Foetal Circulation

Excerpts from previous naturopathy assignments HLT60512. Brief Description of Foetal Circulation

Standford Children’s Health Hospital describes Foetal Circulation as follows: Foetal circulation allows for nutrients to be transferred from the mother to foetus, and for wasted to be carried away from the amniotic fluid. The umbilical cord is connected to the placenta in the mother’s uterus, and it receive nutrition and oxygen via the blood supply in the placenta and umbilical cord and delivers waste back to the placenta (via umbilical cord) to the mothers circulation to be detoxified (Standford Childrens Health, 2018).

Valves called shunts direct blood around the body, they’re necessary to modulate blood flow to part of the body that are not developed enough to receive blood flow yet for example the foramen ovale directs blood away from the lungs whilst directing blood from the right atrium of the heart to the left atrium; and the ductus arteriosus directs blood away from the pulmonary artery to the aorta (Standford Childrens Health, 2018).

The flow towards the liver is instead split into three different branches via the ductus venosus and blood is sent to the inferior vena cava and then to the right atrium of the heart. Only a small amount of this blood goes to the liver to give it necessary oxygen and nutrients (Standford Childrens Health, 2018).

At birth the lungs begin to expand and the alveoli in the lungs are cleared of fluid. Baby’s blood pressure increases and reduction in pulmonary pressures which promote closure of the shunts. This completes the transition of foetal to newborn circulation (Standford Childrens Health, 2018).

Foetal Circulation occurs via the placenta and the umbilical cord. The mother supply nutrients and oxygen through the blood and waste is returned to the mother’s circulation for detoxification.

Standford Children’s Hospital gives the following description of Foetal Circulation in the Heart:

• Blood enters the right atrium, the chamber on the upper right side of the heart. When the blood enters the right atrium, most of it flows through the foramen ovale into the left atrium.
• Blood then passes into the left ventricle (lower chamber of the heart) and then to the aorta, (the large artery coming from the heart).
• From the aorta, blood is sent to the heart muscle itself in addition to the brain. After circulating there, the blood returns to the right atrium of the heart through the superior vena cava. About two thirds of the blood will pass through the foramen ovale as described above, but the remaining one third will pass into the right ventricle, toward the lungs.
• In the foetus, the placenta does the work of breathing instead of the lungs. As a result, only a small amount of the blood continues on to the lungs. Most of this blood is bypassed or shunted away from the lungs through the ductus arteriosus to the aorta. Most of the circulation to the lower body is supplied by blood passing through the ductus arteriosus.
• This blood then enters the umbilical arteries and flows into the placenta. In the placenta, carbon dioxide and waste products are released into the mother’s circulatory system, and oxygen and nutrients from the mother’s blood are released into the foetus’ blood (Standford Childrens Health, 2018)

Heather Indiana Rose

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