived progesterone

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29
Q

What hormone is thought to be responsible for nausea associated with morning sickness?

A

hCG

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30
Q

Small amounts of hCG enter male fetal circulation with what purpose?

A

Stimulate fetal Leydig cells to produce testosterone

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31
Q

What is the primary human chorionic somatomammotropin (hCS)?

A

Human placental lactogen (hPL)

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32
Q

What 2 hormones is hPL structurally related to?

A

Growth hormone and prolactin

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33
Q

What cells produce hPL?

A

Syncytiotrophoblast

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34
Q

When is hPL detected in syncytiotrophoblasts vs. in maternal serum?

A

Detected at day 10 in syncytiotrophoblasts and in maternal serum at 3 weeks

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35
Q

Functions of hPL

A

Coordinating metabolism of fetoplacental unit via conversion of glucose to fatty acids and ketones; can have antagonistic action to maternal insulin, contributing to GDM

Lipolytic actions help mother shift to free-fatty acid use for energy

Promotes development of maternal mammary glands during pregnancy

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36
Q

High levels of _____ are required throughout pregnancy for implantation and early maintenance of pregnancy

A

Progesterone

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37
Q

Where is progesterone derived from in pregnancy?

A

Corpus luteum

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38
Q

Primary functions of progesterone in pregnancy

A

Increased adhesion proteins in endometrium

Stimulates endometrial gland secretions for early nutrient transfer

Reduces uterine motility

Inhibits propagation of uterine contractions

Induces mammary growth and differentiation

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39
Q

What hormone is responsible for inducing endometrial growth, progesterone receptor expression, and LH surge just prior to ovulation?

A

Estrogen

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40
Q

Functions of estrogen:

Increases _____ blood flow

Increases _____ receptor expression in syncytiotrophoblasts

Induces _____ and ______ receptors necessary for parturition

Increases growth and development of ______ glands

A

Uteroplacental

LDL

Prostaglandins; oxytocin

Mammary

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41
Q

How do levels of hPL change throughout pregnancy

A

Gradual rise until parturition

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42
Q

How do levels of progesterone change throughout pregnancy

A

Gradual rise until parturition

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43
Q

How do levels of estrogen change throughout pregnancy

A

Gradual rise until parturition

Estradiol levels are highest, estriol exceeds estrone starting at around 30 weeks

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44
Q

T/F: during pregnancy, maternal levels of progesterones and estrogens decline to levels substantially lower than during a normal menstrual cycle

A

False; they are much higher than normal menstrual cycle

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45
Q

The placenta is an imperfect organ and cannot produce estrogens and progesterone along, so coordination between maternal, placental, and fetal tissues are required. The mother is responsible for supplying _____ for hormone production; the fetal _____ and ______ supply enzymes that the placenta lacks

A

Cholesterol; adrenal gland; liver

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46
Q

What enzymes for estrogen production are provided by the placenta?

A

3B-hydroxysteroid dehydrogenase

Aromatase

Sulfatase

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47
Q

What enzymes are provided by the fetus for estrogen production?

A

17a-hydroxylase
17,20-desmolase
16a-hydroxylase

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48
Q

A luteal-placental shift occurs around week ____ in terms of progesterone production. Its production is largely unregulated. Syncytiotrophoblasts import ____ from maternal blood; they express CYP11A1 and 3B-HSD1

Progesterone is released primarily into ______ compartment, thus maternal serum levels _____ throughout pregnancy

A

8; cholesterol

Maternal; rise

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49
Q

T/F: the placenta produces cholesterol

A

False, it cannot produce cholesterol

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50
Q

The placenta lacks 17a-hydroxylase and 17,20 desmolase needed for estrone and estradiol, as well as 16a-hydroxylase needed for estriol. What overcomes this?

A

The maternal-placental-fetal unit —

Mother supplies cholesterol

Fetal adrenal gland and liver supply enzymes needed, also produce DHEAS and 16a-OH-DHEAS (weak androgens)

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51
Q

T/F: the fetus avoids high levels of steroid hormones

A

True — the fetus lacks 3B-hydroxysteroid dehydrogenase and aromatase, thus no estrogen production

Fetus conjugates steroid intermediates to sulfate, reducing their activity

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52
Q

What organ completes the steroidogenesis of estrogens?

A

Placenta

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53
Q

The fetus conjugates steroid intermediates to sulfate, reducing their activity. So in the production of estrogen, _______ travels from the placenta to fetus. DHEA and 16a-hydroxyl-DHEA are _____while in fetus. As the DHEA and 16a-hydroxyl-DHEA-S move into the placenta, a ______ removes the sulfate groups. The placenta then completes steroidogenesis of estrogens

A

Pregnenolone; sulfated; sulfatase

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54
Q

Mean duration of human pregnancy

A

~266 days (38 weeks) from ovulation

Or ~280 days (40 weeks) from day 1 menstrual cycle

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55
Q

How does maternal blood volume change in response to pregnancy?

A

Blood volume increases

Total plasma volume increases 40-50%

Begins to increase in 1st trimester, rapid increase in 2nd and 3rd trimester

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56
Q

What system mediates the increase in maternal blood volume in response to pregnancy?

A

Renin-angiotensin-aldosterone system (augments renal reabsorption of salt and water)

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57
Q

How do maternal RBCs change in response to pregnancy? How does this affect hematocrit

A

RBC increase of 20-30%, mediated by increases in erythropoitin

Net result is a decrease in hematocrit

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58
Q

How does maternal cardiac output change in response to pregnancy?

A

Increased blood volume results in increase in heart rate (~15 bpm)

CO increases appreciably in 1st trimester, with slight increase at 2nd and 3rd trimester (overall 45% increase)

Increase in CO reflects mainly an increase in stroke volume but also heart rate

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59
Q

How does maternal mean arterial pressure change in response to pregnancy? Why?

A

Despite increase in plasma volume, MAP decreases mid-pregnancy with a rise during 3rd trimester (but still remaining lower than normal)

This is due to decrease in peripheral vascular resistance because of vasodilating effects of progesterone and estrogen

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60
Q

How does the increasing progesterone during pregnancy affect alveolar ventilation in the mother?

A

Increases it

Overall little effect on respiratory rate

Tidal volume increases markedly — 40% (decreases CO2 levels in maternal blood)

As fetus grows in late pregnancy, displacement of diaphragm can occur so lung expansion decreases

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61
Q

Maternal tidal volume markedly increases in pregnancy, thus decreasing CO2 levels in maternal blood. What condition can this lead to, and how is it compensated?

A

Mild respiratory alkalosis can occur; compensated for by kidney lowering plasma bicarb

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62
Q

In the maternal response to pregnancy there is an increased demand for what 3 dietary nutrients in particular?

A

Protein — need additional 30g/day for growth

Iron — need net gain of 800 mg circulating iron for expanding Hb mass (nonpregnant woman absorbs 1.5mg/day, pregnant woman requires 7mg/day)

Folate — increase in blood cells

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63
Q

A deficiency in folate in pregnancy leads to what type of birth defects?

A

Neural tube defects

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64
Q

Maternal GI tract changes in pregnancy

A

Morning sickness (usually resolves by 20 weeks when hCG decreases)

Mechanical changes — stomach displacement, changes in esophageal sphincter tone can lead to acid reflux

Decreased colonic motility — increased water absorption; constipation

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65
Q

What happens to maternal insulin in early pregnancy?

A

Increased secretion and sensitivity

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66
Q

What happens to maternal insulin response in the 2nd and 3rd trimester? Why?

A

Maternal insulin resistance develops

Shunts glucose to fetus; due to hPL, hGH, progesterone, cortisol, and prolactin

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67
Q

If insulin resistance in mother is too high, GDM can develop, resulting in increased maternal BG, as well as what changes in fetus?

A

Increased fetal glucose uptake and BG —> increased growth of fetus, chemical and cellular imbalances after birth - hypoglycemia, jaundice, polycythemia, and hypocalcemia

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68
Q

Human birth usually occurs at _____ weeks gestation, which is ______ weeks fetal age

A

~40; 38

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69
Q

Parturition involves:

transformation of the myometrium from quiescent to highly ______

Remodeling of the uterine _____ such that it softens and dilates

Rupture of fetal ______

Expulsion of uterine contents and return of uterus to prepregnant state

A

Contractile

Cervix

Membranes

70
Q

What is the obstetric definition of labor?

A

Series of regular, rhythmic, and forceful contractions that develop to facilitate thinning and dilation of the cervix — these may last for several hours, a day, or even longer and eventually result in expulsion of fetus, membranes, and placenta

71
Q

Once labor is initiated, it is sustained by a series of ____ feedback mechanisms

A

Positive

72
Q

Parturition occurs in distinct stages 0-3. What is associated with stage 0?

A

Uterine tranquility and refractoriness to contraction

73
Q

Parturition occurs in distinct stages 0-3. What is associated with stage 1?

A

Uterine awakening, initiation of parturition, extending to complete cervical dilatation

74
Q

Parturition occurs in distinct stages 0-3. What is associated with stage 2?

A

Active labor, from complete cervical dilatation to delivery of newborn

75
Q

Parturition occurs in distinct stages 0-3. What is associated with stage 3?

A

From delivery of fetus to expulsion of the placenta and final uterine contraction

76
Q

Stage 1 of parturition involves uterine awakening, initiation of parturition, extending to complete cervical dilatation. What physiological changes are associated with this stage?

A

Increase in number of gap junctions between myometrial cells; increase in number of oxytocin receptors

77
Q

During stage 0 of parturition, which constitutes most of pregnancy, the uterus is relaxed and relatively insensitive to hormones that stimulate contractions such as ___ and _____

A

Prostaglandins; oxytocin

78
Q

During stage 0 of parturition, uterine myometrial cells undergo significant _________

Weak, irregular contractions known as ____ ____ contractions occur towards the end of pregnancy; these are not powerful enough to induce labor and are thought to prepare the uterus for parturition

A

Hypertrophy

Braxton hicks

79
Q

What happens to uterine excitability towards the end of pregnancy?

A

Increases; will develop strong rhythmical contractions to expel conceptus

This is due to progressive hormone and mechanical changes

80
Q

Prior to labor, the myometrium transforms to a more contractile state. What stage of parturition is this associated with?

A

Stage 1 = transformation/activation

81
Q

Stage 1 of parturition involves production of contraction-associated hormones and proteins. What are some examples of these?

A

Prostaglandin F2a receptors

Oxytocin receptors

Enzymes involved in prostaglandin synthesis

Enzymes that breakdown collagen matrix in cervix

Components of gap junctional complexes

82
Q

During stage 1 of parturition, components of gap junctional complexes increase; why are these especially important?

A

Because they form electrochemical connections between myometrium cells to synchronize the contractions

83
Q

Induction of active labor occurs in stage 2 of parturition. What are the 3 major factors that induce contractions?

A

Increased levels of prostaglandins (especially PGF2a)

Increased myometrial interconnectivity

Increased myometrial responsiveness to prostaglandins and ocytocin

84
Q

Contractions that begin in stage 2 force the fetal head against the _____, which becomes progressively compliant as the ________ remodels.

Eventually enough dilation occurs to allow fetus through

A

Cervix; ECM

85
Q

Reciprocal changes in uterine progesterone and estrogen receptors are necessary for onset of labor. Progesterone typically promotes myometrial ______ during pregnancy, and _____ contractions of labor

A

Relaxation; blocks

86
Q

Nuclear _______ antagonists are drugs that increase myometrial contractility/excitability and can induce labor at any stage of pregnancy

A

Progesterone

87
Q

At the onset of labor, there is a desensitization of uterine cells to the actions of progesterone. This leads to an increase in _____ receptor expression, thus augmenting myometrial contractility and thus cervical dilation

A

Estrogen

88
Q

Estrogens oppose the action of progesterone by increasing responsiveness to ____ and _____, stimulating formation of gap junctions and increasing numbers of oxytocin receptors in myometrium and _____ tissue

There is also an increase in production/release of prostaglandins by fetal _____

A

Oxytocin; prostaglandins; decidual

Membranes

89
Q

Actions of prostaglandins in labor

A

Strongly stimulate myometrial contraction; believed to initiate labor

90
Q

Large doses of what 2 prostaglandins evokes myometrial contractions at any stage of gestation?

A

PGF2a

PGE2

91
Q

PGF2a potentiates ______-induced contractions by promoting formation of gap junctions

A

Oxytocin

92
Q

Prostaglandins stimulate the ______ of the cervix in early labor. Their metabolic products increase in blood and ______ just before and during labor

A

Effacement

Amniotic fluid

93
Q

Prostaglandin synthesis is stimulated by what 3 factors?

A

Estrogen in fetal membranes

Oxytocin in uterine cells

Uterine stretch

94
Q

The uterus is insensitive to oxytocin until ____ weeks

A

20

95
Q

What hormone increases oxytocin receptors?

A

Estrogen

96
Q

Estrogen increases oxytocin receptors in _____ _____ for smooth muscle contraction, as well as receptors in ____ ____ to stimulate PGF2a production

A

Uterine myometrium; decidual tissue

97
Q

T/F: Oxytocin receptors increase to 80x higher than baseline by 36 weeks, and increase to 200x by early labor

A

True

98
Q

What hormone is released in bursts during active labor

A

Oxytocin

[frequency increases as labor progresses]

99
Q

What is the primary stimulus for oxytocin release?

A

Distention of cervix

100
Q

The primary stimulus for oxytocin release is distention of the cervix, this is known as the ______ reflex — a ______ feedback loop to enhance labor

A

Ferguson; positive

101
Q

_______ = cytokine structurally related to insulin, produced by the corpus luteum, placenta, and decidua thought to play a role in keeping the uterus in a quiet state during pregnancy

A

Relaxin

102
Q

During what weeks of pregnancy would you expect maximal plasma concentrations of relaxin? Why?

A

38-42

May soften and help dilate cervix; elevated levels at 30 weeks are associated with premature birth

103
Q

Describe uterine size as a factor in the mechanical changes regulating parturition

A

Stretch of smooth muscle of uterus increases the Ferguson reflex positive feedback —> further contractions

Uterine stretch also increases prostaglandin production

[twins average 19 day shorter gestation due in part to the increased stretch leading to the above factors]

104
Q

The signals for initiation of labor are not completely understood. The placenta produces _______, and maternal levels of this rise during late pregnancy and labor, promoting myometrial contractions and sensitizing the uterus to prostaglandins and oxytocin

A

CRH

105
Q

CRH accumulates in fetal circulation and stimulates fetal ______ secretion

A

ACTH

106
Q

CRH accumulates in fetal circulation and stimulates fetal ACTH secretion.

This increases fetal production of ______ ______ which stimulates further placental CRH release

It also increases fetal production of _______ _______, which enhances myometrial contractility

A

Adrenal cortisol

Fetoplacental estrogen

107
Q

Throughout most of pregnancy, the uterus undergoes periodic episodes of weak and slow contractions = braxton hicks contractions.

These become exceptionally strong during the last hours of pregnancy into active labor. Describe the actions of uterine contractions

A

Begin to stretch the cervix, shorten muscle cells

Retract lower uterine segment and cervix upward

Cervix becomes increasingly dilated and is drawn up to just below the pelvic inlet

108
Q

Describe the postive feedback involved in maintaing labor

A

Positive feedback loops involving prostaglandins from uterine wall, oxytocin from posterior pituitary, and uterine contractions themselves sustain labor once it has started

Uterine contractions stimulate prostaglandin release, which increases the intensity of uterine contractions

Uterine activity stretches the cervix which stimulates oxytocin release through ferguson reflex

109
Q

During parturition, the fully dilated cervix is drawn up just below the ________. Subsequent uterine contractions push the fetus downward and through the pelvis

The entire process varies in duration, but the ______ stage occupies most of the time. The _____ stage generally lasts less than 1 hr

A

Pelvic inlet

First; second

110
Q

_____ ____ = refers to where the presenting part of the fetus is in the pelvis relative to ischial spines

A

Fetal station

111
Q

The fetal station is usually based on the baby’s _______, and is measured from -3 to +3

A

Head

112
Q

When the fetal station = 0 station, the presenting part is even with the ___ ____

A

Ischial spines

[baby is said to be “engaged” when largest part of head enters pelvis]

113
Q

If the presenting part of the fetus lies above the ischial spines, the station is reported as a ____ number

A

Negative

114
Q

Phases of fetal delivery

A

Dilation and effacement

Descent and expulsion

Expulsion of placenta

115
Q

______ is the process by which the cervix prepares for delivery, measured in percentages: at 50% the patient is halfway, 100% the cervix is paper thin and labor is right around the corner

A

Effacement

116
Q

Describe dilation of cervix, direction of contractions, and average duration of descent and expulsion phase of delivery

A

Cervix fully dilated to 10 cm

Contractions are strongest at top pushing fetus downward

Avg 20-50 min duration

117
Q

Describe expulsion of placenta

A

Uterus contracts, reducing area of attachment

Separation of placenta results in bleeding and clotting. Oxytocin constricts uterine blood vessels. Nipple stimulation induces oxytocin release. Synthetic oxytocin is sometimes given to assist in uterine contractions

118
Q

One complication of labor/delivery is prolonged labor — which is defined as labor lasting more than ____-____ hrs.

Multiple types are distinguished based upon what 2 factors?

A

18-24

  • based upon which stage of labor is prolonged (latent phase, cervical dilation per hour, prolonged deceleration, secondary arrest of dilation, protracted descent, arrest of descent, prolonged second stage)
  • time variability in nulliparous vs. multiparous women
119
Q

Prolonged labor can be characterized based on whether the mother is multiparous or nulliparous. Which one requires less time for diagnosis of prolonged labor?

A

Multiparous — labor is expected to proceed slightly more quickly

120
Q

Main causes of prolonged labor

A

Poor uterine contractions
Baby’s position or size is abnormal
Issues with pelvis or birth canal

121
Q

Obstructed labor is also known as labor ____

A

Dystocia

122
Q

Describe labor dystocia

A

Even though uterus is contracting normally, the baby does not exit the pelvis during childbirth due to being physically blocked

123
Q

Common causes of labor dystocia

A

Breech presentation

Macrosomia (baby is too large)

Occiput posterior (fetus face-up)

Malpresentation - fetal head is not perfectly flexed

Compound presentation - 2 parts presenting

Congenital abnormalities obstructed in birth canal

124
Q

Variations in breech presentation

A

Complete breech

Incomplete (footling - buttocks first with one leg extended)

Frank breech (legs extended, buttocks first)

125
Q

Possible causes for breech presentation

A

Large baby
No fluid
Birth defects
Uterine anomalies

126
Q

Risks of labor from breech presentations

A

Fetal injury
Cord prolapse
Cord entrapment
Maternal injury

127
Q

Delivery options for breech presentation

A

Vaginal breech delivery

External cephalic version (ECV)

Elective C-section

128
Q

One possible complication of labor/delivery is ruptured uterus in which integrity of myometrial wall is breached. This can be spontaneous or traumatic in nature and typically occurs in active labor, but can occur during late pregnancy.

What are risk factors/causes of ruptured uterus?

A

Uterine scar from previous C-section, dysfunctional/prolonged labor, labor augmentation by oxytocin or prostaglandins, excessive manual pressure applied to fundus during delivery

129
Q

Signs/symptoms of ruptured uterus

A

Abdominal pain and vaginal bleeding

Deterioration of fetal HR (leading sign)

Loss of fetal station on manual vaginal exam (cardinal sign)

Intra-abdominal bleeding leading to hypovolemic shock

130
Q

Preterm labor is defined as labor beginning before the ____ week of pregnancy

A

37th

[this occurs in 12% of all pregnancies; uterine contractions cause the cervix to open earlier than normal]

131
Q

Possible medical risk factors for preterm labor

A

UTIs

Uterine or cervical abnormalities

Chronic illness (HTN, kidney disease, diabetes, etc.)

Lifestyle risk factors: smoking, drinking alcohol, drug abuse, high levels of stress, etc.

132
Q

Condition characterized by high blood pressure and signs of damage to another organ system during pregnancy, often the kidneys

A

Preeclampsia

133
Q

Preeclampsia occurs after week ____ of pregnancy and affects at least 5-8% of pregnancies.

A

20

134
Q

Other than high blood pressure, what other symptoms typically accompany preeclampsia?

A

Proteinuria

Generalized edema

135
Q

Causes of preeclampsia

A

No definitive known cause!

Likely multifactorial: abnormal placentation, immunologic factors, prior maternal pathology like HTN, obesity, and hx of preeclampsia

136
Q

Disease of the placenta is thought to be involved in preeclampsia — thought to be associated with limited blood supply to ______ aa., causing ischemia and endothelial damage with release of cytokines

A

Uterine

137
Q

T/F: The placenta of women with preeclampsia is abnormal and characterized by poor trophoblastic invasion

A

True

138
Q

If preeclampsia is left untreated, it can lead to serious or fatal complications for both the mother and baby —> eclampsia. What signs/symptoms are associated with eclampsia?

A

HELLP:

Hemolysis
Elevated Liver enzymes
Low Platelet count

139
Q

Mechanism thought to be responsible for preeclampsia

A

Deficient trophoblast invasion of spiral aa. —> decreased placental blood flow —> placental ischemia —> placental release of factors leading to endothelial activation/dysfunction —> decreased renal pressure natriuresis and increased TPR —> HTN

140
Q

The mammary gland consists of 15-20 lobes, composed of glandular tissue, as well as fibrous and _____ tissue.

Each lobe is made up of what components?

A

Adipose

Alveoli, blood vessels, lactiferous ducts

141
Q

Describe the alveolar walls associated with mammary glands for lactation

A

Single layer of cuboidal to columnar epithelial cells — depending on fullness of alveolar lumen

142
Q

The luminal epithelium associated with mammary glands is called _____ epithelium; these cells are responsible for milk synthesis and production

This epithelium is surrounded by _______ cells, which exist between the epithelial cells and basement membrane. They have contractile function and move milk from alveoli into ducts

A

Alveolar

Myoepithelial

143
Q

When fully developed, the the lobules of the mammary glands consist of rounded ______, which open into the smallest branches of milk-collecting ducts. These, in turn, unite to form larger _______ ducts, each draining a lobe of the gland. The lactiferous ducts converge towards the _____ of the nipple (or papilla) beneath which they form dilations, or _______ ______, that serve as small reservoirs for milk.

After narrowing in diameter, each lactiferous sinus runs separately through the nipple to open directly on its surface. Also opening onto the peripheral area of the areola are small ducts from the ______ glands, which are large sebaceous glands whose secretions probably have a lubricative function during suckling

A

Alveoli; lactiferous; areola; lactiferous sinuses

Montgomery

144
Q

The breast consists of a series of secretory lobules which empty into ductules. Ductules form from 15-20 lobules which combine into a duct, which widens at the ______

The lactiferous duct carries secretions to outside

A

Ampulla

145
Q

Describe mammary glands at birth. How does this change leading up to puberty?

A

Almost entirely composd of lactiferous ducts with few alveoli

Apart from some branch development, the breast remains in this state until puberty.

Under the actions of estrogens, lactiferous ducts sprout and branch — ends form small, solid, spheroidal masses of cells which develop into alveoli

146
Q

As the menstrual cycle is established, mammary tissue is exposed to ____ and ______ which induces additional ductal-lobular-alveolar growth

A

Estrogen; progesterone

147
Q

During puberty, breasts increase in size due to increased deposition of ___ and ____ tissue

A

Adipose; connective

148
Q

What are the cyclical changes to breasts that occur with puberty and establishment of menstrual cycle?

A

Increase in breast volume
Breast tenderness
Some secretory activity may occur
Involution

149
Q

Breast development at puberty depends primarily on estrogens and progesterone.

During pregnancy, gradual increases in ____ and ____, and very high levels of estrogen and progesterone lead to full development of breasts

A

PRL; hPL

150
Q

______ hormones promote proliferation of alveolar and duct cells

________ hormones promote initiation of milk production by alveolar cells

A

Mammogenic

Lactogenic

151
Q

_______ hormones promote contraction of myoepithelial cells, and thus milk ejection

_______ hormones maintain milk production after it has been established

A

Galactokinetic

Galactopoietic

152
Q

Examples of mammogenic hormones (promote cell proliferation)

A

Lobuloalveolar growth: estrogen, growth hormone, cortisol, prolactin

Ductal growth: estrogen, growth hormone, cortisol, relaxin

153
Q

Examples of lactogenic hormones

A 
Prolactin
hCS (or hPL)
Cortisol
Insulin
Thyroid hormones
Withdrawal of estrogen+progesterone
154
Q

Galactokinetic hormones

A

Oxytocin

Vasopressin

155
Q

Galactopoietic hormones

A

Prolactin (primary)

Cortisol and other metabolic homrones (permissive)

156
Q

By midpregnancy, duct and lobule proliferation is complete and differentiation of alveolar cells occurs.

Lactogenesis is inhibited by ____ and _____ which render mammary cells unresponsive to prolactin

Small amounts of _____ are produced in late pregnancy, which is a thin, yellowish milk secreted the first few days after parturition containing a high concentration of immunoglobulins

A

Estrogen; progesterone

Colostrum

157
Q

Following parturition, there is a drop is steroid hormones. In the absence of suckling, how long will milk secretion last?

A

3-4 weeks

158
Q

Following parturition, suckling stimulates prolactin secretion via a neuroendocrine reflex. The amount released depends on duration and strength of suckling.

Suckling inhibits hypothalamic ____ neurons

A

Dopaminergic

159
Q

Classic lactogenic hormone structurally related to GH, having mammogenic, lactogenic, and galactopoietic effects

A

Prolactin

160
Q

Feedback from prolactin decreases dopamine release, as well as ____ release, which results in decreases in LH and FSH

What does this mean for resuming menstrual cycles after parturition?

A

GnRH

High levels of prolactin may lead to lactational amenorrhea

161
Q

____enhances milk ejection by stimulating contraction of network of myoepithelial cells surrounding alveoli and ducts of breast (thus it has galactogenic effect)

A

Oxytocin

162
Q

Alveolar epithelial cells secrete milk components by what 5 main pathways?

A
  1. Secretory pathway
  2. Transcellular endocytosis and exocytosis
  3. Lipid pathway
  4. Transcellular salt and water transport through channels+transporters
  5. Paracellular pathway for ions and water
163
Q

Describe secretory pathway for milk production

A

Lactalbumin and casein synthesized in ER

Ca and phosphate added to lumen of golgi

Lactose synthetase in lumen of golgi catalyzes lactose synthesis

Water enters secretory vesicles by osmosis

164
Q

Describe transcellular endocytosis and exocytosis pathway for milk production

A

Maternal immunoglobulins (primarily IgA) taken up by endocytosis through basolateral membrane

Then transported to apical membrane and secreted via exocytosis

165
Q

Describe lipid pathway for milk production

A

Fats that are predominant in milk (FA chains >16 carbons) originate from diet or fat stores in surrounding adipose

FAs form lipid droplets which move to apical membrane

As the apical membrane surrounds the droplets and pinch off, milk lipids are secreted to lumen in membrane bound vesicles

166
Q

Describe transcellular salt and water transport mechanism of milk production

A

Various transport processes at apical and basolateral membranes move small electrolytes from interstitial fluid into alveolar lumen

Water follows an osmotic gradient generated primarily by lactose and some from electrolytes

167
Q

Paracellular pathway for milk production

A

Salt and water can also move into lumen of alveolus through tight junctions

Cells, primarily leukocytes, squeeze between the cells and enter the milk

168
Q

Neurons from spinal cord stimulate production and release of oxytocin from ___ and ___nuclei in response to suckling

A

Paraventricular; supraoptic

169
Q

4 effects of suckling on hormone release

A
  1. Activates afferent neural pathway from breast to spinal cord, then to hypothalamus
  2. Inhibition of dopamine release
  3. Spinal cord neurons stimulate production and release of oxytocin from posterior pituitary
  4. Spinal cord neurons inhibit arcuate and preoptic area of hypothalamus causing decrease in GnRH production, ultimately inhibiting ovarian cycle
170
Q

Describe cessation of lactation

A

When the suckling stimulus is discontinued, milk accumulates —> distention and mechanical atrophy of epithelial structures, rupture of alveolar walls, compression of capillaries resulting in alveolar hypoxia

Cell and glandular debris are phagocytosed

Lobular-acinar structures become smaller

Ductal system predominates

Full involution can take up to 3 mos

*GIGU I (67 decks)

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