Pregnancy Physiology Flashcards
describe aspects of CV adaptation to pregnancy
- blood vol increases (35%)
- syst. vasc. resist decr. (15-21%)
- CO, SV, HR, all incr
- BP dec, hgb decr
what cell types are resp for remodeling of the spiral arteries
extravillous cytotrophoblasts
the spiral arteries in pregnancy are remodeled to allow ?
high flow, low resistance
systemic vasculature during pregnancy undergoes what type of changes?
less fibrin, more elastin = reduced vasomotor tone = incr. compliance - total periph. resistance is decr. 20-25%, this decr in afterload contributes to the incr. CO.
-MMPs contribute to this process by remodeling the ECM around the arteries
decidualization of the endometrium is?
cells have become lg pale cells susc. to invasion by the trophoblasts
what factors control vasc. remodeling and when is it completed by what time?
- hCG, P4(prog), E2, also antiangiogenic factors like sol. VEFGRs and endoglin are nmly decreased whereas PlGF (pl. growth factor) is increased. These may look diff. in pts w/ preeclampsia
- placental remod. is done by 20 weeks, but maternal adaptation cont. til the end
why does hct drop during pregnancy?
b/c the plasma vol incr. more compared to the incr in erythrocytes and thus the ratio is lower, hct lower. physiologic anemia
changes in the heart during pregnancy
ventricular remodeling = physiologic left vent. hypertrophy which is caused by an incr. in cardiac myocytes w/o fibrin deposition. this is similar to the effects seen in exercise.
-ANP and BNP are rel from the heart musc in resp to stretching
GFR changes in pregnancy
GFR increases w/ the incr. in CO and blood flow. Nml Cr may be avg of 0.4 instead of 0.9. Also, the pressure of the fetus can cause dilation of the urinary collection system = hydronephrosis
Respiratory changes during pregnancy
the diaphragm is elev, the ribs expand and respiration becomes more diaphrgmtic.
Total lung capac is decr, and dead space is incr - so the RR incr. to blow off the CO2 that would otherwise accumulate and 02 intake incr.
Nml ABG values in pregnancy
Ph 7.4-.45, pCO2 = 28-32, pO2 = 101-106, HCO3 = 18-21 this is a slight respiratory alkalosis with a metabolic compensation.
Hormonal changes in prenancy related to fat and metabolism
Pregnancy looks v. similar to obesity. Leptin, TNF-a, and Cort all incr. and they display insulin and leptin resistance resistance. Insulin resistance may contribute to incr. circulating levels of fats, etc which may contribute to their transport across the placenta.
majority of leptin incr. in preg comes from
the placenta
when cort is increased in preg, how does this affect the fetus?
Cort is inactivated in the placenta by 11BHSD2 which conv. it to inactive corticosterone and so the fetus is no affected. Cort in the mother may incr. circ levels of FFA’s and contribute to fat deposition in the fetus. if there is a problem with this enzyme it can lead to problems, growth restriction.
sev. mech of maternofetal transfer located on the syncytiotrphblst which has microvilli projecting into the intervillous space which is where the maternal blood pools=
- endo/exocytosis = ex. immunoglobulins
- lipophillic diffusion = resp. gases
- paracellular diff. = hydrophobic molecules, eg. Na, Ca, K
- prot-med. transport = AAs (FA transport prot), Glc (GLUTs), etc.