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General anatomy

Foetal circulation

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Surface

Locomotor system

Cardiovascular system

Nervous system

Fig. 41

Schema of foetal circulation.

The different colours indicate the oxygen content in the blood:

red = rich in oxygen,

blue = poor in oxygen,

purple = mixed blood.

Arrows indicate the direction of the blood flow.

*

S ho rt-circu it between the righ t and the left atrium

** S ho rt-circu it between the putm onary tru n k and the arch of aorta

* * * S ho rt-circu it between the um bilicat vein and the inferio r vena cava

Conversion from foetal to postnatal circulation:

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The valve-like connection between the right and the left atrium via

the foram en ovale is passively closed at the onset of respiratory

activity in the lungs

** The ductus arteriosus IBOTALLO], on the other hand, closes only

during the firs t m onths of life as its lum en gradually obliterates by

epithelial proliferation and increased tension of the wait.

***T h e ductus venosus (ARANTIUS) obliterates a fte r birth and becomes

the tigam entum venosum in the portal area of the liver.