Foetal cardiopulmonary physiology

Question 1

Foetus grows in a relatively hypoxaemic state.

The foetus receives blood from the placenta.

1. From the placenta, oxygenated blood enters the umbilical veins.
2. Then it enters ductus venosis in the liver and enters the hepatic veins
3. Then it enters the inferior vena cava and finally into the right atrium
4. From the right atrium, blood flows through the foramen oval (defect in the atrial septum) into the left atrium
   => this is because there is greater pressure on the right side receiving blood from mother
5. Blood flows into left atrium to the left ventricle, into the aorta
6. Blood entering from pulmonary artery is shunted to the aorta via ductus arteriosus

=> There is mixing of deoxygenated blood from the foetal circulation entering from the superior vena cava

=> Not much blood going into lungs as the vasculature is very primitive and not functional

Answer 1

=> Foetal dissociation curve towards the left meaning higher affinity to bind oxygen with less partial pressure of oxygen

=> Cells in ductus arteriosus and ductus venosus which is sensitive to oxygen and relative hypoxaemia keeps the ducts patent

Question 2

Signs & symptoms of Heart Failure (for reference)

Answer 2

Symptoms:
=> Tachypnoea
=> Poor feeding
=> Faltering growth
=> Cold hands & feet
=> Sweating
=> Vomiting 

Signs:
=> Tachypnoea
=> Thin
=> Displaced apex
=> Dynamic precordium
=> Hepatomegaly