Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
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?
|
Syncytiotrophoblasts.
|
|
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)?
|
Syncytiotrophoblasts.
|
|
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?
|
Estrogen.
|
|
What prevents significant lactation from occurring?
|
High levels of progesterone and estrogen.
|
|
Where are fetal estrogens primarily produced in a pregnant woman?
|
Placenta.
|
|
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?
|
Progesterone.
|
|
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?
|
Estrogen.
|
|
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?
|
Estrogen.
|
|
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. |