What occurs during ventricular ejection?

What occurs during ventricular ejection?

• A. Ventricles are in systole, ejecting blood into the arterial trunks.
• B. Ventricles are in diastole, filling with blood.
• C. Atria contract, pushing blood into ventricles.
• D. AV valves close and no blood flows.

Answer: (A)

During ventricular ejection, the ventricles are contracting (systole) and actively pumping blood into the arteries. As the pressure inside the ventricles rises above the pressure in the aorta and pulmonary trunk, the semilunar valves open, and blood is ejected into the systemic and pulmonary circulations. The atrioventricular (AV) valves are closed during this time to prevent backflow into the atria, but that doesn’t stop flow; it simply gates it through the semilunar valves. This phase ends when ventricular pressure falls and the semilunar valves close, signaling the start of relaxation. The diastole phase involves filling, and atrial contraction helps fill the ventricles but is not the ejection itself. The notion that no blood flows because the AV valves are closed corresponds more to a brief isovolumetric contraction, not the ejection period.

During ventricular ejection, the ventricles are contracting (systole) and actively pumping blood into the arteries. As the pressure inside the ventricles rises above the pressure in the aorta and pulmonary trunk, the semilunar valves open, and blood is ejected into the systemic and pulmonary circulations. The atrioventricular (AV) valves are closed during this time to prevent backflow into the atria, but that doesn’t stop flow; it simply gates it through the semilunar valves. This phase ends when ventricular pressure falls and the semilunar valves close, signaling the start of relaxation. The diastole phase involves filling, and atrial contraction helps fill the ventricles but is not the ejection itself. The notion that no blood flows because the AV valves are closed corresponds more to a brief isovolumetric contraction, not the ejection period.