Describe the structure of the human heart with a labelled diagram.
How to lay out the answer. Follow the frame, then write it in your own words.
1 · Open in one line. The human heart is a hollow, muscular, four-chambered pump in the chest between the lungs, covered by the pericardium.
2 · Draw and label. [L.S. of the heart: right and left auricles, right and left ventricles, septum, tricuspid and bicuspid valves, chordae tendineae, semilunar valves, venae cavae, pulmonary artery, pulmonary veins, aorta]
3 · Chambers and vessels.
Right auricle: blood from the superior and inferior vena cava.
Left auricle: blood from four pulmonary veins.
Right ventricle: to the lungs by the pulmonary artery.
Left ventricle (thickest wall): to the body by the aorta.
4 · Valves. Tricuspid on the right, bicuspid (mitral) on the left, and semilunar valves at the pulmonary artery and aorta; all allow one-way flow.
5 · Working. The SA node starts each beat; one cardiac cycle takes about 0.8 s; lubb and dupp sounds; double circulation keeps the two kinds of blood apart.
6 · Real life. Exercise, less salt and no tobacco keep the heart muscle and its coronary arteries healthy.
7 · Close in one line. The heart pumps blood all our life, about 72 times a minute.
Scoring tip: Draw the right side of the heart on the left of your page, as if facing the person. Shade deoxygenated blood blue and oxygenated blood red.
