Snap & Solve (Biology)
Chap 19 Transport System
'lub'
Atrioventricular valve close and produce 'lub' sound as the blood pressure in ventricle is higher than atria.
'dup'
Semilunar valves close and produce 'dup' sound as the blood pressure in the aorta and pulmonary artery is also higher than blood pressure in ventricles.