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58 Cards in this Set

  • Front
  • Back
What are the 4 peptide hormones involved in pregnancy?
1) hCG
2) hPL (hCS)
3) relaxin
4) prolactin
What cells produce hCG?
What subunit of hCG is used to detect prenancy?
Beta-subunit is selected for by an radiolabeled Ab.
What is the endocrine effect of hCG on the ovary?
Continues to produce progesterone and estradiol, saving the corpus luteum.
What feedback control is critical in hCG release?
hCG prevents FSH/LH secretion, because no more follicles should allowed to develop.
What cells produce human placental lactogen (HPL)?
What is the function of HPL?
In a hypoglycemic condition, HPL causes the mother to become insulin resistant so that an increase in plasma glucose and free fatty acids can be brought to the fetus.
What is relaxin?
Relaxer of myometrial contractions in early pregnancy, and relaxer of pelvic bone and pubic symphysis during parturition.
Where is relaxin produced?
In the corpus luteum as well as the placenta.
What is prolactin?
A mammotroph that stimulates lactation.
What stimulates prolactin secretion?
What prevents significant lactation from occurring?
High levels of progesterone and estrogen.
Where are fetal estrogens primarily produced in a pregnant woman?
How does the placenta obtain cholesterol for estrogen production?
Maternal HDL almost exclusively. Placenta cannot produce cholesterol on its own.
What enzyme is necessary to synthesize estrogen in the placenta?
17,18-desmolase. Placenta lacks this enzyme.
Pregnenolone --> Progesterone --(desmolase)--> DHEA-S --> Estradiol --> 16-OH-DHEA-S --> Estriol
Where does the placenta get desmoloase from?
Mother and fetus.
What does 3-beta-OH-dehydrogenase do in the fetus?
Converts pregnenolone to progesterone.
What does 17,18-desmolase do in the placenta?
Converts progesterone to DHEA-S.
What is the major source of fetal estrogen?
Fetal adrenal gland
What is the result of conjugating DHEA with S?
More water soluble, less bioactive.
What happens to DHEA-S in the fetus?
It will get hydroxylated in the fetal liver or else diffuse back to the placenta. Hydroxylated DHEA-S will also eventually diffuse back to the placenta and become estriol.
What happens to DHEA-S in the placenta?
Converted to estradiol and estrone (abundant sulfatase and aromatase).
What is significant about estriol?
It can only be synthesized in the fetal liver from hydroxylated DHEA-S; not anywhere else.
It can be measured as a marker for fetal well-being.
What is a major estrogen of pregnancy?
Estriol is abundant, but it has weak estrogenic activity.
What hormone is directly responsible for sustaining the fetus?
How does progesterone affect uterine contractions?
Inhibits uterine contractions to protect the fetus by inhibiting prostaglandin, downregulating oxytocin receptors, and promoting myometrial relaxation.
How does the fetus prevent maternal alloantigenic attack?
Progesterone suppresses T-cell and macrophage activation, and reduces the number of leukocytes available.
What effect does progesterone have on lactation?
Mammogenesis - forms alveolar pouches, and increase ability to milk secretion.
What hormone is responsible for parturition?
How does estrogen affect the myometrium?
Stimulates its growth to prepare for parturition.
How does estrogen prepare the mother physically for delivery of the baby?
In conjunction with relaxin, softens the pubic symphysis and softens the pelvic ligaments.
How does pregnancy affect the heart?
Increases cardiac output by increasing stroke volume and heart rate.
What happens to the mean arterial blood pressure in a pregnant woman?
Decreases since total peripheral resistance drops more than cardiac output increases. Blood vessels dilate.
What happens to blood volume in a pregnant women?
Increases by as much as 50% in the 2nd trimester.
What happens to regional blood flow in a pregnant woman?
Increases to the uterus, skin (maintain body temp), and kidney.
What happens to venous pressure in a pregnant woman?
Elevates in the lower extremeties due to backup in the presence of the fetus, compromising venous return.
What happens to the blood in a pregnant woman?
Plasma volume increases, hematocrit decreases, leukocytes increase.
What happens to the respiratory system in a pregnant woman?
Increased tidal volume, maintain the same frequency --> Increase alveolar ventilation. Possible hyperventilation may ensue (respiratory alkalosis, bicarb is excreted in the urine).
What happens to the diaphragm of a pregnant woman?
Gets elevated and total lung capacity increases.
What happens to the kidney of a pregnant woman?
Increased renal blood flow, increased glomerular filtration, increased renal perfusion.
What happens to the GI system of a pregnant woman?
Slowed motility to increase absorption, LES tone is decreased due to progesterone and acid reflux is more common.
What happens to the hypothalamus-pituitary-gonadal axis of a pregnant woman?
High concentration of estrogen and progesterone suppresses its secretion. Prolactin secretion is increased due to pituitary lactotroph growth.
What happens to a woman's metabolism in the first half of pregnancy?
Mother is storing up fat, glycogen, and nutrients to feed the future baby - increased insulin sensitivity.
What happens to a woman's metabolism in the second half of pregnancy?
Accelerated starvation because glucose and fatty acids are all being released from storage for the fetus - decreased insulin sensitivity.
What hormone regulates the catabolic state of a pregnant woman in the second half of gestation?
Human chorionic somatomammotropin (hCS or HPL).
What ratio is necessary initiate labor?
Low ratio of progesterone:estrogen.
What is the role of CRH?
Enhances the effects of prostaglandins and oxytocin, which aid in contraction.
CRH levels peak during parturition, along with estrogen levels.
What causes mymoetrial cell contractions?
Decrease in progesterone:estrogen ratio.
What is the role of oxytocin in a pregnant woman?
Increases uterine smooth muscle contractions.
What hormone stimulates the upregulation of oxytocin receptors in myometrial tissues?
When does the uterus become sensitive to oxytocin?
After 20 weeks.
What does oxytocin stimulate the release of?
Prostaglandins, which stimulate contractions.
What does relaxin do during pregnancy?
Keeps uterine quiet during pregnancy to prevent harm to the fetus, and softens the cervix and pelvic ligaments prior to labor.
How does an increase in estrogen in late pregnancy affect the uterine myometrium?
Increases the ability of myometrium to contract by upregulating oxytocin receptors.
What effect does prolactin have on reproductive function?
Suppresses GnRH, a somewhat unreliable contraceptive.
What is colostrum?
Pre-milk that contains little fat.
What is the role of oxytocin following delivery?
Contract myoepithelial cells in the breast for "milk letdown."
What is the sequence of events for "milk letdown"?
Sucking stimulates the breast --> Dopamine is inhibited --> Prolactin is released --> Milk is produced.
Neural input (seeing infant, hearing it cry) --> Oxytocin release from SON and PVN --> breast myoepithelium contracts --> milk is "letdown."
Neural input --> inhibits GnRH --> suppression of FSH/LH.