Re: Whats advantage of having a ductus arteriosus, forman ovale as part of the

Dear Allie,

The advantage of having a ductus arteriosus and a foramen ovale is that the 
pulmonary circulation is bypassed.  The pulmonary circulation is those 
vessels which go through the lungs, but the lungs do not work when a baby 
is still in the uterus, because there is no air. Instead the baby gets 
oxygen from its mother's blood through the umbilical cord.  In an adult all 
the blood that gets pumped through the heart goes through the lungs to get 
oxygen, then to the rest of the body.  The blood first goes to the right 
side of the heart, then the lungs, then the left side of the heart, then 
the body.  In a baby the blood mostly goes through the right side of the 
heart, then through the foramen ovale to the left side of the heart, and 
then to the rest of the body,  but of the blood that goes through the 
pulmonary circulation, most of it never actually reaches the lungs, but 
instead goes through the ductus arteriosus then to the aorta, where it goes 
to the rest of the body.  So you see, the foramen ovale and the ductus 
arteriosus both help a baby's blood bypass the lungs. Shortly after birth 
the ductus arteriosus and the foramen ovale both close, since now the baby 
must have all its blood oxygenated in the lungs. 
Thank you for your question.
Sincerely,
Sarah Martin Mason, Mad Scientist