What happens during the ejection phase of the cardiac cycle?

What happens during the ejection phase of the cardiac cycle?

• A. AV valves open and blood flows into ventricles.
• B. Blood is ejected from the ventricles; ventricular and aortic pressure increase.
• C. Ventricles fill again.
• D. Atrial pressure increases.

Answer: (B)

The ejection phase is when the ventricles actively contract to push blood out into the arteries. As contraction raises ventricular pressure above the pressures in the aorta and pulmonary artery, the semilunar valves open and blood is ejected into the aorta and pulmonary trunk. This outflow increases the pressures in both the ventricles (during contraction) and the arterial system (the aorta, at least during systole). After ejection, the ventricle begins to relax and the semilunar valves close, marking the transition toward relaxation.

The ejection phase is when the ventricles actively contract to push blood out into the arteries. As contraction raises ventricular pressure above the pressures in the aorta and pulmonary artery, the semilunar valves open and blood is ejected into the aorta and pulmonary trunk. This outflow increases the pressures in both the ventricles (during contraction) and the arterial system (the aorta, at least during systole). After ejection, the ventricle begins to relax and the semilunar valves close, marking the transition toward relaxation.