FOETAL AND NEONATAL PHYSIOLOGY Flashcards
what cause physiological hyperventilation in pregnancy and why is it important?
progesterone
it produces a drop in pCO2 which allows an effective concentration gradient for exchange with foetal blood
where is foetal haemoglobin produced?
erythroid precursor cells and then… yolk sac, liver, spleen and bone marrow
outline how the structure of adult and foetal Hb differ?
HbF has 2 alpha and 2 gamma subunits whilst HbA has 2 alpha and 2 beta subunits
what has a higher affinity for oxygen, HbA or HbF?
HbF
outline the double Bohr effect at the materno-foetal interface?
raised placental CO2 decreases oxygens affinity of HbA enhancing its release
decreasing pCO2 in foetal blood increases its affinity for oxygen so picks it up
outline the double Haldane effect at the materno-foetal interface?
HbF releases CO2 as it becomes oxygenated
HbA picks up the CO2 as it becomes deoxygenated
what physiological response does the foetus have in acute hypoxia?
the foetus can redistribute blood flow to protect the supply to the heart and brain
foetal heart rate slows to reduce oxygen demands
what can chronic hypoxaemia lead to?
IUGR, behavioural changes and development impacts, cellular damage in CNS
why do neonates need to adapt to ex-utro conditions?
the placenta is removed and umbilical cord is clamped
different cardiac and respiratory physiology required ex-utero
metabolic and thermal stress
why is it important that foetal and maternal blood do not mix?
they may have different blood types, Rh disease, less efficient oxygen transfer
how does maternal blood arise at the placenta?
via spiral arteries perfusing intervillous spaces
where does materno-foetal exchange occur?
at the chorionic villi in the placenta
what vessels are found within the umbilical cord?
1 umbilical vein carrying nutrients and 2 umbilical arteries
when is the utero-placental circulation fully established?
the end of the first trimester
what carries blood to the foetus from the placenta?
umbilical vein
what is it and why is the ductus venosos so important?
a shunt allowing blood to bypass the liver and enter the IVC so it can enter into the right atrium of the heart with the smallest possible drop in saturation
outline foetal blood movement in the heart?
form the right atrium it is shunted into the left atrium via the foramen ovale then the left ventricle and out the aorta
what’s the fucntion of the ductus arterioles?
it connects the pulmonary trunk to the aorta so blood can be shunted from the right ventricle/pulmonary trunk, to the aorta
why is the ductus arteriosus important?
it keeps the blood away from lungs filled with amniotic fluid - lungs cannot take this pressure yet as they are not fully developed
how does the placenta barrier have immune protection functions?
it prevents the transfer of pathogens as well as allowing antibodies to cross
what hormones does the placenta release?
human chorionic gonadotropin, human placental lactogen, estrogens and progesterone
what hormones does the placenta release?
human chorionic gonadotropin, human placental lactogen, estrogens and progesterone
what is the main foetal energy source?
glucose
why do babies get cold so fast?
they have a large SA for a small body mass- convection/conduction
loss of heat mainly from head- thin skull, not much hair, thin skin
not much fat
skeletal muscles not able to shiver yet
