472 2-endocrine regulationof pregnancy and 2- physiology changes

prolactin is a

protein hormone

FSH,LH,hCG are

glycoproteins (glucose and protein tgt)

oxytocin is a

polypeptide

estrogens, progestins, testosterone (3 primary reprod hormones) are

steroids

prostaglandins and thromboxanes (regulate vascular helath) are

fatty acids

endocrine regulation during pregnancy is primarily by the

hypothalamic-pituitary-ovarian system

which hormones act on gonads (gonadotropins)

fsh and LH- gonadotropins

hypothalamus secretes ___ which stimulates anterior pituitary to release ____ as they stimulate ovaries

hypothalamus secretes gonadotropin releasing hormone which stimulates anterior pituitary to release FSH and LH as they stimulate ovaries

all hormones secreted by anterior pituitary except oxytocin and anti diuretic hormone which is secreted by posterior pituitary

how does hpo axis work

pregnancy as a stress state

pregnancy increases hpa axis acitivity which increases cortisol

what does progesterone do

• prepares wall of the uterus so that the lining is able to accpet a fertilized egg. so egg can be implanted and develop

• a fert egg that becomes implanted in uterus will form placenta

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• the ___ is a major source of progesterone during the first 10 weeks gestation

• what is the luteal placental shift

• the corpus luteam is a major source of progesterone during the first 10 weeks gestation

• then placenta produces progesterone during full period of pregnancy.

• LPS= when placenta takes over corpus luteum job in mkaing progestrone around 6-10 weeks of gestation

• a delayed shift or insufficient progesterone production from either source can inc risk of pregnancy lossand progesterone supplementation is often used in IVF to bridge this gap

what does the placenta use primarily for progesterone production

maternal cholesterol and LDL

what does progesterone do during pregnancy

• stimulates development of mammary glands in breasts that are responsible for milk production

• increases sensitivity of maternal respiratory center for CO2 (inc CO2 levles kills fetus)

• suppresses maternal immunological responses to fetal antigens, preventing rejectino of fetus

• relaxes smooth muscle in GI and urinary systems

• inc basal body temp and sodium and chloride excretion

the primary function of progesterone is to

serve as a substrate pool for fetal adrenal gland productin of glucocorticoids, which plays key roles in fetal growth and development as well as regulation of macronutrient metabolism

aka

progesterone provides a starting material that the fetal adrenal glands can use to make glucocorticoids, which help the fetus grow and develop.

3 major estrogens? and which is most potent form for non pregnant

estrone (e1) estradial (e2) estriol (e3)

• estradiol is most potent form

all estrogens inc but estriol increases rapdily in pregnancy (secreted by placneta)

estrogens promote myometrial vasodilation

the primary source of estriol precursors (dheas) is the

fetal adrenal gland, under stimulation by the fetus’ acth

dheas is hydroxylated in the fetal liver and further metabilized by placenta to form estriol

hCG funtions

hCG maintains corpus luteum in early pregnancy to ensure progesterone secretion until placenta can take over.

• conc of hcg in maternal serum foubles every 2-3 days until 60-90days after conception and starts to plateau by 100-130 days

also stimulates adrenal glands to secrete testosterone and cortisol

hPL functions

• promotes fetal growth by alterign maternal protien, carb, fat metabolism

• primary role is to regulate glucose availabiltiy to fetus (its an insulin antagonist)

• reduces glucose uptake and use by maternal cells by increases use of fat as an energy substrate

what gets transferred from mother to fetus and back vice versa

cardiovascular system chancges in mother in pregnancy

• whats meant by physiologic anemia

cardiovasculat changes:

• mediated by estrogen, progesterone, prostaglandins

• cardiac output increased, heart rate increases then stabilizes

• heart rate inc from 15-20 bpm compared to nonpreg state

increase in blood volume:

• rise in blood volume correlates directly with fetal weight

• by. 32 weeks it is almost 50% increase

increase in RBC corresponds to increase in RBC volume

intravascular expansion is due to inc in plasma volume, leading to hemodilution

this “physiologic anemia” (cuz plasma volume inc more than RBC does) of pregnancy is reflected in lower hematocrit and gemoglobin

inc in RBCs not sufficient, not proportional to total blood volume which leads to hemodilution.

mother struggles to balance sodium leading to

intravasculr expansion die to inc in plasma volume =, leading to hemodilution

mechanism of hypervolemia (inc of volume of blood)

(due to estrogen)

estrogen increases

renin increases (enzyme, mainly in kidney )

angiotensin2 and aldosterone ( secreted by adrenal glands) inc

inc in extracellular fluid volume.

human chorionic somatomammotropin inc and prolactin inc

both of these result in inc blood volume

why is hyoervolemia essential

helps to meet demands of enlarged uterus and vascular system while maingtaining normal bp

protects mother from imparied venous return and hypotension with position changes

increase cutaneous blood flow which assists with heat dissipation

allow mother to tolerate blood loss postpartum

respiratory system chagnes

• inc in volume of air and gas exchange. enhances oxygen availability to and co2 removal from fetus

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• progesterone is a respiratory stimulant and inc sensitivity to co2. how?

Progesterone is a respiratory stimulant, and increases sensitivity to carbon dioxide by

decreasing the threshold of the respiratory center.

For example:

In non pregnant women an increase of 1mM Hg in PaCO2 results in a 1.5L/min increase in ventilation

But during pregnancy, the same 1mMHg increase in PaCO2 leads to a 6L/min increase in ventilation

This increased sensitivity in CO2 occurs mostly before 20 weeks gestation and leads todyspnea (shortness of breath) as well as hyperventilation

whats PaCO2 and PaO2

PaCO2: partial pressure of CO2 in blood. critiacal in regulating breathing levels oand maintianing body pH

PaO2: partial pressure of oxyegn in blod

hypercapnia, hypoxia, hypoxemia

Respiratory negative impacts:

l Hypercapnia: excessive carbon dioxide in blood

l Hypoxia: decreased oxygen in tissue

l Hypoxemia: decreased oxygen content in blood

hypoxemia not dangerous for getus but can turn into hypoxia which is dangerous for fetus

renal system changes

increased renal blood flow, corresponds to increase in renal size, wieght and volume

dilation of urinary tract occurs in 50% of women

increase in glomular filtration rate due to increased renal blood flow, and decreased colloid osmotic pressure, due to decrease in plasma proteins (albumin)

increase in gfr is necessary for successful pregnancy

GFR influences nutrtional status. what is proteinuria is it a concern and what associated with it?

renal excretion of aas, PROTEIN, glucose, water soluble vitamins and calcium increses

but excretion of serum urea, creatine, blood urea nitrogen and uric acid levels decreases

protein excretion (proteinuria) increases and is fairly common in preg and not a concern unless values inc more than 300mg/day

proteinuria associated with hypertension and high risk of pre eclampsia

glycosuria is also common

sodium balance is between two opposing mechanisms

factors promoting retention (estrogen) and factors promoting excretion (progesterone)

what is atrial natriuretic factor

atrial natriuretic factor is a powerful vasodilator secreted by heart muscle in response to high blood volume to promote sodium loss.

angiotensinogen is stimulated by

angiotensinogen is stimulated by inc estrogen levels

system is inc in first trimester

accumulation of sodium in preg is accompanied by water accumulation. both extra and intra component inc but larger increase in

extracellular water.

in total , 5-6 L of water is accumulated towards end of pregnancy

GI system chagnes

• what hrmone supresses appette wjat hormone stimulates appetite

pica

hormonally, estrogen tends to suppress appetite while progesterone stimulates appetite. both hormoens inc in pregnancy which is why may be hungry at 2am

progesterone acts on smooth muscles to decrease GI tone, leads to prolonged transit time inc absorptive capacity

height of duodenal villi increases

progesterone also inc brush border enzyme activity, incraeseing absorption

theory of lying on right side in later pregnancy

compresses the inferior vena cava and aorta and may decrease blood return to the heart