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