9. foetal growth and development (workbook)

Question 1

what does the foetus rely heavily upon maternal glucose for?

Answer 1

to drive glucose across the placenta and support foetal growth and development

Question 2

when does foetal insulin secretion commence?

Answer 2

at week 10

Question 3

can the foetus excrete bilirubin via its gut?

Answer 3

no

Question 4

what effect does this have on foetal bilirubin? (can’t excrete via gut)

Answer 4

bilirubin is therefore not conjugated, and so passes across to the maternal circulation

Question 5

as the neonate is not able to immediately able to deal with bilirubin, what condition is not uncommon?

Answer 5

neonate jaundice

Question 6

what forms a major part of the amniotic fluid?

Answer 6

the foetal kidneys produce urine - forming major part of amniotic fluid
particularly late in gestation

Question 7

what constantly happens to the amniotic fluid?

Answer 7

constantly swallowed, so the gut absorbs water and electrolytes, leaving debris to accumulate (together with debris from the developing gut)

Question 8

where does debris from amniotic fluid and developing gut accumulate?

Answer 8

in the foetal large bowel

Question 9

what is the debris accumulating in foetal large bowel known as?

Answer 9

meconium

Question 10

when is meconium usually excreted?

Answer 10

ONLY excreted by a foetus in distress e.g. foetal hypoxia

Question 11

what can amniotic fluid volume reach a maximum of?

Answer 11

1l around 38 weeks, but may fall as labour nears

Question 12

where are cells within the amniotic fluid derived from?

Answer 12

the amnion and from the foetus

Question 13

what is made by amniocentesis?

Answer 13

biochemical and cytological studies of the fluid are made by amniocentesis

Question 14

what is amniocentesis?

Answer 14

amniotic fluid test

a small amount of amniotic fluid, which contains foetal tissues, is sampled from the amniotic sac

Question 15

what is amniocentesis used to assess?

Answer 15

presence of neural tube defects, chromosomal abnormalities e.g. Down’s syndrome etc.

Question 16

in early pregnancy, where is amniotic fluid likely to derive from?

Answer 16

by dialysis of foetal and maternal extracellular compartments with some exchange occuring across the foetal skin

Question 17

later on in pregnancy, what contributes to the volume of amniotic fluid?

Answer 17

foetal urine
(with functional maturation of the foetal kidney)

Question 18

when the foetus swallows amniotic fluid, where is it then processed?

Answer 18

through the foetal gut and kidneys

Question 19

how are amniotic fluid volumes assessed?

Answer 19

by ultrasound

Question 20

what is an excess of amniotic fluid volumes known as?

Answer 20

polyhydramnios

Question 21

what is polyhydramnios associated with?

Answer 21

oesophageal or duodenal atresia (no opening) and CNS abnormalities (coordinate the movements)

Question 22

what is a low amniotic fluid volume known as?

Answer 22

oligohydramnios

Question 23

what is oligohydramnios suggestive of?

Answer 23

poor / absent renal function
OR
reduced placental function e.g. in pre-eclampsia

Question 24

when can withdrawal from pain be elicited?

Answer 24

at 15 weeks

Question 25

when does thalamo-cortical projections reach maturity?

Answer 25

until week 29

Question 26

when is completion of myelination in cortocospinal tract complete?

Answer 26

not until into the post-natal period

BUT MSK movements are essential for foetal growth

Question 27

what does placenta progesterone promote?

Answer 27

foetal corticosteroid production especially near term

Question 28

what is vital for foetal physiology?

Answer 28

placental steroid hormones (oestrogen and progesterone)

especially in CVS function

Question 29

what is mediated via thyroid hormones active from week 12?

Answer 29

nervous system development

bone and hair growth

Question 30

what does the liver store?

Answer 30

large amounts of glycogen

Question 31

what is the large amounts of glycogen store reflected in?

Answer 31

changes in foetal abdominal circumference

Question 32

what induces the neonate to take its first breath at birth?

Answer 32

a combination of physical trauma and cold temperatures

Question 33

what does the neonate taking its first breath result in?

Answer 33

dramatic reduction in pulmonary vascular resistance and a dramatic rise in arterial pO2

Question 34

what does a fall in pulmonary vascular resistance cause?

Answer 34

left atrial pressure to rise in respect to the right atrial pressure, so closing the foramen ovale

Question 35

what happens to the foetal shunts after taking the first breath? why?

Answer 35

Smooth muscle sensitive to high pO2 in the wall of the ductus arteriosus
contracts to close the ductus (high pO2 closes shunt between pulmonary artery to aorta)

Question 36

when are both shunts closed off completely?

Answer 36

within a few weeks

Question 37

which duct remains open after birth?

Answer 37

ductus venosus variably remains open for several days after birth, but closes within two - three months

Question 38

what happens to the ductus venosus to close?

Answer 38

a sphincter in the vessel constricts shortly after birth, re-directing all blood through the liver sinusoids
(this process is regulated by pO2 levels)