Table 3.11 - Rerouting of Circuits at Birth.
| Structure(s) | Event | Time | Cause |
|---|---|---|---|
| Umbilical Art's | closure | 2 - 4 min. | smooth muscle contraction (PO2 & cold); ligature |
| Umbilical Vein | closure | 2 - 4 min. | same |
| Ductus Venosus | closure | hrs. - day | passive mechanical; smooth muscle contraction? |
| Foramen Ovale | closure | minutes | pressure in LA exceeds that in RA |
| Pulm. Vasculature | opening | minutes | smooth muscle relaxation (increased PO2); smooth muscle atrophy |
| Ductus Arteriosus | closure | hrs. - day | smooth muscle contraction with increased PO2 |