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:
“The boredom of Sunday afternoon, which drove de Quincey to drink laudanum, also gave birth to surrealism: hours propitious for making bombs.”
—Cyril Connolly (1903–1974)
“Thirty-five is a very attractive age. London society is full of women of the highest birth who have, of their own free choice, remained thirty-five for years.”
—Oscar Wilde (1854–1900)