What part of the ciculatory system returns blood to the heart from the lower body.

The part of the circulatory system that returns blood to the heart from the lower body is the Inferior Vena Cava. Here are the steps of how it works:

1. Deoxygenated blood from the lower part of the body, or blood that has circulated through the body and has had its oxygen used up, enters the Inferior Vena Cava.

2. The Inferior Vena Cava, which is the largest vein in the human body, carries this deoxygenated blood from the lower half of the body back towards the heart.

3. This blood enters the right atrium of the heart.

4. From the right atrium, the blood is pumped into the right ventricle.

5. The right ventricle pumps the blood to the lungs through the pulmonary artery where it gets oxygenated.

6. The oxygenated blood then returns to the heart, entering the left atrium.

7. From the left atrium, the blood is pumped into the left ventricle.

8. Finally, the left ventricle pumps the oxygenated blood out through the aorta to be circulated throughout the body.

So, in summary, the Inferior Vena Cava is the part of the circulatory system that returns deoxygenated blood from the lower body back to the heart.