Question

The diagram given below represents the human heart in one phase of its functions. Study the diagram carefully and answer the questions that follow:

1. Name the phase.
2. Which part of the heart is contracting in this phase? Give a reason to support your answer.
3. Name the parts labelled 1 to 4.
4. What type of blood flows through 2?
5. State the function of the part numbered ‘5’.
6. Name the membrane that covers the heart.

Answer 1

1. Ventricular systole
2. Ventricles are contracting in this phase. In the diagram given, the tricuspid valve and bicuspid valve are closed, while the semilunar valves are open.
3. 1. Pulmonary artery
   2. Aorta
   3. Bicuspid valve
   4. Semilunar valve (aortic semilunar valve)
4.  Oxygenated blood flows through ‘2’, i.e., the aorta.
5. Part ‘5’ is the pulmonary semilunar valve. It prevents the backflow of blood into the right ventricle at the time of ventricular diastole.
6. Pericardium