AP BIOLOGY

Detailed explanation-1: -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-2: -When the left ventricle contracts, the mitral valve closes and the aortic valve opens, so blood flows into the aorta.

Detailed explanation-3: -The atrioventricular valves remain open while the semilunar valves are closed. During the middle part of a diastole a small volume of blood flows into the ventricles. This is the blood flowing from veins and passing the atria to fill the ventricles.

Detailed explanation-4: -The isovolumetric contraction causes left ventricular pressure to rise above atrial pressure, which closes the mitral valve and produces the first heart sound. The aortic valve opens at the end of isovolumetric contraction when left ventricular pressure exceeds aortic pressure. aortic and pulmonary valves closed.