Foramen secundum

Foramen Secundum is an opening in the atrial septum of the heart during the fetal stage. It is one of the two foramina, the other being the foramen ovale, that allow blood to bypass the lungs in the fetal circulation system. The foramen secundum is formed by the degradation of the septum primum, a thin wall separating the two atria of the heart.

Development

The foramen secundum begins to form in the fourth week of embryonic development. It is created by the apoptosis, or programmed cell death, of cells in the septum primum. This process creates a hole in the septum primum, which becomes the foramen secundum.

Function

The foramen secundum, along with the foramen ovale, plays a crucial role in the fetal circulation. In the fetus, the lungs are not yet functional, and the foramen secundum allows blood to bypass the lungs and go directly to the body. This is essential for the survival of the fetus, as it allows oxygenated blood from the mother to reach the fetus's tissues.

Closure

After birth, the foramen secundum closes as part of the changes that occur in the circulatory system to allow the lungs to take over the role of oxygenating the blood. The closure of the foramen secundum is usually complete by the first year of life.

Clinical Significance

If the foramen secundum does not close properly after birth, it can lead to a condition known as atrial septal defect. This can cause problems such as heart failure, pulmonary hypertension, and other serious health issues.

See Also

• Heart
• Atrial septum
• Foramen ovale
• Fetal circulation
• Atrial septal defect

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