Fetal circulation

Fetal circulation is called placental blood circulation and has its own characteristics. They are related to the fact that in utero the respiratory and digestive systems are not fully functioning and the fetus is forced to obtain all necessary for life and development of materials with the mother's blood, that is to eat a mixed arterial-venous blood.

The blood enters the mother to the so-called afterbirth - the placenta (placenta), which connects with the umbilical vein (v. umbilicalis). Umbilical Vienna is part of the umbilical cord (umbilical cord). Once in the body of the fetus, it gives two branches, one of which empties into the portal vein , the other - in the venous duct (ductus venosus), who in turn - in the inferior vena cava . The blood from the lower body of the embryo is mixed with arterial blood from the placenta and in the inferior vena cava enters the right atrium . Most of this blood through the foramen ovale atrial wall goes directly to the left atrium , without falling into the pulmonary circulation, and then sent to the left ventricle and aorta . A smaller part of the mixed blood through the right atrio-ventricular opening is in the right ventricle . The upper hollow Vienna is only venous blood by collecting it from the upper body of the embryo and giving the right atrium. Of right atrial blood enters the right ventricle, and then - in the pulmonary trunk. Pulmonary trunk is connected to the aorta arterial duct (ductus arteriosus), in which blood is sent to the aortic arch. Ductus arteriosus carries most of the blood because the pulmonary artery of the embryo are weak. The aorta receives mixed blood and gave their branches to spread it throughout the body of the fetus.

In Fig. 238.
Arteries and veins of the fetus
1 - aortic arch;
2 - the ductus arteriosus;
3 - upper hollow Vienna;
4 - left atrium;
5 - pulmonary trunk;
6 - the right atrium;
7 - the left ventricle;
8 - the right ventricle;
9 - abdominal aorta;
10 - venous flow;
11 - Vienna gate;
12 - umbilical Vienna;
13 - lower hollow Vienna;
14 - placenta;
15 - umbilical artery

From the abdominal aorta depart two umbilical arteries (aa. umbilicales), on which part of the blood from the body of the embryo enters the placenta, where it is cleansed of carbon dioxide and metabolic products. Pure arterial blood in the umbilical vein enters the body again of the fruit.

At birth, after the umbilical cord, the link with the body of the mother of the fetus is broken, and after the first breath of the lungs and blood vessels to straighten out, which leads to the top of the functioning of the pulmonary circulation. In the left half of the heart increases the pressure of the child, the umbilical vein and artery zapustevayut, the foramen ovale closes valve, resulting in a cease communication between the atria. Later, the foramen ovale, venous and arterial duct is completely overgrown, and the blood circulation is established, typical of an adult.





List of Abbreviations

a., aa. — arteria, arteriae (artery, the artery)

lig., ligg. — ligamentum, ligamenta (ligament, the ligaments)

m., mm. — musculus, musculi (muscle, the muscle)

n., nn. — nervus, nervi (nerve, the nerve)

r., rr. — ramus, rami (branch)

s. — seu (or)

v., vv. — vena, venae (vienna)