Within seconds of birth, babies get their oxygen for the first time. For that to happen, their small lungs and circulatory system must deform in just a few seconds. So how can a small human take the most difficult breath of his life in just a few seconds after birth?
First, how Circulatory system -In particular, lung And the heart — works in the womb.Does not provide lungs air For pregnant foets. Instead, while the baby gets oxygen from the placenta through the umbilical cord, they partially collapse and fill with fluid during development. Texas Heart Institute..
Most of the fetal blood supply bypasses the lungs through two fetal-specific blood vessels, because the lungs are not yet involved in the oxygen supply. The first foramen ovale allows oxygenated blood from the umbilical cord to flow directly from the right atrium of the heart to the left atrium, rather than going to the right ventricle and lungs as in adults. Philadelphia Children’s Hospital..The second ship called Ductus arteriosusIt connects the main arteries and the main pulmonary arteries, allowing the oxygenated blood of the foetation to move away from the lungs and towards the lower body. American Heart Association..
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Unlike adults heart“When a baby comes out, the right side of the heart is predominant,” said Dr. Jae Kim, a neonatologist and dean of the neonatal department at Cincinnati Children’s Hospital. This is because oxygenated blood is pumped throughout the body through these two temporary shunts. However, after birth, the circulatory system is reorganized. According to a 2002 report published in the journal, the left ventricle becomes dominant and plays a role in pumping blood throughout the body, while the right ventricle takes on the new task of pumping low-oxygen blood to the lungs. Archive of childhood illnesses..
This change occurs in a series of rapid changes shortly after birth. First, the cells that secrete water into the fetal lungs begin to absorb water when the baby is born, draining fluid and creating a place for incoming oxygen, Kim said. “The lungs quickly migrate and fill with air.” This first breath can be so strong and dramatic that in some cases the newborn baby’s lungs are punctured. increase.
This initial swelling of the lungs dramatically reduces the pressure and resistance of the lungs to blood flow. According to a 2010 review of the journal, low pressure causes blood to be pumped from the right ventricle and redirects towards the newborn’s lungs. Physiological review..
According to a 2010 review, the foramen ovale closes when lung pressure drops below systemic blood pressure, or pressure on blood vessels during contraction of the heart. If there is no passage between the right and left atrium, deoxygenated blood begins to flow from the right atrium to the lower right ventricle and then to the lungs.
Low pressure in the lung system, on the other hand, damages blood from the ductus arteriosus, the blood vessel that allows blood to bypass the lungs and head for the body. No longer needed, the tube begins to contract and closes within the first two days of life.
At this point, 100% of the baby’s blood supply goes to the lungs. For the first time, carbon dioxide-saturated blood is pumped into the alveolar capillaries (small blood vessels in the lungs). Alveoli (small air sacs in the lungs) replace carbon dioxide in the blood with oxygen ingested by the baby.
According to Kim, it takes about five minutes for a healthy baby to “turn pink” and find some sort of normal condition. But the transition happens in one breath. “It’s a very magical moment,” he said.
Originally published in Live Science.
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