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:
“TV gives everyone an image, but radio gives birth to a million images in a million brains.”
—Peggy Noonan (b. 1950)
“But whoever gives birth to useless children, what would you say of him except that he has bred sorrows for himself, and furnishes laughter for his enemies.”
—Sophocles (497–406/5 B.C.)