ANATOMY

Detailed explanation-1: -The heart valves open and close passively because of pressure differences on either side of the valve. When pressure is greater behind the valve, the leaflets are blown open and the blood flows through the valve. However, when pressure is greater in front of the valve, the leaflets snap shut and blood flow is stopped.

Detailed explanation-2: -The four heart valves open and close in response to pressure changes that occur in the ventricles during each cardiac cycle. When the ventricles relax, their pressures drop below those of the atria, pulmonary trunk artery, and aorta. AV valves to open as their cusps passively drop downward.

Detailed explanation-3: -How do the heart valves function? As the heart muscle contracts and relaxes, the valves open and close, letting blood flow into the ventricles and out to the body at alternate times.

Detailed explanation-4: -When the left ventricle contracts, the mitral valve closes and the aortic valve opens. This is so blood flows into the aorta and out to the rest of the body. While the left ventricle is relaxing, the right ventricle also relaxes. This causes the pulmonary valve to close and the tricuspid valve to open.

Detailed explanation-5: -At the end of diastole, the atria contract, squirting a small amount of extra blood into the ventricles. This increases the ventricles’ pressure so that it is now higher than that in the atria, causing the atrioventricular valves (mitral/tricuspid) to close.