Pregnancy B&B Flashcards
to which receptors does HCG (human chorionic gonadotropin) bind and why does this make sense?
HCG binds LH receptors in corpus luteum to maintain it during pregnancy (so progesterone release continues)
recall HCG shares same alpha subunit as LH, FSH, and TSH
what is the importance of HCG (human chorionic gonadotropin) maintaining the corpus luteum?
corpus luteum releases progesterone, which prevents menstruation (so pregnancy is not lost!)
corpus luteum maintains pregnancy for first 10 weeks (then placenta takes over)
how is pregnancy maintained after first 10 weeks?
first 10 weeks - corpus luteum (maintained by HCG) produces progesterone
after 10 weeks - syncytiotrophoblasts (outer layer of placenta) begin secreting progesterone to maintain pregnancy going forward
[recall progesterone prevents menstruation]
where does human placental lactogen come from and what is its purpose?
aka chorionic somatomammotropin: peptide hormone produced by syncytiotrophoblasts during pregnancy
blocks the effects of insulin, raising blood glucose + promoting fatty acid/ protein breakdown by the mother, which is good for growth of the baby
this is why pregnant women may develop gestational diabetes!
why does gestational diabetes occur and how is it screened for?
syncytiotrophoblasts produce human placental lactogen during pregnancy - peptide hormone which induces anti-insulin state —> raising blood glucose + promoting fatty acid/ protein breakdown by the mother, which is good for growth of the baby
screen for gestational diabetes with serum glucose because glycosuria occurs in normal pregnancy!
explain why pregnant women will appear mildly anemic in blood work?
pregnancy causes a rise in both total plasma volume and production of EPO (increases RBC mass)
however, rise in volume > rise in RBC, resulting in dilutional anemia (decreased Hct)
how does pregnancy affect the cardiovascular system?
CO increases due to increased preload (via rise in blood volume) + decreased afterload (due to fall in SVR*) + slight rise in HR
*SVR falls because the placenta is a low resistance system that is placed in parallel to the body system
is placental circulation during pregnancy placed in parallel or in series to that of the body and why does this matter?
placental circulation is in parallel to the body, necessarily lowering systemic vascular resistance (SVR)
recall parallel resistance is 1/Rt = 1/R1 + 1/R2 …
while series resistance is Rt = R1 + R2 …
if the placenta was in series, it would necessarily raise SVP (bad), but by being in parallel, it essentially provides an alternative route for blood, cause SVP to DECREASE
this is true for mother and baby, which explains why SVP raises in baby after birth, allowing the L side of heart to have a great enough pressure to close the foramen ovale
why do some women complain of palpitations while lying flat during the later stages of pregnancy?
large baby compresses the IVC while lying flat, causing decreased venous return (preload) and subsequent supine hypotension
reflex tachycardia may produce symptoms such as palpitations
how does pregnancy affect coagulation?
pregnancy is hypercoagulable state due to increased fibrinogen and decreased protein S (anti-coagulate)
fetus also obstructs venous return by placing pressure on the IVC, making DVTs common
[probably evolved as protection against blood loss at delivery]
how does pregnancy affect the respiratory system?
tidal volume increases because there is more CO2 to exhale (due to baby’s metabolism) and ventilation increases
respiratory rate is mostly unchanged
how is preterm labor defined
labor before 37 weeks
(normally occurs at 40 weeks)
how are terbutaline and ritodrine used in premature contractions?
terbutaline and ritodrine are beta2 agonists —> increase cAMP to trigger relaxation of uterine smooth muscle, inhibiting contractions
what is the Apgar Score used for?
used to assess health of newborn immediately after birth (minute 1 and 5)
10 point score system, assign value of 0/1/2 for 5 categories (HR, respiratory effort, muscle tone, reflex irritability, skin color)
score less/equal to 3 at 5 minutes is associated with permanent neurological damage (ex, cerebral palsy)
what are mifepristone and misoprostol used for?
combined to cause medical abortion
mifepristone: anti-progesterone —> prevents implantation
misoprostol: synthetic prostaglandin E1 analog —> induces uterine contractions
only work in uterus, NOT used in ectopic pregnancy! (methotrexate used instead)
