Question

The diagram given below represents the human heart in one phase of its activity. Study the same and then answer the question that follow:

Which part of the heart is contracting in this phase? Give a reason to support your answer.

Answer 1

Ventricular muscles are contracting during this phase because the valves between the two ventricles and pulmonary artery and aorta are open while the atrio-ventricular valves are closed.