Fetal
- Pulmonary trunk structure similar to Aorta
- Wall thickness and Elastic configuration similar
- Lung has no function regards to blood oxygenation
- Oxygenated blood reaches from Placenta
- Placental blood flows thru atrium, thru foramen ovale to systemic circulation
- Blood from superior venacava and some blood from Pleurth, flow thru RV and
Pulmonary Trunk thru ductus arteriosus to systemic circulation
- Only 10 - 15% of RV stroke volume reaches lungs
- Muscular Pulmonary arteries and airerioles have thick walls and narrow lumen
Postbirth & Adult
- Hemodynamic situation changes instantly
- Resistance in Pulmonary circulation decreases
- Ductus arteriosus functionally closed
- Increased Pulmonary Venous return with a Concomitant rise in left pressure causes
closure of foramen ovale
- Muscular Pulmonary artery becomes wider
- Medical Thickness decreases and lumen widens
- Intima becomes flatter