The diagram below represents the human heart in one phase of its functions. 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.
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(i) Ventricular Systole.
(ii) Ventricle is contracting because both tricuspid and bicuspid valves are closed whereas both pulmonary semi-lunar and Aortic semi-lunar valves are open to pump the blood out of the two ventricles.
(iii) The parts labelled 1 to 4 are:
- 1 → Pulmonary Artery
- 2 → Aorta
- 3 → Bicuspid/Mitral valve
- 4 → Aortic Semilunar valve
(iv) Oxygenated blood
(v) Part numbered '5' are the Pulmonary Semilunar valves. They allow the deoxygenated blood to flow from the right ventricle to the lungs and prevents its backflow.
(vi) Pericardium