At Birth
At birth, when the infant breathes for the first time, there is a decrease in the resistance in the pulmonary vasculature, which causes the pressure in the left atrium to increase relative to the pressure in the right atrium. This leads to the closure of the foramen ovale, which is then referred to as the fossa ovalis. Additionally, the increase in the concentration of oxygen in the blood leads to a decrease in prostaglandins, causing closure of the ductus arteriosus. These closures prevent blood from bypassing pulmonary circulation, and therefore allow the neonate's blood to become oxygenated in the newly operational lungs.
Read more about this topic: Fetal Circulation
Famous quotes containing the word birth:
“Some say that ever ‘gainst that season comes
Wherein our Saviour’s birth is celebrated,
This bird of dawning singeth all night long,
And then they say no spirit dare stir abroad,
The nights are wholesome, then no planets strike,
No fairy takes, nor witch hath power to charm,
So hallowed, and so gracious, is that time.”
—William Shakespeare (1564–1616)
“Not yet the thirtieth year, the thirtieth
Station where time reverses his light heels
To run both ways, and makes of forward back;
Whose long co-ordinates are birth and death....”
—Allen Tate (1899–1979)