Final answer:
A neonate regulates cardiac output through mechanisms like the first breath and closing of ductus arteriosus, while SVR and LV function change after birth due to the opening and closing of shunts.
Step-by-step explanation:
Neonate Regulation of Cardiac Output
A neonate regulates cardiac output through several mechanisms. The first breath taken by a newborn inflates the lungs, decreases blood pressure, and causes the flow of blood to temporarily reverse direction through the foramen ovale, blocking the shunt. The closing of the ductus arteriosus ensures that all blood pumped to the pulmonary circuit will be oxygenated by the neonatal lungs. These changes help regulate cardiac output in neonates.
Changes in SVR and LV Function after Birth
After birth, systemic vascular resistance (SVR) decreases due to the opening of the umbilical vessels. Left ventricle (LV) function also changes as the heart adapts to the new circulatory patterns. The closing of the three shunts (foramen ovale, ductus arteriosus, and umbilical vessels) permanently redirects blood flow to the liver and lungs, facilitating normal LV function. These changes in SVR and LV function are essential for a newborn's postnatal adaptation.