Question

The diagram given below represents a section of the human heart. Answer the questions that follow :

(i) Which parts of heart are in the diastolic phase? Give a reason to support your answer.
(ii) Label the parts numbered 1 and 2 in the diagram. What type of blood flows through them?
(iii) What causes the heart sounds ‘LUBB’ and ‘DUP’?
(iv) Name the blood vessels that supply oxygenated blood to the heart muscles.
(v) Draw neat labelled diagrams of a cross section of an artery and a vein.

Answer 1

(i) Ventricles are in diastolic phase. The arrows indicate blood entering the ventricles. During a ventricular diastole, the valves between atria and ventricles open which allow the entry of blood into the ventricles.
(ii) 1 – Pulmonary artery, 2 – Pulmonary veins
(iii) Closing of the bicuspid and tricuspid valves causes the ‘LUBB’ sound, and the closing of semilunar valves causes the ‘DUP’ sound.
(iv) Coronary artery supplies oxygenated blood to the heart muscles.

(v) Cross-section of an artery and a vein: