FETAL CIRCULATION

FETAL HEART FORMATION

FETAL CIRCULATION

With birth, a change from paral le l fl ow through the heart to a ser ia l one gradual ly takes place. The fo l lowing changes must occur:

The gas exchange takes place in the baby's lungs. By cutt ing the umbi l ica l cord, the placental c i rculat ion system is switched off . The feta l heart shunts become c losed.

With the act ivat ion of breathing the lungs becomes distended, the capi l lary network di lated, the pressure in the r ight atr ium s inks in comparison with that of the left one. This pressure turnaround in the atr ia causes the foramen ovale to be pressed becomes funct ional ly c losed now referred to as the fossa oval is .

Towards the end of the fi rst year, it has also grown together in 99% of the babies --> The shunt between the left and right atrium is closed.

On the other hand, with the cutt ing of the umbi l ica l cord fo l lowing birth, the placental low res istance area a lso disappears and the per ipheral res istance increases in the systemic c i rculat ion. The pO2 pressure in the aorta increases s ince the blood is now oxygenated direct ly in the baby's lungs. This increase in pO2 tr iggers a contract ion of the smooth musculature in the wal l of the ductus arter iosus and thereby to a funct ional seal .

After a few weeks or months this shunt completely c losed the remnant is known as the l igamentum arter iosus.

The sever ing of the baby's umbi l ica l cord leads to the obl i terat ion of the umbi l ica l vessels , pr imari ly through act ive constr ict ion of their muscular layer. The umbi l ica l arter ies form the media l umbi l ica l l igaments whi le the umbi l ica l veins form the l igamentum teres.

AFTER BIRTH THINGS CHANGE