Fetal Circulation

 

Fetal circulation

3 fetal circulatory features that change at birth for the conversionfetalcirc to adult circulation

 1. Foramen ovale 

  • interatrial opening

  • allows blood to flow from the right to the left atrium of the heart

  • acts as a valve for blood to flow from the right atria to the left atria of the heart

  • this allows blood to circumnavigates the pulmonary circuit and the lungs which are nonfunctional inutero

 2. Ductus arteriosus 

  • between the pulmonary and aortic trunk

  • blood flows into the R atrium and R venticle, but also into L atrium via the foramen ovale

  • 25% of blood bypasses the pulonmary circuit in this manner

  • more than 90% of the blood leaving the right ventricle passes through the ductus arteriosus, entering the systemic circuit (rather than continuing to the lungs as it would in adult circulation)

3. Ductus venosus

  • collects blood from the umbilical vein (carries oxygenated blood) and veins of the liver to nourish fetal tissues

  • empties into inferior vena cava

 

Martini, Fredric, H. 2006. Fundamentals of anatomy and physiology. 7th ed. Pearson Education Inc. USA.

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