Question

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

(i) Name the phase.
(ii) Which part of the heart is contracting in this phase? Give a reason to support your answer.
(iii) Name the parts labelled 1 to 4.
(iv) What type of blood flows through ‘2’?
(v) State the function of the part numbered ‘5’.
(vi) Name the membrane that covers the heart.

Answer 1

(i) Ventricular systole

(ii) Ventricles are contracting in this phase. In the diagram given, tricuspid valves and bicuspid valves are closed, while the semi-lunar valves are open.

(iii)

1 – Pulmonary artery
2 – Aorta
3 – Bicuspid valve
4 – Semilunar valve (aortic semilunar valve)

(iv) Oxygenated blood flows through ‘2’, i.e. aorta.

(v) ‘5’ is pulmonary semilunar valve. It prevents the backflow of blood into the right ventricle at the time of ventricular diastole.

(vi) Pericardium covers the heart.