Final answer:
The structural and blood flow differences of the heart before and after birth are necessary for the transition from obtaining oxygen from the mother's blood to independent lung oxygenation. The closure of the foramen ovale and the ductus arteriosus after birth ensures oxygen-rich blood is properly distributed to the body and lungs.
Step-by-step explanation:
Before birth, the structural and blood flow differences of the heart are necessary due to the fact that the fetus does not use its lungs for oxygenation. Instead, oxygen and nutrients are obtained from the mother's blood through the placenta and umbilical cord. The heart has two shunts known as the foramen ovale and the ductus arteriosus, which allow blood to bypass the lungs and liver, respectively. These shunts close after birth as the lungs become functional and the newborn starts breathing on its own.
After birth, the changes in the fetal heart occur in response to the new oxygenation process through the lungs. The foramen ovale, which is an opening between the two atria, closes to separate the oxygen-rich blood from the systemic circulation from the oxygen-poor blood from the pulmonary circulation. Additionally, the ductus arteriosus, a blood vessel that connects the pulmonary artery to the aorta, constricts and eventually closes off, allowing blood to flow directly to the lungs.
Overall, these changes in the fetal heart are necessary to transition from the oxygenation of blood through the placenta to the independent oxygenation provided by the lungs after birth. This allows for proper oxygenation of tissues and removal of waste products, enabling the newborn to adapt to the extrauterine environment.