<P> When the left ventricle contracts ( systole ) , pressure rises in the left ventricle . When the pressure in the left ventricle rises above the pressure in the aorta , the aortic valve opens , allowing blood to exit the left ventricle into the aorta . When ventricular systole ends , pressure in the left ventricle rapidly drops . When the pressure in the left ventricle decreases , the aortic pressure forces the aortic valve to close . The closure of the aortic valve contributes the A component of the second heart sound ( S ) . </P>
<P> When the left ventricle contracts ( systole ) , pressure rises in the left ventricle . When the pressure in the left ventricle rises above the pressure in the aorta , the aortic valve opens , allowing blood to exit the left ventricle into the aorta . When ventricular systole ends , pressure in the left ventricle rapidly drops . When the pressure in the left ventricle decreases , the aortic pressure forces the aortic valve to close . The closure of the aortic valve contributes the A component of the second heart sound ( S ) . </P>
what causes the closing of the aortic semilunar valve
what causes the closing of the aortic semilunar valve
When the pressure in the left ventricle decreases , the aortic pressure forces the aortic valve to close
When the pressure in the left ventricle decreases , the aortic pressure forces the aortic valve to close