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.

Answer and Explanation

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.

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Correct Answer is C

Explanation

Tachycardia. Tachycardia is a sign of hypovolemic shock from postpartum hemorrhage, which occurs when the blood volume is reduced and the heart rate increases to compensate for the low cardiac output and tissue perfusion. Tachycardia is usually the first sign of hypovolemic shock, as it can occur even before a significant drop in blood pressure or other symptoms.

Choice A. Hypotension is incorrect because it is a late sign of hypovolemic shock, which occurs when the compensatory mechanisms fail to maintain adequate blood pressure and organ perfusion.

Choice B. Cold, clammy skin is incorrect because it is a sign of peripheral vasoconstriction, which occurs as a compensatory mechanism to divert blood flow to the vital organs. However, it is not specific to hypovolemic shock and can occur in other types of shock as well.

Choice D. Decreased urinary output is incorrect because it is a sign of renal impairment, which occurs as a result of reduced blood flow to the kidneys. However, it is not specific to hypovolemic shock and can occur in other types of shock or renal disorders as well.

A. The Moro reflex was elicited. B. This is abnormal for a full-term infant. C. There may be an abnormality in the musculoskeletal system. D. The full-term infant should not react to sudden movement.

Correct Answer is A

Explanation

The Moro reflex was elicited. This is because the Moro reflex is a normal newborn reflex that occurs when the baby is startled by a loud noise or a sudden movement. The baby responds by extending the arms and legs, opening the hands, and then bringing the arms and legs back to the chest.

The Moro reflex is present at birth and disappears by 3 to 6 months of age.

Choice B is wrong because this is not abnormal for a full-term infant. The Moro reflex is a sign of a healthy nervous system and brain development.

Choice C is wrong because there is no evidence of an abnormality in the musculoskeletal system. The Moro reflex does not indicate any problems with the bones or muscles of the baby.

Choice D is wrong because the full-term infant should react to sudden movement. The Moro reflex is a protective response that helps the baby cling to the mother in case of danger.

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When a newborn takes its first breath, what physical changes occur in the heart to increase oxygenation of the body?

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Naxlex Comprehensive Predictor Exams

The first sign of hypovolemic shock from postpartum hemorrhage is likely to be:

Correct Answer is C

Explanation

When the newborn's crib was moved suddenly, the nurse noticed that his legs flexed and the arms fanned out, and then both came back toward the midline. The nurse would interpret this behavior as:

Correct Answer is A

Explanation

The nurse is visiting a new mother who has been home with a new infant for 4 days. Which observation indicates that the mother's home environment was inadequately assessed prior to being discharged from the hospital?

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A nurse is reviewing the medical record of a client who experienced a vaginal birth 2 hr ago. The nurse should identify which of the following findings places the client at risk for a postpartum hemorrhage.

A nurse is caring for several newborn clients. For which of the following findings should the nurse notify the charge nurse?