Question

Given below is a highly schematic diagram of the human blood circulatory system.
Which part (state the number) represents the heart? Give reason in support of your answer.

Answer 1

Part 3 represents the heart. Blood flows twice in the heart before it completes one full round the short pulmonary circulation (part 2) and the long systemic circulation emerges from part 3. For this reason, the blood circulation in the human body is called double circulation and happens through part 3.