Answer to Question 1
ANS: B
The ductus arteriosus shunts blood from the pulmonary artery to the aorta, bypassing the lungs during fetal life. The functional closure of the ductus arteriosus usually occurs approximately 15 to 20 hours after birth, with fibrosis of the ductus occurring approximately 3 to 4 weeks after birth. The structure allowing blood to flow from right atrium to left atrium is the foramen ovale. The abnormality of the aorta arising from the right ventricle and the pulmonary artery originating from the left ventricle is known as transposition of the great vessels. Coarctation of the aorta is a narrowing of the aorta.
Answer to Question 2
ANS: A
To live independently from the mother, pulmonary ventilation must be quickly established through lung expansion. The first breath of a healthy newborn occurs within seconds after birth, and by 30 seconds of life the neonate usually is breathing well on his or her own.