The sinus venosus receives blood returning from what?

Click the area of the septum secundum.

The major development of the fetal heart is completed by the end of week _____.

The optimal time to perform a complete fetal echocardiogram is __________ weeks.

Blood pressure in the _____ becomes higher than that in the ______ in neonatal circulation. 

Once the baby is born, blood pressure will immediately ___________ in the newborn’s IVC and RA. 

Prior to week ____, the heart is a pair of tubes sitting on either side of the midline of the embryo. 

A piece of the ____________________ acts as a flap at the level of the foramen ovale and controls the blood flow between the two atria. 

  When a partial pressure gradient exists for a gas, it will move from the area of its LOWER partial pressure to the area of HIGHER partial pressure.  

  The key anatomic features of the respiratory membrane that make alveolar gas exchange so efficient are….