Foetal circulation

Where does nutrition storage/detoxification take place in an adult?

Liver

Where does gas exchange take place in adults?

Lungs

Where does nutrition storage/detoxification and gas exchange take place in a foetus?

Placenta

What are the three major shunts and openings that the foetus develops to restrict blood flow to the liver and the lungs?

1. Ductus venosus

2. Ductus arteriosus

3. Oval foramen

What is the vascular shunt labeled A?

Ductus ateriosus

What is the vascular shunt labeled B?

Oval foramen

What is the vascular shunt labeled C?

Ductus venosus

Briefly describe the structure/location of the ductus venosus:

Runs adjacent to the portal vein (these combine and join that caudal vena cava)

It closes at birth due to pressure changes

Briefly describe the the role of the ductus venosus:

Shunts 50% of blood from the umbilical vein to the caudal vena cava bypassing the liver

Regulated by a sphincter

What are the three functions of the ductus arteriosus?

90% of blood in the pulmonary artery is shunted to the aorta to bypass the developing lungs

protects the lungs from overload

Exercises and develops the right ventricle

Briefly describe the location of the oval foramen:

Directly in line with the caudal vena cava (blood pressure opens the flap)

What is the function of the oval foramen?

Shunts blood from the right atrium to the left atrium away from the developing lung

What is the function of the umbilical vein?

Brings in oxygen and nutrient rich blood

What is the function of the two umbilical arteries?

Returns oxygen and nutrient depleted blood

What is the feature labeled A?

Brachicephalic trunk

What is the feature labeled B?

Oval foramen

What is the feature labeled C?

Ductus venosus

What is the feature labeled D?

Umbilical vein

What is the feature labeled E?

Subclavian arteries

What is the feature labeled F?

Umbilical arteries

Briefly describe the pressure changes in the lungs peri partum:

Pressure changes within the lungs as the new born breathes and placenta is abrupted

Briefly describe the closure of all three vascular shunts:

Closures are functional within hours and anatomical/permanent within days

They are controlled by pressure changes and chemical mediators

Briefly describe the closure of the ductus ateriosus:

Pressure changes in the lungs so blood is no longer diverted

Briefly describe the closure of the ductus venosus:

Due to reduced pressure in the umbilical vein

Briefly describe the closure of the oval foramen:

Pressure equalises at birth causing it to mechanically close

Prostaglandins cause permanent closure in a matter of days

What does patent ductus venosus mean?

Failure to close post partum

Means that blood still bypasses the liver and toxins remain in the blood

What would a failure of the oval foramen to close mean?

Blood would pass from the left to the right side of the heart changing oxygen saturation’s

Can leads to exercise intolerance

What would a failed closure of the ductus arteriousus mean?

Mixing of the blood in the right and left sides of the heart

Exercise intolerance

Lower oxygen saturation’s