Closing During Birth
To provide proper blood flow as a a newborn, the foramen secundum and foramen ovale must close when birth occurs. Since the lungs now require a significant amount of blood flow, the vessels going to and from the lungs undergo dilation. While the pulmonary artery and pulmonary veins are dilating, the umbilical artery and umbilical vein are severed due to the cutting of the umbilical cord, or the funiculus umbilicalis. This combination results in a reversal of pressure differences between the atria and the septum primum is permanently forced against the septum secundum. This holds true even during atrial diastole, when the pressure is significantly less than atrial systole.
Read more about this topic: Foramen Secundum
Famous quotes containing the words closing and/or birth:
“From Harmony, from heavenly Harmony
This universal Frame began:
From Harmony to Harmony
Through all the Compass of the Notes it ran,
The Diapason closing full in Man.”
—John Dryden (1631–1700)
“The passions do very often give birth to others of a nature most contrary to their own. Thus avarice sometimes brings forth prodigality, and prodigality avarice; a man’s resolution is very often the effect of levity, and his boldness that of cowardice and fear.”
—François, Duc De La Rochefoucauld (1613–1680)