1.
Fetal blood circulation
Presented By :-
Suhail Khan
B.sc (N) 3rd
Year
Ch. Kehar singh institute of
paramedical science and hospital
Baraut (Baghpat)

2.
Objective
At the end of the class the group will be able to;
1. Explain fetal circulation
2. Explain the difference between normal circulation and fetal
circulation
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3.
Introduction
• In animals that give live birth, the fetal circulation is the circulatory
system of a fetus. The term usually encompasses the
entire fetoplacental circulation, which includes the umbilical cord and
the blood vessels within the placenta that carry fetal blood.
• The fetal (prenatal) circulation differs from normal postnatal
circulation, mainly because the lungs are not in use. Instead,
the fetus obtains oxygen and nutrients from the mother through
the placenta and the umbilical cord
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4.
Gas exchange in Normal adult Gas exchange in fetus
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5.
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6.
Structures of fetoplacental circulation
1. Placenta : where gas exchange takes place during fetal life
2. Umbilical arteries: carry deoxygenated blood from the fetus to placenta
3. Umbilical vein: brings oxygenated blood coming from the placenta to the
fetus
4. Foramen ovale: connects the left and right atrium. It pushes blood from the
right atrium to the left atrium
5. Ductus venosus: carry oxygenated blood from umbilical vein to inferior
vena cava, bypassing fetal liver
6. Ductus arteriousus: carry oxygenated blood from pulmonary artery to
aorta, bypassing fetal lungs
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7.
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8.
Mechanism
Blood from the placenta is carried to the fetus by the umbilical vein.
This blood enters the fetal ductus venosus and is carried to the inferior
vena cava, while the rest enters the liver proper from the inferior
border of the liver.
The branch of the umbilical vein that supplies the right lobe of
the liver first joins with the portal vein.
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9.
The blood then moves to the right atrium of the heart.
 In the fetus, there is an opening between the right and left atrium
(the foramen ovale), and most of the blood flows through this hole
directly into the left atrium from the right atrium, thus
bypassing pulmonary circulation.
The continuation of this blood flow is into the left ventricle, and from
there it is pumped through the aorta into the body.
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10.
Some of the blood moves from the aorta through the internal iliac
arteries to the umbilical arteries, and re-enters the placenta,
where carbon dioxide and other waste products from the fetus are
taken up and enter the maternal circulation.
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11.
Some of the blood entering the right atrium does not pass directly to
the left atrium through the foramen ovale, but enters the right ventricle
and is pumped into the pulmonary artery.
 In the fetus, there is a special connection between the pulmonary
artery and the aorta, called the ductus arteriosus, which directs most of
this blood away from the lungs
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12.
Mechanism ( after birth )
At birth, when the infant breathes for the first time, there is a decrease
in the resistance in the pulmonary vasculature, which causes the
pressure in the left atrium to increase relative to the pressure in the
right atrium.
This leads to the closure of the foramen ovale, which is then referred
to as the fossa ovalis.
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13.
Additionally, the increase in the concentration of oxygen in the blood
leads to a decrease in prostaglandins, causing closure of the ductus
arteriosus.
These closures prevent blood from bypassing pulmonary circulation,
and therefore allow the neonate's blood to become oxygenated in the
newly operational lungs
ductus venosus = ligamentum venosum
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14.
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15.
• From the aorta, the oxygen-rich blood is sent to the brain and to the
heart muscle itself. Blood is also sent to the lower body.
• Blood returning to the heart from the fetal body contains carbon
dioxide and waste products as it enters the right atrium.
• It flows down into the right ventricle, where it normally would be sent
to the lungs to be oxygenated.
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Mechanism of deoxygenated blood

16.
• Instead, it bypasses the lungs and flows through the ductus arteriosus
into the descending aorta, which connects to the umbilical arteries.
From there, blood flows back into the placenta.
• There the carbon dioxide and waste products are released into the
mother's circulatory system. Oxygen and nutrients from the mother's
blood are transferred across the placenta. Then the cycle starts again.
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17.
• At birth, major changes take place. The umbilical cord is clamped and
the baby no longer receives oxygen and nutrients from the mother.
• With the first breaths of air, the lungs start to expand, and the ductus
arteriosus and the foramen ovale both close.
• The baby's circulation and blood flow through the heart now function
like an adult's.
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18.
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