Draw a sectional view of the human heart and label it. Describe double circulation.
How to lay out the answer. Follow the frame, then write it in your own words.
1 · Define in one line. In double circulation, blood passes through the heart twice in each cycle: once to the lungs and once to the body.
2 · Lung circuit. Oxygen-poor blood from the body enters the right atrium through the vena cava → right ventricle → pulmonary artery → lungs.
3 · Body circuit. Pulmonary veins bring oxygen-rich blood to the left atrium → left ventricle → aorta → body.
4 · Why it matters. The septum keeps the two kinds of blood apart, so oxygen supply is efficient, as warm-blooded birds and mammals need.
5 · Draw the heart. [Diagram: right and left atria, right and left ventricles, septum, valves, aorta, pulmonary artery, pulmonary veins, vena cava, arrows]
6 · Link to daily life. Regular exercise and less salt keep the heart and blood pressure healthy.
7 · Close in one line. Thus the four-chambered heart works as two pumps side by side.
Scoring tip: Show the direction of blood with arrows. Drawing the left ventricle wall thickest is an easy mark.
