Fetal Circulation

[DRHOYA]

Hey guys I always get these mixed up. Off the top of my head, I am thinking that the Foramen Ovale is a "hole" in the heart to shunt blood from the right to left atria? The Ductus Venosus, bypasses the fetal liver.....but why? And lastly, the Ductus Arteriosis bypasses fetal lungs. Feel free to correct me.

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[harrygt]

Hey guys I always get these mixed up. Off the top of my head, I am thinking that the Foramen Ovale is a "hole" in the heart to shunt blood from the right to left atria? The Ductus Venosus, bypasses the fetal liver.....but why? And lastly, the Ductus Arteriosis bypasses fetal lungs. Feel free to correct me.

You are right about all of them. Foramen Ovale prevents the blood from getting into the lungs from the right ventricle. WHy? because the lungs are not active in fetus, and there is not enough oxygen in the uterus for respiration by lungs. This foramen is in the wall between the atria.
But some of the blood from right atrium does not get in left atrium from foramen ovale. this portion gets into right ventricle and finally pumped to pulmonary arteries. There is another solution which is ductus arteriosus as you mentioned. This portion of the blood which escaped the foramen ovale gets back into aorta from the pulmonary artery directly by ductus arteriosus [connecting these too]
Liver needs to be bypassed as you said. Why? because liver's function is to clean the blood from toxics. However; the blood coming to the fetus is the mother's blood which is already clean blood. NO use in passing the liver.
I hope this helps.

 

[DRHOYA]

You are right about all of them. Foramen Ovale prevents the blood from getting into the lungs from the right ventricle. WHy? because the lungs are not active in fetus, and there is not enough oxygen in the uterus for respiration by lungs. This foramen is in the wall between the atria.
But some of the blood from right atrium does not get in left atrium from foramen ovale. this portion gets into right ventricle and finally pumped to pulmonary arteries. There is another solution which is ductus arteriosus as you mentioned. This portion of the blood which escaped the foramen ovale gets back into aorta from the pulmonary artery directly by ductus arteriosus [connecting these too]
Liver needs to be bypassed as you said. Why? because liver's function is to clean the blood from toxics. However; the blood coming to the fetus is the mother's blood which is already clean blood. NO use in passing the liver.


I hope this helps.

Thanks! Yeah, that makes sense about bypassing the liver due to the mother and her liver. And thanks for pointing out the Ductus Arteriosis being there to stop the little blood that does get into the right ventricle. It is also kind of scary to think what would happen if these 3 pathways failed/had problems closing up as the fetus developed!!

 

[harrygt]

Thanks! Yeah, that makes sense about bypassing the liver due to the mother and her liver. And thanks for pointing out the Ductus Arteriosis being there to stop the little blood that does get into the right ventricle. It is also kind of scary to think what would happen if these 3 pathways failed/had problems closing up as the fetus developed!!

I wish we would get real Bio questions like this instead of testing us on the metabolism in the Nuts of sea urchins [DO they have nuts?]