Question

Normally in an adult heart, the interatrial septum bears an oval-shaped depression known as the ___________, a remnant of an opening in the fetal heart known as the foramen ovale. The foramen ovale allowed blood in the fetal heart to pass directly from the right atrium to the left atrium, allowing some blood to bypass the pulmonary circuit. Within seconds after birth, a flap of tissue known as the septum primum that previously acted as a valve closes the foramen ovale and establishes the typical cardiac circulation pattern.

Answer 1

The fossa ovalis is the depression on the interatrial septum marking the location of the closed foramen ovale, which during fetal development allowed blood to bypass the lungs.

Step-by-step explanation:

Normally in an adult heart, the interatrial septum bears an oval-shaped depression known as the fossa ovalis, a remnant of an opening in the fetal heart known as the foramen ovale. The foramen ovale allowed blood in the fetal heart to bypass the pulmonary circuit by flowing directly from the right atrium to the left atrium.

After birth, a flap of tissue called the septum primum closes the foramen ovale, thus establishing a typical cardiac circulation pattern which effectively separates oxygen-rich blood from oxygen-poor blood within the heart.

Occasionally, when the septum primum does not close properly at birth, the condition is called patent foramen ovale (PFO). While a PFO can be asymptomatic, it may in some cases require medical intervention to prevent complications.