Foetal and Neonatal Physiology

Question 1

What is the greasy substance which protects the skin of an unborn baby?

Answer 1

Vermix

Question 2

What is the name given to the five stages of Lung development? How long does each stage take?

Answer 2

Embryonic (5 weeks)
Pseudo-glandular (10 weeks)
Canalicular (10 weeks)
Saccular / terminal sac (10 weeks)
Alveolar (5 weeks)

Question 3

In a baby’s lungs, from what of the five developmental stages is gas exchange possible?

Answer 3

Terminal sac stage (>25 weeks)

Question 4

Give examples of congenital conditions which affect lung development in a baby?

Answer 4

• Pulmonary hypoplasia (can be caused by Diaphragmatic hernia)

Question 5

At what stage is surfactant produced in a pregnancy?

Answer 5

Last 8 weeks of pregnancy (in the third trimester)

Question 6

What is the role of pulmonary surfactant?

Answer 6

Phospholipid, whereby the hydrophobic / hydrophillic interfaces adsorb the air-water interface of alveoli, reducing surface tension

Question 7

Babies born before surfactant production suffer with…?

Answer 7

Respiratory distress syndrome (RDS)

Question 8

Give 6 examples of causes for where a baby might have a pulmonary surfactant deficiency

Answer 8

1. Congenital absence
2. Prematurity
3. Infection
4. Acidosis
5. Hypothermia
6. Meconium aspiration

Question 9

What drugs can be prescribed to the mother of an unborn baby which may be pre-term to reduce the risk of RDS?

Answer 9

Antenatal / Maternal steroids

Question 10

What cells produce pulmonary surfactant?

Answer 10

Type II Pneumocytes

Question 11

On an X-ray, how might a newborn baby with RDS look like?

Answer 11

Ground glass appearance

Question 12

What is the definition of pneumothorax?

Answer 12

Collapsed lung, caused by air entry between the lung and chest wall -> Collapse

Question 13

What two components is the placenta derived from?

Answer 13

Uterine wall & Trophoblastic tissue

Question 14

What is arterial supply and venous supply of the umbilical cord?

Answer 14

2 Umbilical arteries (de-oxygenated blood)

1 Umbilical vein (oxygenated blood)

Question 15

What are the two foetal cardiac shunts?

Answer 15

1. Ductus arteriosus (Pulmonary artery -> Aorta)

2. Foramen ovale (RA -> LA)

Question 16

What is the Ductus Venosus?

Answer 16

A structure which shunts left umbilical vein blood flow directly into the IVC, bypassing the liver

Question 17

What lipid compound maintains patent Ductus Arteriosus?

Answer 17

Prostaglandins

Question 18

Aside from surgery, what can be administered to close a patent Ductus Arteriosis?

Answer 18

Prostaglandin Inhibitors

Question 19

What is Hypoplastic Left Heart Syndrome?

Answer 19

Congenital heart defect, where left side of heart is severely underdeveloped

Question 20

What is PPHN?

Answer 20

Persistent Pulmonary Hypertension of a Newborn

Question 21

Describe the pathophysiology of PPNH (Persistent Pulmonary Hypertension of the Newborn)

Answer 21

• Stiff lungs -> pulmonary arterioles stay constricted
• Pulmonary pressures are high (pulmonary hypertension)
• Blood difficult to pump through lungs
• Easier to go through ductus arteriosus and R->L shunt at foramen ovale
• Persistent foetal circulation

Question 22

When does Foetal Hb switch to Adult Hb?

Answer 22

Drops at ten weeks