What colour are babies when they're born?
Hypoxic, deflated lungs
Swallowing amniotic fluid is a normal part of foetal homeostasis.
What condition can be caused by swallowing amniotic fluid following or during foetal distress?
Meconium aspiration syndrome
causes ARDS - meconium clogs up air spaces and neonate will become hypoxic
At what point in gestation do the alveoli develop?
So prematurity requires steroids to speed up lung development
What is produced from 26 weeks and is required for lung development?
What is the purpose of pulmonary surfactant?
Which cells produce it?
Reduce alveolar surface tension, allowing them to resist collapse
Type II pneumocytes
What does amniotic fluid consist of
a) early in the pregnancy
b) later in the pregnancy?
a) Maternal fluid
b) Foetal urine
A lack of amniotic fluid in the womb is related to a problem with which organs?
involved in amniotic fluid recycling
Which organs allow a baby to swallow and then filter amniotic fluid?
Why do babies cry when they are born?
Forcing air against a closed glottis pushes fluid from the air spaces to the interstitium
Which maternal antibody is passed across the placenta to the foetus?
In the first 10 - 20 minutes of life, is oxygen used to resuscitate babies?
Does more harm than good
How long should you wait before clamping a newborn's umbilical cord?
3 - 5 minutes
Allows adequate transfer of blood - clamping too early can lead to hypovolaemia and anaemia
What are the three shunts in the foetal circulation?
Ductus venosus (bypassing the liver)
Foramen ovale (right to left shunt in the heart)
Ductus arteriosus (bypassing pulmonary circulation)
In the foetus, the pulmonary circulation has a (high / low) resistance.
Does blood travel to the lungs in the foetus?
But a v small amount (around 7%), most of it is shunted from R heart to L heart
How many umbilical arteries and veins does a foetus have?
Which type of blood travels in each?
1x umbilical vein - OXYGENATED BLOOD FROM MOTHER
2x umbilical arteries - DEOXYGENATED BLOOD FROM FOETUS
Describe the pulmonary vascular resistance before birth.
Allows very little blood to travel to the lungs
Describe the systemic vascular resistance before birth.
Especially compared to the pulmonary resistance
Addition of placenta adds a massive 'length' to vasculature, reducing the resistance
What remnants of the
a) ductus venosus
b) foramen ovale
c) ductus arteriosus
can be found in adults?
a) Ligamentum teres of the liver
b) Oval fossa
c) Ligamentum arteriosum
Why does the foramen ovale close after birth?
Pulmonary vascular resistance drops, so blood goes to the lungs avoiding the shunt
Systemic vascular resistance increases, so it's harder to shunt blood from right heart to left heart
L pressure holds the valve shut and over time it fuses with the septum
What three factors contribute to the closing of the ductus arteriosus?
1. Reduced blood flow
2. Reduced Prostaglandin E2 produced by placenta
3. Smooth muscle CONTRACTS (unique response not found anywhere else)
After birth, the smooth muscle of the ductus arteriosus (relaxes / constricts).
constricts to reduce blood flow through shunt
Which chemical maintains the patency of the ductus arteriosus?
Which organ produces it?
Why does systemic vascular resistance decrease following birth?
Widespread vasodilation caused by oxygen
Loss of the 'length' of the placental circulation
Why does pulmonary vascular resistance drop following birth?
Oxygen is a vasodilator --> widespread vasodilation of the pulmonary vasculature
Which form of glucose is stored by the foetus before birth?
What is the advantage of this?
Loads of sugar stored for first few days post-natally
Which type of fat can be rapidly oxidised to produce energy?
Which process is brown fat useful for?
What is the function of
a) white fat
b) brown fat?
a) Energy storage
Where is brown fat found in the foetus?