Question

During ventricular systole, which valves are open?

• A. AV valves
• B. Semilunar valves
• C. Both AV and semilunar valves
• D. All valves closed

Hint:

There is a very brief moment at the beginning of systole called "isovolumetric contraction" where all valves are closed, but the "open" state during systole refers to the ejection phase.

Answer 1

The Correct Option is B

Step 1: Understanding the Concept:
Ventricular systole is the phase of the cardiac cycle when the ventricles contract to pump blood out of the heart into the pulmonary and systemic circulation.

Step 2: Detailed Explanation:
The sequence during ventricular systole is as follows:
1. As the ventricles start contracting, pressure rises rapidly.
2. To prevent blood from flowing back into the atria, the Atrioventricular (AV) valves snap shut.
3. Once the pressure in the ventricles exceeds the pressure in the aorta and pulmonary artery, the Semilunar valves are forced open.
4. This allows the oxygenated blood to leave the left ventricle via the aorta and deoxygenated blood to leave the right ventricle via the pulmonary artery.

Step 3: Final Answer:
During the active ejection phase of ventricular systole, the semilunar valves are open.