7 - fetal physiology Flashcards
what transports oxygenated blood to the fetus?
umbilical vein
what transports deoxygenated blood to the fetus?
umbilical artery
what factors promote oxygen exchange at the placenta to the fetus?
- increased maternal 2,3 DBG - reduced Hb affinity for oxygen
- fetal specific Hb - higher affinity for oxygen (not bind 2,3 DPG as effectively)
- double Bohr effect
what is the double Bohr effect?
maternal side: high co2 so low pH - reduced Hb affinity for oxygen - gives up oxygen readily to fetus
fetal side: low co2 so high pH - increased Hb affinity for oxygen - readily accepts oxygen from the maternal side
how does co2 exchange occur?
low co2 in maternal circulation as pregnancy causes hyperventilation
Haldone effect
what is the haldone effect?
As Hb give us oxygen, it can accept increasing amounts of co2
fetus gives up co2 as o2 is accepted
no net change in local pco2
what are the three shunts in the fetus?
DUCTUS VENOUSUS
FORAMEN OVALE
DUCTUS ARTERIOSUS
what does the ductus venosus do?
by-pass the liver
blood goes from placenta –> IVC
what does the foramen ovale do?
shunts the right ventricle
blood goes RA –> LA
what does the ductus arteriosus do?
by-pass the lungs
blood goes PT –> aorta
what is the fetal response to hypoxia?
- bradycardia = vagal stimulation
- redistribution of blood flow to protect blood supply to the heart and brain
- slow HR
- HbF and increased [Hb]
what are the hormones for fetal development?
insulin, IGF, EGF, TGF
what is symmetrical growth restriction?
affects the whole body equally - whole foetus is involed
what is asymmetrical growth restriction?
is head sparing
what is amniotic fluid made from?
amniotic urine
