Question

Where does the blood in the upper body enters the heart?

Answer 1

Through the superior vena cava into the right atrium.

Explanation:

Blood from the upper body flows through different veins all of which combine into the superior vena cava, which is one of the two big veins entering the heart with de-oxygenated blood. The other vein is the inferior vena cava which carries blood from the lower body.

The superior vena cava enters the heart at the right atrium.

Oxygenated blood from the lungs enters the heart through the four pulmonary veins (two from each lung). This blood is received in the left atrium.