Why does the aortic valve close first?

The closing pressure (the diastolic arterial pressure) on the left is 80 mmHg as compared to only 10 mmHg on the right. This higher closing pressure leads to earlier closure of the aortic valve. In addition, the more muscular and stiff “less compliant” left ventricle (LV) empties earlier than the right ventricle.

Do the aortic and pulmonary valves close at the same time?

This closes the mitral and tricuspid valves preventing back blood flow. At the same time, the aortic and pulmonic valves open to let blood be pumped out of the heart. The left and right ventricles relax. The aortic and pulmonic valves close preventing backward blood flow into the heart.

What causes the pulmonary and aortic valves to close when the ventricles relax?

However, when the ventricles relax, arterial pressure exceeds ventricular pressure and the semilunar valves snap shut. This is due to the elevated pressures in the aorta and the pulmonary artery pushing the blood back toward the ventricles to close the semilunar valves.

Why does A2 close before P2?

Both A2 and P2 close when the pressure above the respective valves are greater than the pressure in the ventricles below. Given the lower vascular resistance of the pulmonary artery, during inspiration, the pulmonary artery is able to tolerate more volume of blood before the pressure above the valve increases.

Why is the second heart sound louder than the first?

The second heart sound (S2) (see Figure 1-9) is produced by passive closure of the aortic and pulmonic valves. It is short, high pitched, and sharp. It is loudest over the aortic and pulmonic areas. A split S2 (see Figure 1-9) is due to closure of the pulmonic valve after the aortic valve.

Why do heart valves open and close quizlet?

What causes heart valves to open or close? The opening and closing of the AV valves is dependent on pressure differences between the atria and ventricles. When atrial pressure exceeds ventricular pressure the AV valves are pushed open and blood flows into the ventricles.

What causes the cardiac valves to open and close quizlet?

Why is there a single S2 in transposition of great arteries?

Due to the anterior location of the aorta, the second heart sound (S2) is accentuated and is usually single.

Why is S2 fixed in ASD?

Because the atria are linked via the defect, inspiration produces no net pressure change between them, and has no effect on the splitting of S2. Thus, S2 is split to the same degree during inspiration as expiration, and is said to be “fixed.”