The diagram shows a view from the front of a section through the heart and associated blood
vessels. Which sequence of numbers shows the course of blood flow from the point of entry to the
heart from the lungs, to its eventual exit from the heart to supply the lungs?

Answer:

1) B

• 1 is the Aorta
• 2 is the pulmonary vein
• 3 is the left atrium
• 4 is the left ventricle
• 5 is the right ventricle
• 6 is the right atrium
• 7 is the vena cava
• 8 is the pulmonary artery

From the lungs, the blood will flow into the heart via the pulmonary vein (2)
From the pulmonary vein, the blood will enter the left atrium (3)
From the left atrium, the blood will enter the left ventricle (4)
From the left ventricle, the blood will flow to the rest of the body via the aorta (1)
From the body, the blood returns to the heart via the vena cava (7)
From the vena cava, the blood will enter the right atrium (6)
From the right atrium, the blood will enter the right ventricle (5)
From the right ventricle, the blood will flow to the lungs via the pulmonary artery (8)

So the order is:
2  3  4  1  7  6  5  8

The answer is B.