FOETAL AND NEONATAL PHYSIOLOGY

Question 1

what cause physiological hyperventilation in pregnancy and why is it important?

Answer 1

progesterone

it produces a drop in pCO2 which allows an effective concentration gradient for exchange with foetal blood

Question 2

where is foetal haemoglobin produced?

Answer 2

erythroid precursor cells and then… yolk sac, liver, spleen and bone marrow

Question 3

outline how the structure of adult and foetal Hb differ?

Answer 3

HbF has 2 alpha and 2 gamma subunits whilst HbA has 2 alpha and 2 beta subunits

Question 4

what has a higher affinity for oxygen, HbA or HbF?

Answer 4

HbF

Question 5

outline the double Bohr effect at the materno-foetal interface?

Answer 5

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

Question 6

outline the double Haldane effect at the materno-foetal interface?

Answer 6

HbF releases CO2 as it becomes oxygenated

HbA picks up the CO2 as it becomes deoxygenated

Question 7

what physiological response does the foetus have in acute hypoxia?

Answer 7

the foetus can redistribute blood flow to protect the supply to the heart and brain
foetal heart rate slows to reduce oxygen demands

Question 8

what can chronic hypoxaemia lead to?

Answer 8

IUGR, behavioural changes and development impacts, cellular damage in CNS

Question 9

why do neonates need to adapt to ex-utro conditions?

Answer 9

the placenta is removed and umbilical cord is clamped
different cardiac and respiratory physiology required ex-utero
metabolic and thermal stress

Question 10

why is it important that foetal and maternal blood do not mix?

Answer 10

they may have different blood types, Rh disease, less efficient oxygen transfer

Question 11

how does maternal blood arise at the placenta?

Answer 11

via spiral arteries perfusing intervillous spaces

Question 12

where does materno-foetal exchange occur?

Answer 12

at the chorionic villi in the placenta

Question 13

what vessels are found within the umbilical cord?

Answer 13

1 umbilical vein carrying nutrients and 2 umbilical arteries

Question 14

when is the utero-placental circulation fully established?

Answer 14

the end of the first trimester

Question 15

what carries blood to the foetus from the placenta?

Answer 15

umbilical vein

Question 16

what is it and why is the ductus venosos so important?

Answer 16

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

Question 17

outline foetal blood movement in the heart?

Answer 17

form the right atrium it is shunted into the left atrium via the foramen ovale then the left ventricle and out the aorta

Question 18

what’s the fucntion of the ductus arterioles?

Answer 18

it connects the pulmonary trunk to the aorta so blood can be shunted from the right ventricle/pulmonary trunk, to the aorta

Question 19

why is the ductus arteriosus important?

Answer 19

it keeps the blood away from lungs filled with amniotic fluid - lungs cannot take this pressure yet as they are not fully developed

Question 20

how does the placenta barrier have immune protection functions?

Answer 20

it prevents the transfer of pathogens as well as allowing antibodies to cross

Question 21

what hormones does the placenta release?

Answer 21

human chorionic gonadotropin, human placental lactogen, estrogens and progesterone

Question 21

what hormones does the placenta release?

Answer 21

human chorionic gonadotropin, human placental lactogen, estrogens and progesterone

Question 22

what is the main foetal energy source?

Answer 22

glucose

Question 23

why do babies get cold so fast?

Answer 23

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

Question 24

what are inherited metabolic disorders?

Answer 24

genetic conditions that result in metabolism problems

Question 25

how is amniotic fluid removed from the lungs at birth?

Answer 25

The pressure of the birth canal on your baby’s chest also releases fluid from their lungs. After birth, your baby’s cough, as well as air filling their lungs, should expel the remaining amniotic fluid.

Question 26

why is there roughly a 24 week cut off for viability?

Answer 26

as the terminal sac stage of lung development needs to be reached before the baby is born

Question 27

what is tracheal stenosis?

Answer 27

a narrowing of the windpipe

Question 28

what is pulmonary hypoplasia?

Answer 28

small, underdeveloped lungs that can affect not only breathing but also heart function, ability to feed, hearing and overall development.

Question 29

what can cause only 1 normal sized lung to develop?`

Answer 29

a diaphragmatic hernia can compress the lungs

Question 30

what is potters syndrome?

Answer 30

typical physical appearance caused by pressure in utero due to oligohydramnios, classically due to bilateral renal agenesis

Question 31

what’s the main cause of respiratory distress syndrome?

Answer 31

not enough functional type 2 alveoli cells producing surfactant

Question 32

what can be given during pregnancy to increase the amount of surfactant produced by the foetus?

Answer 32

glucocorticoid steroids

Question 33

what is Tetraology of fallot?

Answer 33

a rare condition categorised by pulmonary stenosis, thickened right ventricle wall, ventricular septal defect and overriding aorta