When a newborn takes its first breath, what physical changes occur in the heart to increase oxygenation of the body?
The ductus arteriosus expands to allow more blood to enter the lungs
The foramen ovale closes, preventing blood exchange from right to left in the heart
The umbilical vein that carried oxygenated blood in utero becomes the ascending aorta entering the right atrium
The ductus venosus shunts oxygenated aortic blood to the lungs.
The Correct Answer is B
The foramen ovale closes, preventing blood exchange from right to left in the heart. This is because the foramen ovale is a fetal shunt that allows blood to bypass the lungs and flow from the right atrium to the left atrium. After birth, when the baby starts to breathe air, the lungs expand and the pulmonary resistance decreases. This causes an increase in blood flow and pressure in the left atrium, which pushes the foramen ovale closed. This prevents blood from mixing between the right and left sides of the heart and allows oxygenated blood to circulate to the body¹².
Choice A is not correct because the ductus arteriosus does not expand to allow more blood to enter the lungs. The ductus arteriosus is another fetal shunt that
connects the pulmonary artery to the aorta. It allows blood to bypass the lungs and flow from the right ventricle to the aorta. After birth, when the baby starts to breathe air, the oxygen concentration in the blood increases and causes the ductus arteriosus to constrict and close. This increases blood flow to the lungs and decreases blood flow to the aorta.
Choice C is not correct because the umbilical vein that carried oxygenated blood in utero does not become the ascending aorta entering the right atrium. The umbilical vein is a fetal vessel that carries oxygenated blood from the placenta to the fetus. It connects to either the portal vein or the ductus venosus, which then drains into the inferior vena cava. After birth, when the umbilical cord is clamped and cut, the umbilical vein collapses and becomes a fibrous cord called ligamentum teres hepatis.
Choice D is not correct because the ductus venosus does not shunt oxygenated aortic blood to the lungs. The ductus venosus is another fetal vessel that connects the umbilical vein to the inferior vena cava. It allows some of the oxygenated blood from the placenta to bypass the liver and enter directly into the systemic circulation. After birth, when the umbilical cord is clamped and cut, the ductus venosus closes and becomes a fibrous cord called ligamentum venosum.
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is D
Explanation
Massage the client’s fundus. This is because the most common cause of postpartum hemorrhage is uterine atony, which is the failure of the uterus to contract after delivery. Massaging the fundus can stimulate uterine contractions and reduce bleeding by compressing the blood vessels at the placental site.
Choice A is not correct because administering oxytocin is not the first action to take. Oxytocin is a medication that can also help the uterus contract, but it should be given after assessing the uterine tone and bleeding.
Choice B is not correct because observing for pooling of blood under the buttocks is not a priority action. It can help estimate the amount of blood loss, but it does not address the cause of bleeding or stop it.
Choice C is not correct because checking the client’s blood pressure is not the first action to take. Blood pressure can indicate hypovolemia due to blood loss, but it is not a sensitive indicator and may remain normal until a significant amount of blood is lost.
Correct Answer is A
Explanation
Clear the respiratory tract. This is because clearing the respiratory tract is the first step in the initial care of a newborn following vaginal delivery. The respiratory tract includes the nose, mouth, and lungs.
Clearing the respiratory tract helps the baby breathe more easily and prevents aspiration of amniotic fluid, blood, or mucus. The nurse can use a bulb syringe or a suction device to gently remove any fluid from the baby's nose and mouth.
Choice B is not correct because drying the infant off and covering the head is not the first action to take. Drying and covering the infant helps prevent heat loss and hypothermia, which are important for newborn care. However, this should be done after clearing the respiratory tract.
Choice C is not correct because stimulating the infant to cry is not the first action to take. Stimulating the infant to cry can help expand the lungs and improve oxygenation, which is also important for newborn care. However, this should be done after clearing the respiratory tract.
Choice D is not correct because clamping the umbilical cord is not the first action to take. Clamping and cutting the umbilical cord separates the baby from the placenta, which is no longer needed after birth. However, this should be done after clearing the respiratory tract.
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