EXAM 3: Fetal Circulation Flashcards
Parallel circuit
Both right and left ventricles provide systemic blood flow
Admixture blood
oxygenated with deoxygenated blood
PVR is because
High ; clamped down fluid filled
SVR is________
low
Placenta makes
SVR stay low
Right to left shunt
Right heart bypass lungs
Blood comes from the __________to the placenta
UMBILICAL VEIN Ductus venosus
The ductus venosus joined with
Inferior vena cava , and blood coming from LE
The ductus arteriosus
2nd place of shunting Right to left , bypass lung
Fetal circulation Right vs LEFT
RV output 2x that of left
Ratio of PVR to SVR
2:1 Right to left ratio
When placenta is removed
SPINAL ARTERY starts bleeding Uterus start Contracting stop mechanically from bleeding
Anesthesia Gases do what to the uterus
Relaxes uterus; may increase bleeding of spinal arteries after placenta has been cut off run MAC less percentage
INTERVILLUS SPACE Does mother and fetus blood mix? Thin membrane allows
where blood exchange happens Blood of fetus and mother’s blood DONT MIX passage of nutrients
RH factor relevant
Rh factor relevant in 2nd pregnancy
****Uteroplacental Perfusion: Originates from
the uterine and ovarian arteries
Blood flow to intervillous space
Maternal blood enters the basal plate of the placenta into the intervillous space • Nutrient exchange occurs with fetal blood coursing through the villi
2 circulations separate
• Normally, the two circulations are separate with no mixing
Uterine blood flow increases___ Prepreg. Level Pregnant _______ml at term
dramatically 50-100 ml/min PREGNANT 700-900ml min at term
Cardiac output to uterus increase from ______to ________
5% to approx 12% at term within the uterus , approxi 90% of blood flow is to the iNTERVILLOUS SPACE>
• Hemodynamic changes are result of_______ • Generalized systemic reduction in sensitivity to_______
-altered vascular responsiveness to endogenous vasoactive substances -vasoconstrictors during pregnancy
Uterine vascular responsiveness to vasoconstrictors What happens in PRE-ECLAMPSIA
• ↓ (meaning BP shouldn’t be higher than normal) Mother who developed preeclampsia lack the systemic reduction in sensitivity to catecholamines. LACK of refractoriness to resistance –> HTN
Uterine vessels are more sensitive to____________
alpha agonists than systemic vessels in general • More uterine vasoconstriction (increase vascular tone of mother, baby does worse, HR decelerates)
Changes in vascular reactivity during pregnancy may be due to:
• Altered receptor number and function (LESS) • Altered metabolism and clearance of drugs (increase BV) • Altered release of endogenous vasodilators or constrictors • Altered sensitivity to endogenous vasodilators (PGE2 and NO) or constrictors

